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BELTSVILLE BRANCH

CON/FER

NURSERY PRACTICE

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PRAIRIE PLAINS

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U.S. DEPARTMENT OF AGRICULTURE/FOREST SERVICE/AGRICULTURE HANDBOOK NO. 279
CONIFER NURSERY PRACTICE

in the

PRAIRIE-PLAINS

By J. H. Stoeckeler, principal soil scientist, Lake States

Forest Experiment Station (maintained by the U.S.

Department of Agriculture in cooperation with the

University of Minnesota), and P. E. Slabaugh, principal silviculturist, Lake States Forest Experiment Station (stationed at Bottineau, N. Dak.).

AGRICULTURE HAJVDROOK 279

Issued June 1965

U.S. DEPARTMEIVT OF AGRICULTURE, FOREST SERVICE

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C., 20402 - Price 50 cents
ACKNOWLEDGMENT

Forest nursery practices for the Prairie-Plains have developed through

research and the resourcefulness of nurserymen engaged in the production

of planting stock. The 50 years of experience gained in conifer propagation at the Bessey Nursery in the Nebraska National Forest has provided

the greatest single contribution to this handbook^ and special gratitude is

due M. K. Meines, the present superintendent. Other Federal nurseries

supplying material were operated by the Soil Conservation Service, by the

Prairie States Forestry Project (discontinued in 1942), and by the then

Bureau of Plant Industry (now the Agricultural Research Service). Much

assistance was received from State and commercial nurserymen, including

Albert Engstrom, Norman, Okla. ; John Molberg, Bottineau, N. Dak. ] Lloyd

Moffett and J. R. Weir, Fremont, Nebr.; and Clarence Jensen, Esmond,

N. Dak.
CONTENTS

Page

Introduction 1

Native conifers 1

History of conifer planting 4

Future of conifer planting 5

Collection and handling of seed 6

Importance of seed source 6

Seed collection zones and localities 7

Selection of individual stands and trees 8

Determination of seed ripeness and quality 8

Seed crop frequency 9

Seed yields 9

Methods of seed collection 11

Care of fresh seed 13

Seed extraction and cleaning 13

Seed storage 15

Seed testing 15

Seed dormancy and pretreatment 17

Selection of the nursery site 18

Sou 18

Water supply 19

Availability of markets, utilities, and labor 19

Shape, topography, and size of tract 20

Crop history of land 20

Development of the nursery site 21

Subdividing the nursery 21

Developing the irrigation system 21

Seedbed preparation and sowing 24

Staking out and preparing the beds 24

Computing the amount of seed to sow 25

Time of seeding 26

Broadcast versus drill sowing 27

Seeding equipment 27

Covering the seed 28

Seedbed care during germination and the seedling stage . 31

Half-shade 31

Soil moisture and irrigation 32

Weed control 34

Mechanical and hand weeding 34

Chemical control of weeds 34

Mineral spirits 34

Methyl bromide 35

Allyl alcohol 35

Miscellaneous chemicals 35

Possible harmful effects of chemicals on trees and soil. . 36

Page

Transplanting 36

Hand transplanting 36

Mechanical transplanting 37

Transplant spacing 38

Transplant losses 38

Season of transplanting 40

Top and root pruning 40

Hardening-off 41

Digging, grading, packing, storing, and shipping 42

Digging nursery stock 42

Grading 43

Packing 44

Storing and shipping 46

Potting and balling nursery stock 48

Age classes of stock needed for the Plains 50

Inventory 55

Soil management 57

Fertility requirements and the determination of

nutrient needs 57

Visual symptoms of malnutrition 57

Fertilizer applications and their results 59

Liquid fertiUzers as topdressings 60

Manure, compost, leaf mold, and peat 61

Cover and soil improvement crops 62

Maintenance of proper pH 62

Comparison of acidification with different chemicals.. 63

Carryover effect of acidification 66

The role of mycorrhizal fungi 67

Nursery protection ^0

Meteorological factors ^0

Wind '70

Heat ^^

Frost and winter damage 73

Nursery insects and mites 74

White grubs ^^

Nantucket pine tip moth 75

Red spiders ^^

Wireworms '6

Cutworms '^

Grasshoppers '6

Nursery diseases ''

Damping-off 77

Cedar blight "^^

Rusts 79

III
IV CONTEISTTS

Page

79

79

79

80

81

Appendix °^

Common and scientific names of trees and shrubs

mentioned ^^

Safety rules and precautions for handling, mixing, and

applying chemicals ^^

Nursery protection—Continued

Nursery diseases—Continued

Nematodes

Dieback

Root rots

Mammals and birds

Literature cited.

Appendix—Continued P(^}e,

Spray formulas for insecticides and fungicides 90

Mouse baits 91

Sources of information on nursery problems 92

Sources of information on nursery machinery, equipment, and chemicals 92

Requirements and procedures for nursery stock inspection in the Plains States 92

U.S. Department of Agriculture forest tree seed policy

(1939) 93

Where to purchase seed 93
INTRODUCTION

The Prairie-Plains occupy a broad belt of highland

between the Rocky Mountains and the Central Lowland. The region extends from San Antonio, Tex., to

about Edmonton, Alberta, and Saskatoon, Saskatchewan. Included are the Great Plains proper, a region

mostly west of 100° longitude with high altitude, semiarid climate, and short grass vegetation ; and the prairie

region, an area of tall grass bordering the eastern deciduous forest. In this essentially treeless area, farmers

and ranchers need windbreaks to protect their buildings, livestock, and crops. Townspeople need trees

along their streets and in their parks to beautify their

cities and to provide shade.

Tree planting began in the Prairie-Plains just after

the first settlers arrived. Many problems of tree establishment confronted the early planters. These included

low annual precipitation, frequent high winds, unfavorable soils, and lack of knowledge concerning the

adaptability of tree species to Plains conditions.

Over the years, from research and practical experience, many of the difficulties have been gradually

overcome. For example, information is now available

on what species to plant and how to plant and maintain the trees.

The growing success of tree planting has increased

the demand for deciduous and coniferous planting

stock. Meeting that demand will require the best

nursery practice that experience and research can

provide.

This manual summarizes available information on

Plains conifer nursery practice and recommends to

nurserymen specific methods for nursery stock production. It will supplement but not replace a bulletin

published in 1941, ^'Nursery Practice for Trees and

Shrubs Suitable for Planting on the Prairie Plains"

(U.S. Dept. Agr. Misc. Pub. 434), a publication concerned primarily with deciduous stock production.

Some operations are fairly standardized, while others

allow the nurseryman more choice of methods to fit his

own situation. Both mechanized and hand methods

required in producing trees are presented. Greatest

emphasis is on methods suited to large-scale production.

Manually operated devices, many developed by the

large nurseries during mechanization, are described to

meet the needs of small nurseries.

NATIVE CONIFERS

The natural stands of trees and shrubs in the PrairiePlains are outliers of the Rocky Mountain forests on the

west and of the Lake States, Central, and Southern

forests on the east. Though their acreage, distribution,

and number of species are not great, these stands have

been important in reforestation in the Prairie-Plains

because they have provided a source of seed from plants

adapted for growing in this region.

Some conifers in the Prairie-Plains, such as ponderosa pine, eastern redcedar, and Rocky Mountain

juniper, are distributed widely (fig. 1) .^ Others, such

as pinyon, limber pine, lodgepole pine, white spruce,

and blue spruce, have more limited distribution. Most

of this natural growth is in breaks, bluffs, and escarpments of rough topography at the higher elevations of

the western Great Plains (fig. 2). The localities of the

most important species are described briefly below,

ipor scientific names of trees and shrubs discussed, see

^Audiority cited and dates enclosed in parentheses, as in

the caption for figure 1, refer to items m Literature Cited,

p. 81.
AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

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FIGURE 1.—Natural distribution of some important conifers

in the Prairie-Plains. The approximate boundaries of the

Prairie-Plains and the Black Hills are indicated by heavy

black lines. The range of eastern redcedar {Juniperus

virginiana) is shown by a dashed line and that of Rocky

Mountain juniper (/. scopulorum) by a solid line. Detailed distributions are identified as follows: PP—ponderosa pine, L—limber pine, P—pinyon, LP—lodgepole

pine, J—junipers other than those above, S—white spruce,

and D—Douglas-fir. (Albertson 1940, Bray 1904, Cockerill et al. 1939, Curtis and Lynch 1957, Herman 1958,

Hutchison and Kemp 1952, Livingston 1949, Nienstaedt

1957, Potter 1952, Stoeckeler 1952a, U.S. Forest Serv.

South. Forest Expt. Sta. 1940, Ware 1936, Warner and

Chase 1956, Williamson 1957, and Woodin and Lindsey

1954.)

Ponderosa pine.—Ponderosa pine is the most widely

distributed of the pines. It is the main species of the

Black Hills, and it is found in all of the Plains States

but Kansas. At its easternmost extension in Nebraska,

it appears in the canyons, on the rough stony land of

the Pine Ridge escarpment, and in the Niobrara and

Upper Platte River drainages. Isolated groves occurred as late as 1885 in the valleys of the Dismal,

Calamus, North Loup, South Loup, Lodgepole, and

Republican Rivers (Bessey 1895). In South Dakota,

ponderosa pine is found in the Black Hills, in the

northwest comer of the State in Harding County, and

scattered over the hills of Shannon, Todd, Washabaugh, and Bennett Counties (Over 1932). It occurs

in three southwestern North Dakota counties in the

Badlands. In east-central Colorado, ponderosa pine

extends eastward on the Platte-Arkansas Divide

(Weaver and Albertson 1956). It also occurs associated with pinyon in the extreme northwest comer of

Oklahoma.

Other pines.—Limber pine is found in southwestern

North Dakota, the Black Hills of South Dakota, the

extreme southwestern comer of Nebraska, southeastern

Wyoming, and the adjoining portions of Colorado.

Pinyon occurs in northeastern New Mexico, southeastern Colorado, and northwestern Oklahoma.

Lodgepole pine is found very locally in the western

part of the Black Hills and in the Cypress Hills of

southwestern Saskatchewan.

Some Southeastern pines, while not found in the

Prairie-Plains, grow on dry situations adjacent to the

region. Included are shortleaf pine in eastern Oklahoma and eastern Texas, loblolly pine in a small area of

southeastern Oklahoma and in eastern Texas, and

longleaf pine in eastern Texas.

Junipers.—Eastern redcedar and Rocky Mountain

juniper are the juniper tree species found most commonly in the Prairie-Plains. Both range from the

southern limits of the Prairie-Plains into Montana and

North Dakota in the north. Eastern redcedar predominates on the east and Rocky Mountain juniper on

the west. The ranges of the two species overlap in

central South Dakota and central and northwestern

Nebraska. An area of natural hybridization has been

delineated, but the degree to which this represents the

overall situation is unknown (Fassett 1944). The two

species may occur in stands together. In eastern

Texas, eastern redcedar is found on dry, gravelly ridges

and limestone hills (Jones et al. 1932). Other juniper

tree species include one-seed juniper in western Texas,

New Mexico, and extreme western Oklahoma (Little

1950) ; Pinchot juniper in central, northwestern, and

Trans-Pecos Texas and in western Oklahoma (Jones

et al. 1932) ; alligator juniper in Trans-Pecos Texas

(Jones et al. 1932) ; and Ashe juniper in northeastern

and southern Oklahoma and on the Edwards Plateau

in central Texas (Hall 1952).

Spruce.—White spmce is generally found in the valleys of the Black Hills of South Dakota. Outliers also

occur in south-central Manitoba and southwestern

Saskatchewan. Blue spruce has been reported in the

Big Horn Mountains in south-central Montana.

Douglas-fir.—Douglas-fir occurs on the Piney Buttes

(Garfield County) in eastern Montana in an area

where the mean annual precipitation is about 12 inches

and minimum temperatures may drop to —58° F.

(Stoeckeler 1952a). Trees from this source have been

used to a small extent in North Dakota plantings.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS

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FIGURE 2.-Natural stands of conifers in the Prairie-Plains: A, Eastern redcedar near Sargent Nebr. (ponderosa P^e and

bur oak are associates) ; B, ponderosa pine in southwestern North Dakota on breaks of Little Missouri River. The pme

has moved out into the grassland since fires have been controlled.
AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

HISTORY OF CONIFER PLANTING

The planting of conifers for other than ornamental

uses began many years ago in the Prairie-Plains. Block

plantings of pine in Nebraska are recorded as early as

1873. According to the annual report of the then U.S.

Division of Forestry, special efforts were made in 1898

to introduce conifers into existing plantings. Conifer

nurseries had been established at several locations, and

in 1898, 300,000 conifers had been distributed to

farmers in quantities sufficient for 1- to 5-acre plantations. Despite these early efforts, few of the conifer

plantings established before 1935 are extensive enough

to allow planters to compare their performance with

that of hardwoods in protection plantings. Coverage

of the Plains was incomplete, and some species had

little representation in some localities. A notable

exception is block plantings of conifers started in 1904

on the Nebraska National Forest in the sandhills region

(fig. 3).

Conifers were planted over a wide area of the

Prairie-Plains by the Prairie States Forestry Project.

Included in the 18,600 miles of shelterbelts planted

between 1935 and 1942 under a great variety of climatic and soil conditions, these trees have been one of

the main sources of information on the performance of

various evergreen species in the Plains. An appraisal

made in 1954 (Read 1958) of 938 shelterbelts from

North Dakota to northern Texas showed that conifers,

when once established, survived well throughout the

survey area. Eastern redcedar was the hardiest tree.

Ponderosa pine and Austrian pine showed good

drought resistance and staying power despite initial

survivals of less than 50 percent. Other species used

by the Project were Rocky Mountain juniper, alone

and with eastern redcedar, from North Dakota to

Oklahoma; blue spruce and white spruce in the Dakotas; and jack pine and Scotch pine in South Dakota,

Nebraska, and Kansas. Shortleaf and loblolly pines

were used in the plantings of southern Kansas, Oklahoma, and Texas.

Austrian and Scotch pine have been widely planted

in the Prairie-Plains. Austrian pine grows slower than

ponderosa pine in Texas (Jones et al. 1932) and in

Oklahoma (Afanasiev 1949a). It has been difficult

to establish in North Dakota. Scotch pine has exhibited early rapid growth but is short lived and is

more subject to mortality by drought.

F-392988

F.GURE 3.-This forest plantation of jack pine in the sandhills of the Nebraska National Forest wa. large enough by 1940

to produce posts and small poles.
CONIFER NURSERY PRACTICE m THE PRAIRIE-PLAINS

Shortleaf pine has been planted in windbreaks in

western Oklahoma (Afanasiev 1949b). Some loblolly

pine, Japanese red pine, and Japanese black pine are

used in eastern Oklahoma. Japanese black pine has

been a fast grower, faster than all pines but shortleaf

pine, and has a low susceptibility to tip moth damage.

Japanese red pine has poor form, with multiple stems,

and is highly susceptible to tip moth damage. Jack

pine and eastern redcedar have been planted extensively and quite successfully in Nebraska, particularly

in block plantings in the sandhill region.

Arizona cypress, a native of western Texas, New

Mexico, and Arizona, has been used with great success

in Texas and Oklahoma for windbreak and ornamental plantings. Trees of this species are tender while

young but have withstood temperatures as cold as

10° F. when older (Jones et al. 1932). The form

from central Arizona, called smooth Arizona cypress

and characterized by smooth outer bark, is widely

cultivated in warm, dry regions in shelterbelts and as

an ornamental; it also is used for Christmas trees and

fenceposts (Little 1950). Selections of oriental arborvitae are easy to establish and grow fairly fast. They

have proved very hardy and effective in windbreak

plantings.

FUTURE OF CONIFER PLANTING

More hardwoods than conifers have been planted

in the Prairie-Plains. This was only natural. The

Prairie-Plains had little native coniferous growth. Because hardwood planting stock was more available to

planters and grew faster, it appealed more to the

homesteader intent on securing some early protection

for his farmstead. Bare-rooted conifers often dried up

during transportation, and the rigorous climate limited

their establishment after planting.

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However, in the future, conifers will have an increasingly important place in Plains planting programs.

Among their inherent advantages over most hardwoods are year-round foliage retention, greater longevity, lower fertility and soil moisture requirements,

relatively more freedom from insects and diseases, and

the ability after establishment to compete more successfully with weeds and grasses. Conifer needles

remain under the trees, building up a vegetationsmothering and soil-protecting layer of litter that also

increases water infiltration and reduces moisture

evaporation. In a study of tree planting on the drier

sections of the northern Great Plains, it was found that

the coniferous species do not exhaust the soil moisture to as great a depth as do the hardwoods, and that

they establish forest conditions very readily in reasonably full stands (George 1939).

F-502143. 502141. 505888

FIGURE 4—Use of conifers in windbreak plantings on

the Prairie-Plains: A, An 18-year-old planting of shortleaf pine in a field shelterbelt near Vernon, lex.;

B right-angle view of a dense single-row planting of

eastern redcedar, 15 years old and 18 feet high; C,

effective year-round wind protection is provided by

25-year-old ponderosa pine in field windbreak near

Towner, N. Dak.
6

AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

Conifers are well adapted for all protection plantings, whether they be for farmstead, field, livestock,

wildlife, or for multiple purposes (fig. 4). Not only

do they provide year-round protection, but their thick

crowns trap snow, and the trees ofifer less competition

to adjacent crops (Greb and Black 1961). The soft

wood has more value at maturity and is more easily

disposed of than the wood of deciduous trees. Conifers are also particularly suited for ornamental plantings and for use as Christmas trees.

Conifers, of course, have some disadvantages when

compared to hardwoods. It takes longer and costs

more to produce planting stock. The trees are harder

to establish, and because initial survivals in the field

are lower, more replacements are required. Because

they have a slower initial growth and consequently

must compete with grass and other ground cover for

a longer period, more maintenance is needed. Retention of the foliage throughout the year subjects the

trees to excessive drying during periods of near dormancy. Damaging agents, such as fire or livestock,

will reduce growth and may eliminate the trees since

most conifers are unable to sprout or restore foliage.

Reproduction of conifers other than eastern redcedar

rarely occurs in farm plantings. Finally, adapted seed

from natural or planted stands has been hard to obtain

in quantities large enough to handle economically.

Nevertheless, the advantages far outweigh the disadvantages. Furthermore, some of the obstacles can

be overcome. In the drier portions of the Plains the

use of potted trees and more careful handling of barerooted stock from the time of lifting in the nursery

to planting have resulted in higher initial survivals.

Improved machines and methods of tillage have increased both initial survival and growth rates. Increased use of trees grown from seed of established

plantings and of native stands of proven hardiness

should also provide trees that survive better and grow

faster.

COLLECTION AND HANDLING OF SEED

IMPORTANCE OF SEED SOUBCE

There is abundant evidence that conifer seed from

local sources produces planting stock more resistant

than imported stock to loss from drought, insects, and

disease. Foresters and others engaged in tree planting

in the Prairie-Plains generally agree on the importance

of using seed sources adapted to local climate and soil

conditions. However, this requisite too often is

slighted or ignored. Since the advent of large-scale

tree planting on the Plains, a large number of trees

of unsuitable origin have failed or have grown poorly.

Thus, much of the effort spent in seed collection, production of nursery stock, and establishment in the

field has been wasted.

Though seed source research has been less extensive

in the Prairie-Plains than in many other areas, there

are some specific examples of seed source variation

for conifer species grown in the Plains. In a study of

the survival and growth of 25- to 41-year-old trees

of six Scotch pine races under prairie conditions in

Saskatchewan, differences were apparent and seemingly distinctly inherent (Cram and Brack 1953).

Investigators have reported that the growth and survival of ponderosa pine is influenced by racial origin;

they found wide variations in height growth and survival between lots of wide geographic origin and altitudinal zones (Bates 1927, Callaham and Metcalf

1959, Munger 1941, Weidman 1939). In the sandhills of Nebraska, planted ponderosa pine of Nebraska

origm were less damaged by tip moth than were the

trees of New Mexico seed source (Bates 1927). There

was also variation among lots in browsing by deer.

The variability in hardiness of ponderosa pine grown

from seed originating in different climates was evident

m 6-year-old plantings in McHenry County, N. Dak

In March 1946, severe winter injury appeared as the

pine underwent browning and defoliation. - The heaviest damage was sustained by trees with Black Hills

and western Nebraska origins, and the least by trees

grown from seed of the nearest native origins (western

North Dakota and eastern Montana). Again, following the winter of 1947-48, the trees of the near-local

sources showed less foliage injury (Stoeckeler and

Rudolf 1949).

Outstanding performances of the local sources have

been observed many times at the Bessey Nursery,

Halsey, Nebr. Scotch pine from a local collection

produced 2-0 seedhngs nearly twice as large as those

from a central European source. Austrian pine from

seed collected near Lincoln, Nebr., produced stock far

more satisfactory than any Austrian pine previously

grown. In 1955, it was noted that 2-0 ponderosa pine

beds varied considerably by seed origin; the best lot

was from a local collection.

The Nebraska National Forest, with 30,000 acres of

conifer plantings established from 1903 to 1958, is an

outstanding example of a site on which seed of local

origin was used. The first trees planted were wildlings

shipped in from the Black Hills and the Lake States,

but the establishment of a nursery in 1902 soon made

it possible to control the source of stock. In the spring

of 1904, 1-0 ponderosa pine, grov^oi from seed collected in 1902 in northwestern Nebraska, was planted.

The first eastern redcedar seed used was collected in

1912 in a natural stand along the Niobrara River. In

the early 1920's, seed of Austrian and Scotch pine was

collected from ornamental and shelterbelt trees in eastern Nebraska to supplement seed purchased from

Europe. These local plantings have demonstrated

reasonably good adaptation to local conditions.

European countries have much broader experience
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS

than the United States in the harmful effects of indiscriminate use of seed without regard to origin. Some

of them have passed strict laws providing for the certification of the source of seed. There are no Federal

or State laws in the Plains States requiring the use of

forest tree and shrub seeds of known origins. However, certification of tree seed is now possible in South

Dakota under State laws pertaining to cereal, forage,

and oil crops. The International Crop Improvement

Association approved minimum standards for tree

seeds in 1959 and adopted more widely applicable

standards in 1962 (SAF Seed Certification Subcommittee 1963).

In 1939 the U.S. Department of Agriculture adopted

a seed policy that partly requires and partly recommends use of local or well-adapted seed for forestry

and related purposes. It requires tree planting agencies in the Department to use in their planting programs, wherever practicable, seed of known origin

from within 100 miles distance and 1,000 feet elevation of the planting site. It recommends keeping an

accurate record of such seed, including the lot number, year of seed crop, species, origin as to State,

county, and specific locality, range of elevation, and

proof of origin. (See Appendix for entire policy

statement. )

A suggested minimum program for collecting seed

in the Prairie-Plains included the following points

(Engstrom and Stoeckeler 1941) :

1. Zone the seed collection area according to

climate.

2. Limit collection largely to local seed.

3. Pick seed only from healthy and vigorous trees

of reasonably good form.

4. Keep an accurate, permanent record of seed

source from time of collection through field

planting, including proper identification and

labeling of the seed and the place and elevation of collection.

5. Import seed only after giving thorough study

to the experience with seed from different

foreign countries.

SEED COLLECTION ZOIVES AND LOCALITIES

Eleven seed collection zones, based primarily on

latitude, have been delineated for the Prairie-Plains

(fig. 5). It is recommended that seed be collected and

the progeny planted within the same zone. Where

absolutely necessary it is permissible to move seed or

stock from one zone to an adjoining zone. Compensating factors such as elevation would permit movement of seed northward across one or two States.

Thus, blue spruce seed can be moved safely from the

higher western part of the more southern seed zones

in Colorado and Wyoming to northern North Dakota

(Engstrom and Stoeckeler 1941). A little movement

to the north may result in reasonably hardy trees that

grow slightly faster than trees of local origin. These

zones were based on observation and experience and

proved workable in the Prairie States Forestry Project

It is recommended that they be used until research

discloses a better basis for zonation.

Trees from northern seed planted farther south

generally sunave fairly well; however, they may grow

slowly, develop poorly, and eventually succumb to

drought and heat. If the northern stock buds out on

the first warm days of spring, the new growth may be

damaged by frost. When trees grown from southern

seed are used too far north, they may soon die because

they lack the hardiness and early ripening of wood

necessary to withstand the northern winters (Engstrom

and Stoeckeler 1941).

Movements from east to west—that is, generally to

drier climates—appear less harmful than latitudinal

movements but should not be encouraged (Engstrom

and Stoeckeler 1941).

Although the seed collection zones shown in figure 5

are generally applicable to most conifer species in the

Prairie-Plains, more specific localities can be given for

collecting seed of a few species in certain areas. Ponderosa pine seed should be collected from the more arid

portions of its range bordering the Plains. Good

FIGURE 5.—Seed collection zone map for the Prairie-Plains.

Broken lines separate the zones (Engstrom and Stoeckeler

1941).
8

AGRICULTURE HANDBOOK 2 7 9, U.S. DEFT. OF AGRICULTURE

sources in Nebraska are the Pine Ridge and Niobrara

River areas; in South Dakota, the northwest and on

the Rosebud and Pine Ridge Indian Reservations in

the southwest; in North Dalcota, the southwest; and

in Montana, the extreme east. Seed from the foothills

of the Black Hills has been used rather extensively

because the quantity of seed produced is greater and

more reliable than in other collection areas. Further

study will be needed before this source can be fully

evaluated, but it seems likely that at least some Black

Hills seed can be used with confidence in Nebraska and

to the north. Eastern Colorado sources seem best for

use in Kansas and to the south.

Seed collections of Rocky Mountain juniper and

eastern redcedar should be made as near the latitude

of the planting site as practicable.

Rocky Mountain juniper should be collected in

North Dakota along the Little Missouri River near

Medora, in northwestern South Dakota, and in

extreme eastern Montana.

Seed of eastern redcedar should be collected in South

Dakota from the bluffs of the Cheyenne River and

from other native stands. However, seed collected

along the Platte River in Nebraska does reasonably

well in South Dakota (Hansen 1930). In Nebraska,

eastern redcedar sources in and adjacent to Custer,

Loup, Blaine, and Brown Counties have produced stock

better suited to statewide planting than seedlings of

Platte Valley origin. Collections of redcedar along

the Cimarrón River have proved well adapted to Oklahoma planting sites.

In the prairie provinces of Canada, spruce seed

collected from older specimens in windbreaks of the

nurseries at Indian Head and Sutherland and from

natural stands in Manitoba and northern Saskatchewan have produced stock adapted to Canadian conditions (Ross 1937). Generally, common commercial

seed has not proved hardy.

SELECTIOX OF INDIVIDUAL STANDS AND

TREES

Next in importance to using seed from local sources

is collection from selected stands and individual trees

with desirable characteristics. Tree improvement

studies of forest trees have revealed wide variations

between individuals of the same species (fig. 6).

Superior trees with desirable characteristics should be

noted, and their location should be recorded.

Some traits of value in windbreak and shelterbelt

trees are tolerance of drought conditions, ability to

grow on alkaline soils, and resistance to snow, wind,

and glaze injury (Rudolf 1956). Other desirable

characteristics are compactness, resistance to insects

and disease, and rapid growth without spindliness.

Trees and stands that are superior in growth characteristics should be used for seed collection as much

as possible. Cones obtained from squirrel caches may

be of good genetic character only if the stand as a whole

is composed of trees of good form.

F-49311t

FIGURE 6.—A row of 21-year-old ponderosa pine in the

North Dakota State Nursery at Towner, McHenry County,

N. Dak. The differences in height growth, broadness of

crown, density of foliage, and angle of branching illustrate

the wide variation between individuals of the same seed

source.

If block plantings are being considered for wood production, the form and height of the parent tree and

quality of the product must also be considered. Lumber from ponderosa pine growing on the hills along

the Little Missouri River northwest of Amidon, N.

Dak., reportedly was brash and inferior to lumber cut

from trees about 35 miles distant in the Long Pines or

Ekalaka Divisions of the Custer National Forest in

Montana. Of course, it is not known whether these

differences stem chiefly from genetic or acquired

characteristics.

Seed orchards should also be established from the

material of carefully selected stands. Seed orchards of

hardy and desirable form of oriental arborvitae and

Arizona cypress have been established in Oklahoma.^

Similar developments are likely to be planted in other

Prairie-Plains States.

DETERMINATION OF SEED RIPENESS

AND QUALITY

The soundness of seeds by locality or even by plant

should be tested before extensive collecting is done.

Seed viability may vary considerably among stands and

trees. Seeds from each tree can be tested quickly by

cutting them open with a small wire nipper and seeing

whether they are filled. This practice, carefully followed, will eliminate trees with many weeviled and

hollow seeds before considerable labor and money are

expended.

° Personal communication with E. W. Johnson, Agricultural Research Service Field Station, Woodward, Okla.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS

The ripeness of seed must also be judged during collection, since immature seed does not keep as well as

ripe seed in storage and is of lower germination

capacity (Engstrom and Stoeckeler 1941). Seedlings

from immature seeds are smaller and less vigorous

than those from mature seeds (Tourney and Korstian

1942 ). Cutting tests are also recommended to estimate

seed maturity. The kernel of a mature seed is firm

and white or cream colored, and fills the cavity

completely.

Ripening dates of a species vary by season or locality

because of local climate. Therefore, frequent inspections may be required to determine in advance the approximate ripening dates. Failure to closely observe

the progress of ripening for species that hold their seed

for only a few days after maturity, such as limber pine

and oriental arborvitae, may result in loss of the crop.

The seed of Rocky Mountain juniper takes 2 years to

mature. One-year fruit is light green as compared to

the light blue of the mature fruit. It should not be

collected since the green and mature berries are hard

to separate. No collections should be made from trees

with large amounts of green berries.

In Nebraska, under dry conditions, ponderosa pine

cones can usually be collected directly from the trees

only during the 2 to 3 weeks between the time proper

ripeness is reached and the opening of cones on the

trees. The seed of Austrian pine ripens 2 weeks later

than that of ponderosa pine; the cones remain closed

longer, sometimes through the winter.^

Ponderosa pine cones are ripe enough to collect when

their specific gravity in place on the tree has dropped to

0.85, or when a majority of five sound, freshly picked

cones will float in kerosene. The time of squirrel collection is not a reliable index of seed ripeness since

they often cut the cones 3 to 4 weeks in advance of

seed maturity. Color also is not a rehable index of

cone ripeness (Maki 1940).

Spruce cones are ripe enough to collect when the

seed coats darken and the kernels become firm (U.S.

Forest Serv. 1948). In a study of seed maturity of

planted spruce in Saskatchewan, it was recommended

that collection of blue spruce cones be delayed until 90

percent or more freshly picked cones float in linseed

oil, which has a specific gravity of 0.94 (Cram 1956a).

For white spruce, collection is recommended when 90

percent or more freshly picked cones float in turpentine

(Cram 1957).

The berries of eastern redcedar. Rocky Mountain

juniper, and oldfield common juniper are dark blue

when ripe. However, they are usually coated with a

powdery bloom; therefore, they appear light blue.

For a further discussion on the seed ripening process

and the time to collect, refer to the "Woody-Plant

Seed Manual" (U.S. Forest Serv. 1948).

^ Personal communication with M. K. Meines, Superintendent, Bessey Nursery, Halsey, Nebr.

SEED CROP FREQUENCY

The size of seed crops will vary from year to year,

depending on several factors. Among the most important are the climatic conditions during flowering,

seed formation, and ripening; the damaging effect of

insects and rodents; the age of the seed trees; the size

of the flower crops; and the inherent ability of the tree

or species to produce seed. Seed may be destroyed by

insects that attack the buds, flowers, and immature

cones, as well as the seed itself (Lanquist 1946). Seed

production by eastern redcedar is often reduced by

late spring frosts which damage the female flowers.

No periodicity in seed crops has been noted in ponderosa pine (Curtis and Lynch 1957). Observations

over 23 years east of the Continental Divide in Montana showed this species to be a poor seeder—only

one good seed crop occurred (Boe 1954). Two good

crops, two fair ones, and five failures were recorded

during a 9-year period in the foothills of the Rockies

in eastern Colorado (Roeser 1941 ).

Junipers produce more good seed crops. Particularly heavy crops of Rocky Mountain juniper seed are

produced every 2 to 5 years, and some seed is borne

nearly every year (Sudworth 1915). Eastern redcedar

produces good crops every 2 to 3 years in Oklahoma

( Afanasiev and Cress 1942a). The same frequency of

good seed years occurs at Halsey, Nebr., where nine

good seed crops of eastern redcedar were recorded in

windbreak plantings between 1929 and 1956. Seed

production of trees in windbreak plantings may differ

from that of trees in wild stands because of dissimilar

growing conditions and parentage.

Availability of seed in the quantities necessary to

fill nursery seeding and planting quotas must also be

considered along with the climatic adaptability of any

source or "strain." Some species set a good crop of

cones at infrequent intervals. Usually some seed is

produced in other years, but it is generally scattered

and is often so poor that the cost of a pound averagmg

50 percent or more in germination may be three or

four times as high as seed collected in a good seed year.

Since most seed retains its viability well when stored

properly, it is good to provide for the future in years

when a good supply of high-quality seed is obtamable.

SEED YIELDS

Complete records on seed yields of species commonly

used in Prairie-Plains tree planting are available m the

''Woody-Plant Seed Manual" (U.S. Forest Serv.

1948) However, localized information on yields is

desirable since some widely used species have extensive

ransfes outside the Plains.

Data on the seed yield of ponderosa pme, eastern

redcedar, and Rocky Mountain juniper in native

stands of the Great Plains were obtained pnmanly

from the B.essey Nursery records, which cover a period

of more than 50 years (tables 1 and 2). Collections

were made in most years. The range in yields is perhaps wider than would normally be expected, and resulted indirectly from the policy of the Nebraska
10 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

TABLE 1.—Ponderosa pine: yield of freshly collected, cleaned seed in native stands of the Great Plains

Locality

CoUections

Yield per bushel of

cones

Seed per pound

Average Range Low High Average

Nebraska ^

Number

1

3

6

Ounces

20

20

Ounces

13-36

18-22

Number

8,200

13,400

12, 600

Number

11,500

16,600

19, 300

Number

9,700

Black Hills 14, 600

Eastern Montana ^ 15 700

^ Seed from stands along the Niobrara River at Pine Canyon in Custer County and from one collection on the Rosebud

Indian Reservation in South Dakota.

2 From collections at Fallón, Glendive, and Jordan, Mont.

3 Data not available.

National Forest of collecting as much seed locally as

was possible. Also, the berries or cones occasionally

yielded little viable seed, owing to insect infestations

or other causes.

The yield of ponderosa pine varies from 13 to 36

ounces per bushel for Nebraska cones, and from 18 to

22 ounces for cones from the Black Hills (table 1).

Average yields, 20 ounces per bushel of cones, are

about the same for the two sources.

The low yields of eastern redcedar in Nebraska

represent collections in years when the seed crop was

poor and insect infested (table 2). The larger yields

are for good to excellent seed years.

Now that many planted stands are bearing seed,

the nurseryman has a much wider selection of parent

trees from which to collect. Seed collection from

mature stands or from those of known seed origin is

preferable.

Redcedar berries have been collected for many years

from a windbreak 60 years old at Anselmo, Nebr. The

trees are probably of natural origin and have produced

as much as 80 pounds of berries per tree. At Anselmo

an experienced man can pick an average of 40 pounds

of berries per day in years of good to excellent crops.

Few records are available for seed production in

planted stands of conifers in the Plains, but there is a

partial record for such stands on the Nebraska

National Forest (table 3).

This record indicated that planted stands will yield

good seed in economical quantities whether they be

in block plantings or in individual rows of shelterbelts.

The yield of ponderosa pine seed in plantations at Halsey, Nebr., an average of 20 ounces per bushel of

cones, compared very well with that of native stands.

Austrian, Scotch, and jack pine from local sources provided a supply of good-quahty seed from acclimated

trees. The seed tended to be larger than that obtained from the native sources of the three species.

Some seed was produced on Scotch and jack pine trees

less than 20 years old, but substantial quantities were

not produced from Scotch, Austrian, and ponderosa

pine until they were 25 to 30 years old. In Oklahoma,

Johnson^ noted that Austrian pine does not produce

much seed before the trees are 20 years old.

The number of seed per pound also varies consid-

* Personal communication with E. W. Johnson, Agricultural Research Service Field Station, Woodward, Okla.

TABLE 1.—Juniperus: yield of newly collected, cleaned seed in natural and planted stands

Species and locality

Eastern redcedar:

Nebraska, planted i

Nebraska, natural stands 2

South Dakota, natural stands

Oklahoma, natural stands

Rocky Mountain juniper:

South Dakota, Nebraska, Wyoming, and Montana

natural stands. *

Collections

Number

20

9

3

12

' Planted windbreaks at Anselmo and Halsev Yield«!

based on 27,000 pounds of berries ^'

2 Yields based on 9,439 pounds of berries.

Yield per 100 pounds

of berries

Average

Pounds

15.3

16.2

17.5

14.0

19.8

Range

Pounds

4-20

3-18

14-19

7-16

11-28

Seed per pound

Low

Number

37, 200

37, 000

42, 200

22, 000

High

Number

55, 000

53, 300

46, 100

32, 000

' Data not available.

^ Yields based on 3,637 pounds of berries.

Average

Number

43, 200

42, 800

43, 400

27, 200
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS H

TABLE 3.—Pinus: yield of newly collected, cleaned seed in planted stands, Nebraska National Forest

Species

Ponderosa pine

Austrian pine '

Scotch pine . . .

Jack pine

Collections

Number

Yield per

bushel of

Ounces

23-24

6-15

6-12

6-13

Seed per pound

Low

Number

10,200

14,000

42, 200

74, 100

High

Number

12, 200

22, 800

57,100

85, 300

Average

Number

11,200

18,500

48, 100

79, 100

' Seed from stands near Lincoln, York, and Oakland, Nebr., averaged 20,300 per pound.

erably, depending on the locality of the collection, season, and degree of dryness. Fresh seed tends to be

heavier than seed that has been stored over a period

of years, so averages are given for newly collected seed.

Conifers are sometimes depredated by cone- and

seed-eating insects. The cone moth Dioryctria auranticella (Grote) was noted at Halsey in 1928, about the

time when ponderosa pines were first starting to bear

cones. This insect is common in native ponderosa

pine stands in adjacent areas of Nebraska and South

Dakota. Blue spruce cones have been damaged in

southern Saskatchewan by the spruce coneworm {D.

reniculella) (Grote) and those of white spruce by the

s^truce. sc^àmoûi Laspeyresia youngana (Kft.) (Peterson and Worden 1959). Other insect enemies undoubtedly are also present.

METHODS OF SEED COLLECTION

Seed collection in the Plains often involves much

travel over widely scattered areas and use of special

collecting equipment. The equipment necessary for

efficient seed collection varies by species. However,

nursery labor and equipment can be used to make

local seed collections of some species. For a season's

work on various species, collection crews should be

equipped with wire nippers or side cutters for field

cutting tests and other purposes, cutting hooks for detaching cones (fig. 7), ladders, picking bags, baskets,

sacks, tags, twine, ropes, linemen's safety belts, goggles, hardhats, heavy leather gloves, and tarpaulins

or seed sheets.

A nursery practice handbook, based on many years

of experience at the Bessey Nursey, contains the following suggestions for seed collection in planted and natural stands of conifers.

Purchased seed should be obtained from a reliable

collector or seed dealer who will guarantee the collection area and year of collection (see "Where to Purchase Seed," in appendix).

The foremen define the seed collecting areas and

select individual trees desirable as to age, tree form,

and other characteristics. Pickers work in pairs to

facilitate the movement of the ladders and other equipment from tree to tree. Man-day production is greater

when trees of low yield are bypassed. Collection

methods to be used depend on the characteristics of

each species.

Because they are borne mostly on the branch tips,

¡Mnderosa pine cones can be picked more efficiently

from ladders than by climbing the trees. For safety,

pickers should carry a short rope on the top rung of

F-342209

FIGURE 7 —A cutting hook for detaching fruit, cones, or small

limbs from trees; it is made from two mower blades welded

to a flat piece of steel 8/2 inches long.
12 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

the ladder and tie the ladder to a stout branch or to

the tree bole. Cone hooks are used to bring coneladen branches toward the picker and to cut loose

cones beyond arm reach. The cones usually are

dropped and picked up later. In the well-stocked

stands of the Black Hills, ponderosa pine cone collections can be made from squirrel hoards.

Austrian pines are easier to climb than ponderosa

pines, and the cones come off easier. Serotinous jack

pine cones have been collected from branches removed

during pruning and thinning. Limber pine tends to

op>en its cones rapidly, and the wingless seed may fall

to the ground. However, the seed will remain in the

open cone on the tree for a few days if there is no

wind, and much of it can be saved by spreading tarpaulins under the tree before the cones are picked.

When the picker is working on the ground or on low

ladders, the cones are put in a sack worn around the

neck.

Juniper berries are collected on the Nebraska Forest

by stripping them directly into picking bags or baskets

strapped to pickers, by rubbing or stripping them into

tarpaulins spread under the trees (fig. 8), or by a

combination of these methods. The branch is taken

between the hands, and near its end it is rubbed with

a rolling motion. Part of the debris can be removed

while the fruit is still on the tarpaulins by shaking them

to bring the coarse material to the surface.

An alternate method, one of those used in cold

weather, is to beat the frozen berries from the branches

with a stick 12 to 18 inches long and 1 to 2 inches thick.

The end of the stick is padded with several layers of

burlap.

Quite often more than half the tree seed can be

reached from the ground, and the rest can be gathered

from short ladders. If the crop is good, the tree need

not be picked clean. When good seed trees are few,

the older and taller trees may furnish most of the

good seed, and taller ladders are needed.

Tarpaulins are not used in brushy areas or on steep

slopes. Here, bags with open-hooped mouths are hung

from the neck. The use of strippers mounted on poles

has damaged trees and resulted in an accumulation of

much trash among the seed.

.»v..', > ^-^ --* f'^tv^-'^ ^^ü..W€ú

FIGURE 8.—Collecting eastern redcedar berries from F-334697

natjve trees in the Platte River Valley near Fremont, Nebr.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 13

The seed of oriental arborvitae and some Arizona

cypress is obtained from planted trees. The seed of

oriental arborvitae must be picked promptly when

the cones begin to open and before the small seed falls

to the ground. The cones of Arizona cypress remain

closed on the tree, permitting a longer period for

collection.

CARE OF FRESH SEE»

Seeds of most conifers are not dry enough to be

stored immediately after collection. They must receive adequate aeration or be placed in a dry atmosphere. If the seed cannot be extracted immediately,

the freshly gathered fruits should be spread in a thin

layer in a dry place in the open and stirred occasionally

for several days following collection. Freshly picked

pine cones and juniper berries heat rapidly if left in

sacks or deep piles. Therefore, layers of fruit should

not be more than 2 to 4 inches thick. After drying,

the fruits can be stored temporarily in bags while

awaiting extraction.

Where ,cone storage sheds are available, the cones

can be stored in trays for drying prior to extraction

of the seed (fig. 9).

SEED EXTRACTIOIV AND CLEANING

A modem seed extractory is desirable if the size of

the nursery and its production schedule require large

quantities of pine or spruce seeds. Less elaborate

facilities suffice when smaller quantities of cones are

to be handled. At Norman, Okla., up to 60 bushels

of loblolly and shortleaf pine cones can be handled

per day in a 25- by 25-foot cone-drying room. This

drying unit is heated by gas (a 112,000 B.t.u. heater).

Cone trays with a screen-wire bottom are made from

2 by 4's.

F-4889I5

FIGURE 9.—^A cone storage shed at Big Sioux Conifer Nursery, Watertown, S. Dak. The cone storage portion of

the building on the right is connected directly to the

extractory.

748-005 O—65——2

F-502087

FIGURE 10.—Ponderosa pine cones placed on racks for extraction. Tarpaulins are used to prevent the loss of seed

as the cones open. Bessey Nursery, Halsey, Nebr.

Although artificial heating results in greater extraction of the seed, solar heat and air drying often are

satisfactory. The cones are placed out of doors in the

sun on screens or tarpaulins (fig. 10). When open,

they are shoveled into a screened tumbler; the seeds

fall to the floor from one end of the tumbler, and the

empty cones discharge from the other end. Further

recovery of seed remaining in the cones can be secured

by threshing them in an improvised combine or low

revolution-per-minute hammermill. The efficiency of

the solar extraction can be raised materially by allowing

the cones to remain on the trees almost to the time of

natural seed fall.

- Fresh cones that have been predried in the sun will

open readily; cones that have been stored may not.

Maki (1940) found that cones fail to open satisfactorily when they have been dried out gradually in cool,

dark places or have been stored in sacks and other containers where the scales could not open. Cones that

have been stored long enough to become dry without

opening may have to be moistened before they will

open satisfactorily.

Dewinging of ponderosa pine seed is simplified by

wetting. The seed is sacked and dipped in water long

enough to swell the wing collars, or loose seed is spread

in layers one-half to 1 inch deep and moistened. The

seed is then placed on screens to dry with occasional

stirring. When sufficiently dried, the wings are loose

and can be fanned out.

Small quantities of dry seed can be dewinged by

rubbing them in a cloth sack and then winnowing.

For large quantities, some type of mechanical dewinger

is needed. Lanquist (1954b) cleaned and dewinged

seed in a machine adapted from a dustless hammerrnill

that was designed by the Soil Conservation Service

(Steavenson 1940). The hammers of the mill are
14 AGRICULTURE HANDBOOK 279, U.S. DEPT. OF AGRICULTURE

replaced by a brush arrangement for dewinging the

seed. The screen size depends on the seed size. With

a brush speed of 184 r.p.m., almost all of the wings are

removed in one operation. The mechanical dewingers

must be used carefully to avoid injury to the seed (U.S.

Forest Serv. 1948).

Seed extraction for the juniper species is mostly a

process of running the berries through a fanning mill

to remove foliage and other trash, macerating the

berries, and removing the pulp residue by flotation and

screening. Numerous types of macerators have been

successfully employed.

A macerator developed by the Forest Service is often

used (fig. 11). It is of all-metal construction and is

built on the principle of a threshing machine with

cylinder and concaves. The capacity of the macerator is governed by the length of the cylinder, which

varies from 12 to 18 inches. The machine may have

fixed plates, but adjustable macerating plates are available so that different clearance widths can be obtained

for the various types of seeds processed. A good power

unit for operating this machine is a 1-hp. electric motor

or a small gasoline engine. Commercial models which

operate similarly are also available.

The machine is run at a rather high speed, with the

discharge slide wide open to thresh the fruit from the

leaves and twigs. The seed is separated from the pulp

by closing the discharge opening and decreasing the

speed. This machine, equipped with a 12-inch cylinder with teeth spaced to provide three-eighth-inch

clearances, has handled 1,000 to 1,500 pounds of juniper berries per day (Engstrom and Stoeckeler 1941 ).

At the Bessey Nursery, a large meat grinder is now

used. The grinder is electrically driven and operates

in a normal manner, except that the cutting blade is

reversed on the shaft to prevent injury to the seed as

F-502088

FIGURE 11.—Maceräüng juniper berries in a specially contl""" u^'^u^^"'^''"'- The machine can also be used to

i^K Î,- u^ "' l^^'"''^' ^"'^ tw'g^ by operating it at a

rather high speed, with the discharge slide wide open.

the berries are forced through the disk sieve. The

berries can be run through the grinder as fast as one

man can fill the grinder and handle the pulp. For

complete maceration, they are run through the grinder

two or three times without water.

A hammermill was used extensively by the Soil Conservation Service nurseries to extract juniper seed.

The mill was run at a speed of about 400 r.p.m. by a

farm tractor with a flat-belt drive. The fruit was

poured into the mill, and ample quantities of water

were supplied by one or two garden hoses ( Steavenson

1940). After 14 to 20 minutes of treatment, the clean

seed had collected on a screen in the bottom of the mill.

This material was then dumped on screens to dry.

Finally, it was run through the fanning mill to separate

the seeds from the debris.

After most maceration processes, the seed usually

needs further cleaning. First the mixture of seed and

pulp is soaked for 1 or 2 days in a lye solution ( 1 teaspoon of lye to 1 gallon of water). This separates the

seed from the remaining pulp, which is very oily and

resinous, and which would hinder seed washing and

flotation and subsequent seed stratification. After the

lye treatment, the mass is dumped into screened trays

and thoroughly washed by forcing water through it

under pressure to remove the lye and most of the

remaining pulp; only the berry hulls and seed are left.

The sound seed can usually be separated from the

berry hulls and from floaters (empty or light seed) by

flotation (Engstrom and Stoeckeler 1941). This

method is based on variation in buoyancy imder agitation in water. Some of the macerated material is

placed in a slightly tilted large washtub into which a

stream of water from a garden hose is directed at such

an angle as to create a rotary swirl and a lifting eflfect

on the material. Slight stirring of the material in the

bottom of the tub is also necessary. The pulp and

light seed will float to the surface and spill over the

edge of the tub as the water overflows. The seed is

then dried on tarpaulins in the sun or on trays in the

extracting room. Finally it is fanned to remove the

remaining empties and small seeds.

After extraction, the moisture content of seeds should

be determined, particularly that of conifer seeds scheduled for several years' storage. The preferred moisture content of seeds used in Prairie-Plains nurseries is

detailed in the following section on seed storage.

Kiln-dried or air-dried seed from dry climates often

need no additional drying. Wahlenberg (1925)

recommended that, when possible, ponderosa pine seed

should be dried at ordinary temperatures instead of in

a kiln. A seed drier may be used to dry seed following

extraction, especially during winter when air drying

outdoors is not feasible and inside drying space is limited. A rotary drier, consisting of a screen-wire

cylinder 32 inches long and 32 inches in diameter with

wooden ends of one-half inch limiber, has been used by

the Forest Service (Engstrom and Stoeckeler 1941).

The three 1- by 3-inch baffleboards, equally spaced

within the periphery of the cylinder, pick up the seed as
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 15

the drum revolves and slowly spill it in a thin stream

as each baffle reaches the highest point. Warm air

from the heater^ forced through a revolving cylinder

by an electric fan, hastens the evaporation of moisture

from the seed. The optimum speed for the cylinder is

12 to 15 r.p.m. There is danger, however, of too rapid

or excessive drying.

SEED STORAGE

Because of the irregularity of conifer seed crops,

it is essential that stocks of seed be kept for several

years. Lack of knowledge on proper storage conditions

resulted in heavy losses during early reforestation

efforts. Therefore, extensive research has been done

on seed storage.

One of the two critical factors is moisture content

of the seed. Satisfactory ranges or levels of moisture

content prior to storage have been determined to be

as follows : Pine species other than southern pine, 5 to

8 percent; spruce including white and Engelmann, 8

percent (Holmes and Buszewicz 1958) ; loblolly and

shortleaf pine, 9 to 12 percent (Wakeley 1954) ; and

eastern redcedar, 7 percent (U.S. Forest Serv. 1948).

To maintain these moisture contents it is usually

more practical to use sealed containers than to have

the whole storage chamber kept at a low humidity. A

common type of seed container is a cylindrical can

about 36 inches tall and 18 inches in diameter fitted

with a bronze screwcap and sealed with a rubber

gasket. Such cans have an approximate capacity of

150 to 160 pounds of conifer seed. Cardboard containers of various sizes are used at the Towner Nursery.

The seed is put in a polyethylene bag and placed in the

container. A press-on lid is held in place by wire

clamps. At the Oklahoma State Nursery at Norman,

5-gallon glass bottles with screwcaps are used. Each

bottle holds 25 pounds of seed. Small lots of seed can

be kept in jars or similar containers sealed with

paraffin.

Low temperature is the other essential condition for

successful storage. Dry cold storage at 32° to 40° F.

in sealed containers is satisfactory for prolonged storage of seeds of all pines, spruces, junipers, Arizona

cypress, oriental arborvitae, and larches (U.S. Forest

Serv. 1948). Seed apparently can withstand subfreezing temperatures for several years without injury

if it is stored in sealed containers and has a moisture

content of less than 7 percent. Hence, most commercial cold-storage facilities can be used to store seed

(Rudolf 1952 ). Seed of ponderosa, loblolly, and shortleaf pines and of white spruce kept well for 4 to 7

years at subfreezing temperatures (Barton 1935).

In some of the larger Plains conifer nurseries, seed

is stored in specially constructed seed-storage facilities.

At the Towner Nursery, a 10- by 10-foot walk-in

cooler is used. Other nurseries store seed in refrigerated planting-stock storage warehouses. At the Bessey

Nursery, several large refrigeration units are used.

A few examples will illustrate the effectiveness of

dry cold storage and the magnitude of seed loss that

may occur where improper methods are used.

Ponderosa pine seed sealed in airtight containers

and held at 4P F. for 10 years maintained their

viability. One seed lot stored for 17 years and the

other for 18 years had a viability of 75 to 94 percent

(Schubert 1954). Under similar storage conditions,

Arizona cypress seed retained viabiHty for 11 to 20

years.

Oriental arborvitae seed has retained viability (95

percent) for 18 years when stored in sealed containers

and placed in refrigerators.^

Ponderosa pine seed with a moisture content of 15

percent when stored maintained their germination

after 3 years' storage in canvas bags at —4° C. (Barton

1954). Germination was reduced 20 percent during

the same period when seed with a moisture content of

17 percent was stored at —11"^.

Germination of Austrian pine seed with a moisture

content of about 8.5 percent, stored for 4 years in

sealed containers at 2° C., was 63 percent, compared

with an initial germination of 72 percent. Seed from

the same lot stored in a sack in an unheated room

showed only 1-percent germination.

The seed of white spruce with a moisture content of

6.7 percent showed an insignificant loss in germination after 7 years' storage in sealed containers at 0° and

— 18° C. When stored in sealed containers at room

temperatures, none of the seed germinated (Allen

1957).

Juniperus seed can survive even longer periods of

storage when stored dry in sealed containers at low

temperatures. The seed of Rocky Mountain juniper

stored in a cool cellar (50° to 65° F.) showed about

30 percent germination after 3/2 years (U.S. Forest

Serv. 1948). Johnsen (1959) found that seed of three

western species could survive long periods of dry storage

in bags or jars. The germination of 45-year-old Utah

juniper seed was 17 percent; 21-year-old one-seed

juniper, 54 percent; and 9-year-old alligator juniper,

16 percent.

SEED TESTING

Accurate tests of the number of seeds per pound,

purity, and germination percent are necessary if seed

is to be sown in the nursery at rates that will assure approximately the desired stand per square foot. Thm

stands waste space, allow weed growth, and mcrease

planting stock costs. Overdense seedbeds produce

undersized, spindly stock with a high cull percent and

poor survival or growth. The procedures used in seed

testing are thoroughly discussed in the "Woody-Plant

Seed Manual" (U.S. Forest Serv. 1948). New tree

seed testing recommendations of the Association of

Official Seed Analysts are expected to be available.

in 1965. . ^ Care must be taken to obtain a representative sample

^Communication with Michel Afanasiev, F^^es^ D^P^-

Oklahoma A. k M. College, Stillwater, Okla., Aprü 1958.
16 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

of seed. With a conventional grain probe, a uniform,

equal sample may be taken from the top to the bottom

of the container. Where seed lots of the same year and

origin are stored in more than one container, samples

from each container are taken and mixed. This

sample must then be subdivided until a small representative sample of 2,000 to 3,000 seeds is obtained.

A sample can be subdivided by mixing, quartermg, and

again mixing, or by using a mechanical device.

Perhaps the most reliable tests of seed viability are

those in which the seed is allowed to germinate

naturally under ideal conditions of moisture and temperature. Usually 30 to 60 days are required, so tests

are run before the spring sowing season.

In many Plains nurseries, 200 to 250 seeds of any

one lot are sown in flats that are filled with washed and

sterilized fine sand (fig. 12). The exact number of

seeds is counted and broadcast uniformly over the

sand or lined out in rows. The seed is pressed lightly

into the surface, sand is sifted over it, and the surplus

is struck off with a slat to obtain uniform depth. The

flat is then labeled with the seed collection or accession

number.

For species that germinate promptly without pretreatment, the flats are placed in a greenhouse or in

a germination room that can be lighted during the

normal daylight hours and heated to provide a diurnal

fluctuation from 68° to 86° F. (Stoeckeler and Jones

1957). The flats are watered daily. Once germination starts, the seedlings are removed every 1 to 3 days

and recorded. Ungerminated seeds remain in the

flats until germination api>ears complete, usually in

30 to 60 days.

Germination can also be tested by placing the seeds

between moist blotter paper in petri dishes. The blotters should be supported above the free water on the

bottom of the petri dish, but should be connected to it

F-488912

FIGURE 12.—Ten- by fourteen-inch flats used at the Bessey

Nursery, Halsey, Nebr., in germination tests of coniferous

seed. A mixture of half sand and half peat is bein? used

as a medium.

by strips of blotting paper. The seed should be kept

moist but not wet. Equipment should be sterilized

with heat or boiling water to reduce mold.

A Jacobson germinator " or similar device can be

used in lieu of petri dish tests (U.S. Forest Serv. 1948).

A number of constant-temperature germinators are

available. These devices greatly speed the process of

determining potential germination.

Cutting tests are commonly used by nurserymen for

a rough determination of seed quality. They are useful as emergency guides in fall sowing of freshly collected seed that have embryo dormancy, or for other

seed that have not been tested. In cutting tests, several hundred seeds are cut open with a sharp knife, and

the percentage of good seeds is determined. Good

seeds are well filled and have white or cream-colored

kernels.

Another rapid method of obtaining the germination value for dormant seed is the excised-embryo test.

The embryos are dissected from the seeds, placed on

moist, sterile cotton in petri dishes, and kept at about

70° F. for 2 to 31 days. During this period live embryos show various types and degrees of development,

such as enlargement of the cotyledons, development of

green color, and even emergence of radicle (Flemion

1941). Those that are not viable discolor and soon

deteriorate. The excised-embryo test has worked successfully on Juniperus species, ponderosa pine, and

Douglas-fir (Heit 1955). This test eliminates the effect of seedcoats and checks the condition of the embryo, where the life of the plant exists.

The most rapid viability indicator is a biochemical

method that uses tetrazolium salts. The embryos are

exposed and placed in a testing solution consisting of

0.5 gram of 2,3,5-triphenyl tetrazolium chloride in 200

cubic centimeters of water. The chemical stains living tissues a carmine red within 24 hours. Seed

viability results obtained with a test using tetrazolium

chloride compared closely with those from the excised-embryo test (On 1952). Both gave significantly

higher germination capacities for ponderosa pine and

Douglas-fir than those obtained by sand flats. The

tetrazolium (TZ) test has many inherent advantages

over other testing methods, but the accuracy of results

depends on the qualifications of the analysts who interpret it (Colbry et al. 1961). It cannot be recommended for general usage.

Facilities for testing tree seed are not available at

any of the Plains States seed-testing laboratories.

However, tree seeds used in Plains nurseries can be

tested for a fee at the Eastern Tree Seed Testing Laboratory, Macon, Ga., cooperatively maintained by the

Georgia Forestry Commission and the U.S. Forest

Service; the Oregon Seed Testing Laboratory at CorvalUs ; or the Department of Seed Investigations, New

York State Agricultural Experiment Station, Geneva.

' Mention of commercial products or specific firms does not

constitute an endorsement by the Forest Service or the U.S.

Department of Agriculture.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 17

The fees are prorated according to the total number

of tests made during the season. They have averaged

$10 to $12 per test. Tests are run for Federal, State,

and private nurseries, and for commercial seed dealers.

SEED DORMANCY AND PRETREATMENT

Seed of some conifers, including ponderosa, Austrian, Scotch, and jack pine, germinate satisfactorily

without pretreatment. Other seed, including that of

some spruces, show embryo dormancy and germinate

better if fall sown or stratified prior to spring sowing.

Germination of some seed, such as eastern redcedar

and Rocky Mountain juniper, may be delayed by the

presence of an impermeable seedcoat in addition to

embryo dormancy.

Usually dormancy can be overcome by a period of

cold, moist stratification, during which certain chemical changes occur in the seed, preparing it for prompt

germination. Pretreatment of seed frequently results

in more rapid, even, complete germination. Seed is

used more efficiently, and losses from disease are reduced. It is decidedly beneficial when seed that has

been stored for some time is to be sown. However,

stratification should not be regarded as an alternate

means of seed storage since seed has been ruined by

overlong stratification.

The seed of most pines used in Plains planting will

germinate well without stratification. Ponderosa pine

lots usually do not need stratification, but it will hasten

and improve the germination of some lots. Mirov

(1936) cites the need of pregerminative chilling in

the presence of moisture; he obtained a 7-percent increase in germination from seeds stratified for 3 months

at 40° F. Taylor (1941) obtained more rapid and

complete germination and a more even stand of seedlings from ponderosa pine seed stratified for 30 days

at 34° to 40°. He cited certain disadvantages of using

stratified seed, including poorer handling by mechanical sowers, less accurate control of sowing rates, and

injury to the seed by acid treatment of the beds after

sowing. The germination of loblolly and shortleaf

pine is much improved by cold, moist stratification for

30 days at 30° to 41° (Wakeley 1954).

White spruce, including that of Black Hills origin,

shows strong dormancy, while that for blue spruce was

moderate to nonexistent. Good germination of these

species was obtained after 50-day stratification at temperatures from 34° to 49° F. (Cram 1951).

Germination of Arizona cypress seed is usually very

low, probably because of the poor quality of seed produced commercially and possibly also because of seed

dormancy. Cold stratification in peat moss for 20 days

is recommended."^

The erratic germination of juniper seeds commonly

used in Plains planting has long been a problem in

private nurseries. Seeds of eastern redcedar have

dormant embryos which require 100 to 120 days of

^U.S. Forest Serv. Fourth Ann. Rpt., Fiscal Year 1957,

Region 8, Eastern Tree Seed Testing Laboratory.

stratification at 35° to 40° F. to afterripen (Pack 1921,

Taylor 1941). In a series of tests to determine the

most favorable temperatures for afterripening, Barton

(1951) found that 41° gave the best results, that 33°

was less efiiective, and that 50° was totally ineflPective.

Germination was arrested in afterripened seed for as

long as 3 months by storing ungerminated seed at

15° to 20° (Afanasiev 1955). Germinating seed was

injured by the subfreezing temperatures, and it did not

resume growth after storage. A reduction in germination occurs if seed is allowed to dry after stratification

and before sowing (Afanasiev and Cress 1942a).

Dormancy of the seed of Rocky Mountain juniper

is essentially the same as that of eastern redcedar except that chemical changes during afterripening are

slower and normally require 14 to 16 months after

seed maturity for free germination without pretreatment (Afanasiev and Cress 1942b). Beds of this

species have lain over without germination for I/2

years from the time of fall seeding despite depulping

and 3 months of stratification at controlled temperature. Hence, it seems best to keep this species in stratification for 6 months before seeding in the spring.

Then it usually germinates 2 to 3 weeks^after seeding.

The presence of impermeable seedcoats in a large

percentage of juniper seed will prevent complete germination. Seedcoats may be made permeable by exposure to moisture at a temperature of approximately

25° C. (77° F.) for 2 to 3 weeks. Soaking for 30

minutes in concentrated sulfuric acid is also effective ; this treatment is given before the seeds are placed

at low temperatures for breaking the dormancy of the

embryos (Barton 1951).

Scarification has been used to increase the permeability of juniper seedcoats. Mechanical scarification

of the seed in a steel drum lined with sandpaper was

used successfully at the Bessey Nursery as early as 1934

(Dayharsh 1934). A more efficient type of scarifier,

consisting of six vertical sandpaper-covered disks, was

useful for small experimental lots of seed (Stoeckeler

and Baskin 1937). For larger lots of seed, where

comparatively light scarification is needed, a modified

Ames scarifier can be used (Chapman 1936).

The methods used to induce germination of juniper

seed and the results obtained have varied depending

on location. In some places one method will produce

even, prompt germination, whereas the same procedure used elsewhere will not. The two species, eastern

redcedar and Rocky Mountain juniper, may also react

differently. The two methods commonly used are

planting the seed in the fall shortly after collection

and planting in the spring following stratification.

Consistently prompt germination of eastern redcedar

in Oklahoma has been obtained in fall sowing (Engstrom 1950, 1955). The clean, depulped, unstratn^ed

seeds are sown about December 10, covered with oneeighth to one-fourth inch of sawdust, watered, and then

covered with 0.002-gage (thickness) polyethylene film.

The film is in 1,000-yard rolls and is 53 mches wide.

Buriap is laid over the plastic film, and both are pinned
18 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

to the soil at intervals of about 4 to 6 feet with 5-inch

soil staples made of No. 9 wire.

Germination starts about March 1 and is completed

by March 10 to 15. As soon as germination starts, the

burlap and plastic film are removed from the beds,

snow fence is rolled out on the 1- by 6-inch bedboards

to provide half-shade, and the burlap is laid on top of

the half-shade for 10 days. The burlap conserves

moisture and guards against early spring freezes. In

one instance, air temperatures dropped to 12° F. without harm to the seedlings. With this method, redcedar seed completes germination about 3 weeks earlier

in the spring than does seed covered only with burlap.

Favorable results are also obtained when it is used with

Austrian and ponderosa pine.

Fall sowing of eastern redcedar is also being tried

experimentally at the Bessey Nursery. The cedar

berries are collected as soon as they are ripe and are

depulped. The seeds are dried just enough to permit

drill seeding, sown, covered with burlap, and mulched

with straw or hay. Germination has been sufficient to

produce good stands the following spring.

At the Mandan nursery of the Soil Conservation

Service, October sowing of Juniperus produced uniform germination from 1946 through 1949. Seed of

Rocky Mountain juniper was stratified at 45° to 50° F.

for a 4-month period prior to sowing, while that of

eastern redcedar was sown dry. After seeding, the

beds were mulched with a 4-inch layer of straw and

shingletow and watered until freezeup. The mulch

helped to prevent (a) winter drying when snow cover

was absent, (b) alternate freezing and thawing, and

(c) premature germination in the spring.^

SELECTION OF THE NURSERY SITE

Successful planting of conifers in the Plains begins

with the selection and development of the nursery site.

This decision is a prime factor in determining the

quality and cost of the planting stock. In fact, the

success or failure of the nursery may depend on the site

selected. Once the nursery is established, a change in

location is difficult and expensive.

The Plains have an essentially adverse environment

for growing coniferous seedlings. Common problems

are excessive alkalinity of soil or water, water shortages,

poor internal drainage and crusting and baking of some

soils, lack of mycorrhizal fungi, wind erosion, frequent

winter injury, frost heaving, hail, heat injury, much

damping-off, and damage by rodents and birds.

These are a formidable array of difficulties for those

planning to grow conifers in the Plains. All sites have

some problems. Therefore, one with the fewest

adverse factors must be chosen.

The major considerations in the selection of a nursery site are the soil and the water supply. Other

important items requiring attention are the availability

of markets, utilities, and labor; the shape, topography,

and size of tract; and the crop history of the land.

SOIL

A suitable soil in the nursery is a prime requisite

smce the characteristics of the soil influence almost

every nursery operation, from sowing the seed to shipping the stock. Soil texture, soil fertility, its reaction,

and Its alkalmity are discussed in this section. All

aspects of the management of the nursery soil are

discussed m detail in a later section.

Soils with textures that would be considered somewhat droughty for dryland farming are the ones best

adapted to conifer seedling and transplant culture.

1 he irrigation equipment, an essential feature of any

Flams nursery, will overcome a trend to droughtiness,

which IS an mherent feature of all soil profiles with

properties desired for a conifer nursery.

The surface and subsurface layers of soil to a depth

of at least 10 feet should be sands, loamy sands, or light

sandy loams. Good internal drainage is necessary,

since alkalinity problems, especially upward movement

of alkalies from evaporation, are at a minimum in such

soils. Areas with tight soils or with clay bands in the

substrates must be avoided. So too must extremely

coarse, gravelly substrates, which permit a high loss of

irrigation water.

In terms of mechanical analysis, the top 12 to 24

inches of soil should have a silt-plus-clay content between 12 and 35 percent, with subsoils preferably in the

5 to 20 percent range. Tests can readily be made with

a field test kit (Wilde and Voigt 1955) or performed

for a fee at the soil testing laboratory of the State

agricultural college.

Commercial nurserymen growing balled and burlapped stock prefer somewhat finer textured soils for

their lining-out beds, used for the second and sucœssive transplantings. Soils may be loams or even silt

loams, with a silt-plus-clay content of as much as 60

percent. Such lining-out tracts receive less watering

than seedling or "first transplant" beds; hence, the

salinity problem is not as critical.

Sandy soils have advantages over the heavy soils

for seedling and transplant culture. They have better water intake and better soil-air-moisture relationships ; they crust less, can be worked sooner after rain

or irrigation, have fewer alkali problems, and produce

more fibrous root systems (Anderson and Cheyney

1934, Howell 1932). The trees can be lifted, dug, and

transplanted with less power and less damage to the

rootlets. The disadvantages of sandy soils are their

need for more frequent watering, their lower fertility,

and their greater subjection to wind erosion.

The initial nutrient level of the proposed conifer

nursery site before fertilization, particularly for areas

devoted only to seedlings and transplants, can be somewhat lower than is desirable for farm crops. More important is the need for a friable, deep, rather porous,

slightly acid soil free from harmful alkalies. Such soik
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS in

are likely to be deficient in available phosphorus. surface from 6.5 to 7.5, and seedlings of sensitive

They may also contain less total nitrogen and organic species began to show the effects. Stunting patchmatter than is necessary for conifer production. But iness, poor stands, and a low percentage of plantable

these deficiencies can be remedied by means described trees were observed in some beds. The condition was

in the section on "Soil Management." readily corrected with acidifying materials.

The pH of the prospective nursery site is quite likely Water drawn from wells may be somewhat less

to be 6.0 to 7.2 for soils that have not been irrigated. alkaline than surface water taken from streams and

Use of soils with a pH of 7.5 or higher, especially it is also free of weed seed. Moreover, salinity of water

those of fine texture, is almost certain to result in in- in some streams tends to increase as the river stage

soluble or very costly problems of pH adjustment, due drops; at this time water needs in the nursery may be

to an excess of carbonates and alkalies. (See Eng- quite high.

Strom and Stoeckeler 1941 and Richards et al. 1954 The irrigation water required depends on the size

for more discussion of this problem.) However, for of the nursery, its latitude, relative acreage of seednursery blocks that produce balled and burlapped stock beds and transplants, amount and distribution of rainfrom transplanted seedlings, satisfactory growth has fall during the growing season, method of irrigation,

been obtained in soils with a surface pH as high as stand density, protection by windbreaks, and amount

7.8, such as in the High Plains of northern Texas near of shade on seedbeds. Nurseries in the Southern

Lubbock, where oriental arborvitae, various junipers, Plains often need more water than those in the Northand some of the drought-hardy pines are being ern Plains. Nurseries in the Western Plains require

produced. more irrigation water than those farther east, where

Use of soils with more than 500 p.p.m. (parts per the rainfall is higher. Flood or furrow irrigation remillion) of total soluble salts has created difiBculties quires more water than sprinkler irrigation. More

in the growing of pines and spruces, owing to chlo- water will be needed in abnormally hot seasons such

rosis, excessive damping-ofif, crusting of salts on the as occurred in 1936.

surface due to evaporation of irrigation water, and During years of normal precipitation the total irphosphate and other nutritional unbalance. rigation water needed for nurseries growing both

seedlings and transplants is estimated to be as follows:

WATER SUPPLY

Annual supplemental

Most States have laws on water use, particularly . .• ^^^7- ^V^\

. . f. r 1 ^ 1 ¿vocation [incnes)

on the pumpmg of water from lakes, streams, and Northern Plains 10-15

reservoirs. Some States require registration of pumps Central Plains I 15-25

drawing irrigation water from wells. The State Geo- Southern Plains 25-30

logist can provide information. _ ^ ^ . . i i c o • i

Experience has shown that irrigation water for use ^^ years of abnormal heat or drought 5 to 8 inches

. -n • • -ni • -r • 1. u T_ I .U must be added to the above amounts. Most nursery- in Frairie-Plams conifer nurseries should have less than -n r , u ^ ^ -^u «^-i OAA r 1 1. 1 1 T 1 /T. 1 rnen will prefer to have a water system with a capacity

200 p.p.m. of total dissolved solids (Engstrom and sufficient to water the necessary area in daylight hours,

Stoeckeler 1941). For sensitive crops, as defined by ^^¿ ^ ^^^pl^^ capacity for watering on a round-thethe Salinity Laboratory at Riverside, Calif., the sodium ^i^^k basis in seasons of drought or extreme heat. A

adsorption ratio of the irrigation water should be under AQ^ of 450 gallons per minute is equivalent to 1 acre10 and the boron content less than 0.5 p.p.m. (Rich- inch of water per hour.

ards et al. 1954). Most conifers grown in the Prairie- For nursery blocks devoted to balled and burlapped

Plains are in the sensitive-crop category, so these stock spaced in rows 40 to 80 inches apart, a capacity

criteria should be considered approximate permissible of 10 to 20 gallons per minute per acre is aniple.

maximums. In nurseries devoted to the growth of For sprinkler irrigation, per-minute capacities of 50

balled and buriapped stock, where the water need is and 30 gallons of water per acre of seedbeds and transless than for seedbeds or transplants, water with as plants, respectively, are sufficient. Extensive use ot

much as 400 to 500 p.p.m. of dissolved solids has been Aood irrigation will require 30 percent more water.

used. Higher amounts may be permissible with proper AVAILABILITY OF MARKETS, UTILITIES,

periodic soil treatments, such as acidification. AND LABOR

Even though irrigation water meets the above speci- r u 1 u

fications, alkalinity problems can still occur. Con- The nursery site should be close to or slightly south

tinued irrigation for several years may result in an and east of, the market center of the area to whicn

unsatisfactory condition in the soil surface. An stock is to be shipped. The warmer climate to me

example is the water supply at the Towner Nursery, south permits lifting of the stock when the planting

Towner, N. Dak. Analysis at the time of nursery season opens. If other factors are equal, the more

establishment showed 187 p.p.m. of total dissolved easteriy locations have the advantage ot greater

solids in the irrigation water. Two years of heavy rainfall. 1 1 1 u A fn

watering raised the average reaction (pH) of the soil The nursery location should have good access to
20 AGRICULTURE HANDBOOK 2 79, U.S. DEFT. OF AGRICULTURE

railroad, highway, telephone, and telegraph facilities^

The type of planting stock distribution anticipated

naturally has a bearing on transportation needs. However, since deficiencies cannot be remedied easily, adequate service at the start is virtually essential The

nursery must be on an all-weather road. Electric

power is almost a necessity for light, seed and planting stock refrigerators, and other miscellaneous needs.

There must be an adequate supply of labor near

the nursery site. The amount of labor needed varies

widely, depending on the size of the nursery, the extent of mechanization, the degree of chemical weed

control, and the amount and kind of stock grown. For

about 6 weeks in the early spring, when labor needs

are at a peak, about 2.0 laborers are required per acre

of nursery seedbed and 1.5 laborers per acre of transplants. For 2/2 months in late spring and early summer, the average requirements may be about 1.5 laborers per acre. And for about 3 months in late summer and fall, the requirements are 0.75 laborer per

acre. The average required for this 7-month period

is about 1.3 laborers per acre. Women and girls may

constitute as much as 30 to 50 percent of the labor

force and often do most of the transplanting, grading,

and counting of stock.

SHAPE, TOPOGRAPHY, AND SIZE OF TRACT

Ideally the nursery tract should be square or

rectangular; the long dimension should not be more

than twice the short one. However, the best site

available may be a long, narrow tract. An efficient

layout is more difficult to obtain on such a piece of

land, but the disadvantages can be minimized by careful planning.

A level tract with stone-free, deep loamy sand or

light sandy loam soil is desirable. Such sites are most

often on a stream terrace or glacial lake bottom. If

furrow irrigation is anticipated, the land should have a

gentle slope in one direction, preferably 0.1 to 0.2

percent on fine sandy loams, and slightly more for

loamy fine sands. On very sandy soils, which absorb

water rapidly, slopes up to 0.5 or 1.0 percent have been

successfully irrigated in furrows. On land with more

slope, it may be necessary to lay out the beds on contours with terraces.

Existing wind protection can often be used in choosing a nursery site. Natural or planted trees or situations favored by local topography may reduce the need

for, or time required to obtain, adequate protection.

The tract must be large enough to meet immediate

and preferably long-range production goals. Space

calculations also must consider the need for cover

and soil improvement crops in the rotation.

To compute nursery acreage needs per million trees

for any specific age class, the probable production of

usable trees per square foot of seed and transplant

beds must be known. An average of 40 usable seedlings

or 5 usable transplants per square foot of bed is a

reasonable assumption for Prairie-Plains conditions.

On this basis the net space requirements per million

trees produced will approximate those in table 4.

Other seedling and transplant densities niay be used

similarly in determining net space requirements of

individual nurseries. For example, where seedlings

are field planted directly, an average need of 30 trees

per square foot might be assumed.

TABLE 4.—Net space requirements per million trees

of seedlings and transplants, excluding paths and

roads '^

Acres required for—

Age class of

stock 1st

year

2d

year

3d

year

4th

year

5th

year

Total

1-0 0.57

.57

.57

.57

.57

.57

.57

.57

.57

0.57

9-0 0.57

.57

4.59

.57

4.59

.57

.57

.57

1.14

'\-C\ 0.57 1.71

1 1 5.16

9 1 4.59

4.59

4.59

.57

4.59

5.73

1 2

9.75

2-2 4.59

4.59

4.59

4. 59

4.59

10.32

3-2 10.89

2-3 14.91

1 Figures are based on 40 plantable seedlings and 5 plantable

transplants per square foot.

The gross producing area of the nursery should be

three to four times the net space requirements. An

area of this size allows for paths, roads, and other nonproduction areas, and for cover crops in the rotation.

Additional space must be allowed for windbreaks.

The minimum size for nurseries producing several

million seedlings and several million transplants is 20

to 40 acres in actual tree production, with 10 to 20 additional acres in reserve or cover crop.

CROP HISTORY OF I.AND

The class of land most likely to be selected for a

conifer nursery site is former farmland. Such land is

usually free or nearly free of the more serious noxious

weeds such as quackgrass and field bindweed. Areas

that have been in intertilled crops are more amenable

to immediate sowing of seedbeds than are those

formerly in small grain or hay crops. The weed problem in the latter areas is likely to be serious for several

years.

There may be tracts of grassland, pasture, or wild

hayland suitable for nursery development. These

generally would not be suitable for tree production for

about 2 years after breaker plovdng. They should

preferably be summer fallowed for 1 year and planted

to an intertilled agricultural crop the second season.

Only then is the soil likely to be in good enough condition for nursery production.

More rarely, abandoned agricultural land with

suitable topography and reasonably adequate fertility,
CONIFER NURSERY PRACTICE EST THE PRAIRIE-PLAINS 21

but with a somewhat droughty nature, may be used.

It may have been abandoned because of its droughtiness. However, if other factors are favorable, if the

area has good internal drainage, adequate topsoil

depth, proper soil texture, and an adequate supply of

water of the desired chemical properties, it may be

considered a potential nursery site. But the weed

problem would probably be so serious as to require 2

years of development by the method described for

grassland.

DEVELOPMENT OF THE NURSERY SITE

After the nursery site has been selected, it must be

developed. Physical data on soil and ground relief

characteristics must be obtained during or immediately

after acquisition for use in planning the development.

Careful groundwork will lessen the need for costly

future alterations.

An accurate map with a scale of 1 inch to 50 to 100

feet should be made. On this map the layout of the

water system, roads, windbreaks, and buildings can

be diagrammed. A topographic map with a contour

interval of 0.5 to 1.0 foot is useful in leveling and

other necessary ground fitting. If flood irrigation is

planned, such a map can be used to determine the

location of the main ditches or flumes and grassed

waterways. It also can provide the basis for subdividing the nursery.

SUBDIVIDING THE NURSERY

The site selected for a nursery is usually smooth, but

there are always some small humps and minor depressions that need to be leveled. Where the cut or

fill is more than 3 or 4 inches, it is desirable to stockpile

the topsoil, perform the leveling, and replace a normal

cap of topsoil on the disturbed area (Mony 1935).

Trash, straw piles, scrap lumber from old buildings,

and other debris should not be burned on any area to

be devoted to the growing of trees. Experience has

shown that trees grown on the burned areas are more

subject to damping-off", and growth is depressed, at

least on the first crop.

On land with more than a 1 -percent slope, the nursery should be subdivided on the contour. The degree

of slope and the type of irrigation to be used determine

the specific pattern. A system of broad-base terraces

should be developed at intervals of 100 to 150 feet.

The vertical interval may be 1 to 3 feet. At Norman,

Okla., hedge windbreaks were established on the

downhill side of each terrace. At most nurseries, slatwire snow fences are preferred, since they occupy less

space, can be readily moved, and harbor no disease or

insect pests as living hedges sometimes do.

Terraces in areas where rather high-intensity rains

occur should have some grade. Those at the State

Nursery at Norman, Okla., have a grade of about 1

percent, with a vertical interval of 2 feet between

terraces. The Spacing of terraces, both horizontally

and vertically, and their rate of fall depend on the

infiltration rate of the soil, steepness of slope, crop,

length of terrace, and facilities for disposal of runoff

water.

Agricultural engineers have worked out detailed

guidelines on the development of terraces, and numerous publications with data of local or regional application are available. The technicians of the Soil Conservation Service have helped many nursery personnel

lay out a system of terraces and grassed waterways.

On level land, the irrigation system to be used is

the chief factor in subdividing the nursery. A common basic subdivision is rectangular, 400 to 500 feet

long and 250 to 500 feet wide. A subdivision of this

size will accommodate the standard overhead irrigation system. Where portable surface-pipe irrigation

with rotary sprinklers is to be used, distances from the

riser to the end of the line may be 700 to 900 feet.

DEVELOPING THE IRRIGATION SYSTEM

The type of water supply that should be developed

depends on the volume required for irrigation. The

choice is often dictated by the quantity and quality of

the water available on the nursery site.

The nurseryman must determine the best method of

pumping and distributing the water. The type of

pump and motive power to be used will depend on

the quantity needed, the pressure desired, and the

depth of the water table.

However, most nurseries in the Plains depend upon

wells as a source of water. Deep wells cost more to

develop and pump than shallow wells, except possibly

where artesian pressure is available.

A few nurseries pump from streams and ponds.

Open water sources are usually less costly to develop

than wells. Several wells and pumps are better than

a single one, which may break down or fail occasionally. Where multiple installations are made, they

should be far enough apart to avoid overlap of their

cones of depression under sustained pumping.

Well points may be adequate for small nurseries but

are not recommended where a large quantity of water

is required. Because of the frequent fluctuations in

the depth of the water table due to long droughts and

the heavy drain upon the underground water supply,

it is difficult to maintain a satisfactory water level in

the ordinary shallow well or battery of well points.

However, this difficulty can be overcome by increasing

the depth of the well as the water table drops or by

constructing a deep well equipped with a turbine

pump.

Most nurseries use deep-well turbine pumps to obtain their water supply. These should be installed on

a contract basis, with a guarantee of development of
22 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTUBE

a specific minimum amount of water per unit of time

under sustained pumping of 8 or more hours.

Centrifugal pumps are satisfactory where water is

pumped out of streams or shallow water tables. The

suction lift should not be more than 15 feet, and 5 to

10 feet is preferred. Shallow wells are often cased

with perforated steel pipe, and coarse sand and gravel

are placed next to the intake to accelerate inflow of

water and to reduce the rate of clogging of the screen

with finer sand particles. Details of casing a well

are given in Agricultural Handbook 110 (Stoeckeler and Jones 1957) and in numerous State college

publications on irrigation and well development

(Duffin 1955, Fischbach et al. 1957).

There are three general types of irrigation; use is

made of (1) overhead pipelines, (2) sprinklers with

a portable surface pipe, and (3) furrows or flooding.

The overhead system is the type most widely used

nationally in coniferous nurseries. It is usually the

standard against which other systems are compared.

The overhead system, which is convenient and simple to operate, consists of a series of parallel pipes

spaced 52 to 53 feet apart and resting on pipe supports

at 12-foot intervals (fig. 13). Nozzles are spaced at

2- or 3-foot intervals on the pipe. When this system

is in operation, oscillators driven by the water pressure

turn the 200- to 500-foot lengths of pipe through an

arc sufficient to water a strip about 28 feet wide on

each side of the pipe.

Water is distributed efficiently, and maintenance

costs are relatively low. The primary disadvantages

are the high initial cost and rather incomplete coverage obtained when winds are blowing. Both the

underground and overhead piping must be carefully

planned and installed to assure top performance.

F-325967

FiGxiRE 13.—Installation of the 1936 expansion of the

Towner Nursery water system. Note mains and risers,

cross trenches across future roadway at left for risers to

be installed m opposite side, and the long, parallel overhead Imes shortly to be placed in the pipe supports.

FIGURE 15.—A portable sprinkler irrigation system at the

Oakes Nursery, Oakes, N. Dak. The pipe is of 4-inch

diameter and is in 20-foot lengths, and the sprinklers are

40 feet apart. One well supplies 13 sprinklers; each

throws 13 gallons per minute. There are three wells on

the 40-acre tract. Note the excellent wind protection afforded by the dense one-row planting of Siberian elm, 25

feet high 20 years after planting.

The surface-pipe sprinkler system consists of an underground water main to which lightweight, quickcouphng metal pipes are attached (fig. 14). Each

section of pipe is 20 to 40 feet long, and rotating singleor double-nozzle sprinklers are installed at 40-foot intervals (fig. 15). Lengths of 600 to 700 feet may extend

from the underground water mains.

The nozzle sizes used in the rotating type of sprinkler

should generally be one-eighth or three-sixteenths inch

in diameter, especially for first-year seedbeds; nozzles

of larger diameter throw so much water that there is

much undesirable splash and soil movement in the

beds. For second-year seedbeds and for transplants,

larger nozzles would be peimissible since soil splash

is not as serious a problem, even with nozzle sizes putting out as much as one-half inch of water per hour.

The usual capacity of sprinkler heads used in conifer

nurseries is 9 to 18 gallons per minute.

The initial cost of the surface-pipe sprinkler system is less than that of the overhead system. This

method is more flexible and therefore better adapted

to the smaller nursery. But it is less convenient. Distribution of water is not as uniform. Splashing and

soil movements are likely to be greater problems.

More details on sprinkler watering, estimates of

water needs, and other aspects of irrigation are available in publications by Fogel ( 1957), Monson ( 1952),

Monson et al. (1953), Thorfinnson et al. (1955),

Wiersma (1955, 1956), and Woodward and Gilden

(1955).

Flood or furrow irrigation should only be used as

a supplement for the sprinkler systems in conifer nurseries. The porous soils required for best conifer production cause uneven distribution of water, excessive
CONIFER NURSERY PRACTICE m THE PRAIRIE-PLAINS

23

STATE NURSERY

NORMAN, OKLA.

SCALE

P 5.45 AC.

PROPOSED EXTENSIONr:;SÄS3

H 5.22 AC.

FIGURE 14.—Sprinkler irrigation system layout used at the Oklahoma State Nursery at Norman.

Surface pipes of 4-inch diameter are laid on the contour between terraces from hydrants.

The main pipeline is 8 inches in diameter.
24 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

water use, and leaching of soil nutrients. Also, flood

irrigation is less apt to produce the fine fibrous root

system desired on pines. _ .

Under some circumstances, flood or furrow irngation may be a convenient means of watering transplant beds or second-year seedbeds. Straight rows

are preferred to contour rows because of the greater

ease of layout.

SEEDBED PREPARATION AN» SOWING

Ordinary farm equipment—tractors, plows, disks,

and harrows—is used to prepare the soil for seedbeds,

transplant beds, or cover crops. The choice of equipment will depend on the size of the nursery, comparative costs, and the personal preference of the nurseryman.

Both wheel and crawler-type tractors are used in

Plains nurseries. The heavy jobs in the larger nursery

will require a tractor of about 35-drawbar horsepower.

A fight unit of 15 to 18 hp. is suitable for the lighter

jobs or as the basic power unit for the small nursery.

Tractors equipped to use two- or three-point suspension implements are more maneuverable and versatile.

Rotary tillers are used at a few Prairie-Plains nurseries for ground preparation. They do an excellent

job of incorporating manure, peat, and compost into

the soil. However, they tend to pulverize the soil too

finely, leaving it more subject to wind erosion.

As part of soil preparation, small patches of weed

pests such as quackgrass can be spaded out carefully by

hand, or eliminated by repeated use of a potato digger,

quacker, or rotary tiller (Clifford 1934). If a rotary

tiller is used, the hinged rear cover is folded so as to

throw soil and roots a maximum distance. After use

of any of the three machines, the roots are raked and

picked off the surface. Especially heavy patches of

quackgrass or other noxious weeds can be eliminated

by use of chemicals such as methyl bromide, ammonium trichloracetate, or sodium trichloracetate. The

manufacturers' instructions should be followed carefully. Sources of information on nursery machinery,

equipment, and chemicals are given in the Appendix.

STAKING OUT AND PREPARING THE BEDS

After the seedbed area has been worked down and

leveled, 4-foot-wide beds are staked out. Where overhead irrigation is to be used, 10 beds usually are spaced

between the pipefines. The space next to the pipeline

is usually 18 inches wide, and the nine paths between

the 10 beds are 12 inches wide. Some nurseries use

only nine beds in order to allow more path width.

Stakes are set at each end of the bed, and binder twine

is stretched between them to maintain alinement.

The final fitting of seedbeds is done by one of several

methods. The object is to secure a smooth, slightly

crowned, or flat bed. The paths are usually made a

few inches lower than the bed centers. Mechanized

equipment has superseded hand methods, reducing

manpower requirements per unit of land prepared for

seeding. A commercial seedbed shaper (Story 1940),

or some adaptation of it (fig. 16), is used at the larger

nurseries.

A method suitable for small-scale operations involves

the placement along each bed of two 1- by 4-inch bedboards spaced 44 inches apart inside. The bedboards

are held down with inverted U-shaped strap iron stakes

(Robbins 1935, Stoeckeler and Jones 1957). The bedboards serve as a track on which to slide the bed leveler

(fig. 17a). The simple device consists of a piece of

1- by 8-inch board 43 inches long; a piece of 2- by 4-

inch wood about 2 feet longer than the 1- by 4-inch

leveling blade is placed on both sides of the board. To

reduce wear on the leveler, a steelplate is placed on

the bottom of the leveler where it rides on the 1- by

4-inch bedboard. Once beds have been sown, dry,

sandy nursery soil is sifted over them, and they are

again leveled, with an adjustment for varying the

depth of seed covering.

Seedbeds may also be prepared with a smoother^

F-504414

FIGURE 16.—A tractor-mounted bed shai}er which forms and

levels a seedbed in one operation. Bessey Nursery, Halsey, Nebr.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 25

F-475099, 505893

FIGURE 17.—Two methods of seedbed preparation: A, a

simple and effective float suitable for use on 1- by 4-inch

bedboards; B, a seedbed smoother in operation.

(Futrell 1959) or a 4-foot-wide drag (fig. 17b). Drill

seeding is done directly on this prepared bed.

In all bed preparation some hand touchup of the

beds is necessary. The surface of small spots which

has become excessively smooth or "shiny" is sHghtly

roughened with push brooms or springy-tined leaf

rakes just before seeding so that light seed will remain

in place after broadcasting and before the seed covering is applied.

In some nurseries rollers are used to firm the seedbeds prior to sowing; other nurseries depend on the

walking done on the beds while they are being

smoothed, raked, or leveled. Rollers are also used to

press the seed lightly into the soil after the beds

nave been seeded and covered. In large nurseries

where seeding has been mechanized into one operation

in which only one machine is used, the roller has been

made an integral part of the seed drill.

COMPUTING THE AMOUNT OF SEED

TO SOW

Seed should be sown on the basis of a specific weight

of seed per unit of area to secure desired seedbed densities and to prevent seed wastage. Laboratory tests

should be used to determine the germination percent.

For freshly collected seed such as juniper, which may

have to be fall-sown in the same season it is collected

a cutting test should be used to provide an estimate

of quality.

The amount of seed to sow can be estimated by the

following formula :

P= AxD

GxSxY

where P = pounds of seed;

.4 = area in square feet;

£> = desired density in number of seedlings per

square foot;

G = germination percentage of the seed, expressed as a decimal;

S = number of seeds per pound at time of seeding; and

Y = survival factor expressed as a decimal.

The survival factor (Y) is the percentage of the

viable seed that survives to the transplantable seedling

stage, whether that be the 1-0, 2-0, or 3-0 age. It

varies greatly by species and nursery and drop« with

increasing age of the seedling (table 5). The survival

factor can be determined only after data are obtained

from germination tests, cutting tests, sowing rate tests,

and bed inventories.

Seedbed density has a marked effect on stock quality,

seedling size, cull percent, and efficient use of seed.

It can be varied so that the maximum number of trees

suitable for transplanting or direct field planting are

produced. The experience and judgment of many

nurserymen indicate that pine and juniper seedlings

to be transplanted should be grown in broadcast-sown

beds at a density of 50 trees per square foot, and that

spruce intended for transplanting (2-0 and 3-0)

should be grown at densities of not more than 100

trees per square foot. For drilled spruce seed the

density can be reduced to 60 to 75 trees per square foot.

In some of the Southern Plains States, conifers shipped

from the nursery are fieldplanted as seedling stock,

usually as 2-0. Such trees are grown at a density of

30 per square foot.

Fifty years ago Pearson (1914) recommended seedbed densities for ponderosa pine of about 75 per square

foot. Higgins ( 1928) evaluated the seedbed density of

ponderosa pine in terms of the lowest cost per surviving

2-1 tree in the field. He favored a seedbed density of

75 trees or less per square foot (table 6). Wahlenberg

( 1929) studied ponderosa pine under a range of densities from 80 to 275 trees per square foot and found 80

to be best. The stem diameter decreased 0.1 millimeter for each 44-tree increase per square foot. After
26 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

TABLE b.—Survival ratios for several species^ and age

classes of stock at two Plains nurseries

Species

Towner Nursery Mandan Nursçry ^

1-0 2-0 1-0 2-0

Blue SDruce 0.43

.73

.70

.57

0.39

.63

.62

.45

0.50

.68

.53

0.30

Ponderosa pine

Rocky Mountain

luniDer

.60

.50

1 Formerly operated by the Soil Conservation Service.

2 years in the field, the stock planted as 2-0 had a

1-percent decrease in field survival for every 15-tree

increase in seedbed density. Current practice is to sow

for 50 pine trees per square foot.

The number of 1-0 seedlings that survive in relation

to the number of seeds that germinate also is influenced

by seedbed density. Higher tree survival factors are

obtained when medium-to-low seeding densities are

used. In an experiment at Towner, N. Dak., with

ponderosa pine, a medium seeding density of 112 seeds

per square foot resulted in a 66-percent survival of 1-0

seedlings (fig. 18).

TABLE 6.—Nursery performance, and second-year

field survival and cost of 2-1 ponderosa pine as

affected by nursery seedbed densities

Trees per Survival Second- Final

square Average Nursery in trans- year field cost of

foot of weight cull plant survival of 1,000

seedbed per tree bed trans- surVIvmg

(number) plants trees

Grams Percent Percent Percent Dollars

76 3.98 5.4 89 75 4.48

95 3.88 7.5 88 67 5.05

121 2.88 9.4 88 62 5.52

141 2.60 11.1 85 61 5.62

TIME OF SEEDING

The time of year to seed conifers depends on the tree

species, growth rate, and, to some extent, nursery

location.

Seed dormancy and optimum germination temperature vary by species. Species having seed with embryo

dormancy or a combination of embryo dormancy and

impermeable seedcoat are fall sown, or they may be

spring sown if the seed is first subjected to cold stratification. Those with impermeable seedcoats but no

embryo dormancy are preferably spring sown after the

prescribed pretreatment for rendering the seedcoat

permeable.

70

> UJ

(L ^

UJ

o

ce <

60

o\ if) O

a: I

D -

Z

55

50 100 150 200

VIABLE SEED SOWN PER

SQUARE FOOT (NUMBER)

FIGURE 18.—Relation of first-year survival percent in ponderosa pine seedbeds to amount of viable seed sovm per

square foot. Towner Nursery, Towner, N. Dak.

Because of the longer growing season available to

them, fall-sown seedlings commonly are larger and

better developed at the end of the first season than are

spring-sown seedlings. This diflFerential growth of

fall- and spring-sown beds can be used to produce seedlings of the desired size for field planting or for transplanting.

Local climate must also be considered in setting the

time of seeding, particularly for fall sowing. Premature germination, with subsequent freezing and

mortality of seedlings, can be avoided by delaying seeding to a time when unseasonable warm temperatures

are less apt to occur. Coverings v/ith insulating qualities, such as clean straw or marsh hay, can be applied

to fall- and spring-sown beds to delay germination in

the spring. With the above reservation, spring seeding

should be done as early as the ground can be worked

to allow the seedlings the maximum growing period.

Emergency late-season seeding (early summer) subjects the seedlings to high air and ground temperatures

during germination and early growth, and frequently

results in high mortality.

Eastern redcedar is sovm in the fall after pretreatment. Seed of the current year depulped and cleaned

with a lye solution usually germinates promptly the

following spring. Rocky Mountain juniper is handled

similarly but with less consistent results.

Most pine seed is sown in the spring. This is the

general practice for ponderosa pine throughout the

Plains. Promptly germinating species, such as jack,

Scotch, shortleaf, Japanese red, and Japanese black

pines, are also spring sown. Sometimes, to even out

the nursery workload, ponderosa pines and other pines

are fall sown. White pines, such as limber pine or

Swiss stone pine, should be sown in the fall; if stratified

seed is used, they should be sown in the spring.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 27

Ponderosa pine in some Dakota nurseries is too small

for transplanting as 1-0 and somewhat too large as

2-0. By delaying the seeding to about the first half

of June, a 1 /2-O tree about the right size for transplanting is produced. Such summer seedings must be

watched carefully to avoid heat injury to the tender

seedlings in midsummer. They may require not only

shading but also more frequent light sprinklings to

reduce soil surface temperatures. Summer seedings of

ponderosa pine have also been used at the Bessey

Nursery.

Spruce seed of dormant lots should be sown in the

fall. However, if the seed are nondormant or stratified, they may be sown in the spring. In North

Dakota ° and Wisconsin (Jones 1934), white spruce

seed sown in the fall germinates more promptly and

completely than that sown in the spring.

BROADCAST VERSUS DRILL SOWING

Drill sowing has generally replaced broadcast seeding by hand in Plains nurseries, since it is more economical. It eliminates the cost of sand covering and

permits mechanical cultivation.

However, broadcast seeding results in a more uniform distribution of seed, better mutual protection of

seedlings, quicker formation of a complete ground

cover, and more rapid suppression of weeds (Arnold

1956, Meines 1939). Brewster and Larsen (1925)

found a 20-percent higher stand in broadcast beds

than in drill-sown beds of ponderosa pine, both sown

with equal amounts of seed.

At the Towner Nursery, in a controlled experiment,

no significant difference was found between the two

seeding methods in ponderosa pine beds grown at an

average density of 59 trees per square foot. The average tree percent, based on viable seed sown, was 95.1

for drill-sown beds and 86.4 for broadcast-sown beds.

At the 2-0 stage it was 66.2 and 65.6, respectively; the

average fresh weight of 30 trees was 24.3 and 26.3

grams, respectively. All drill sowing was done by hand

at carefully regulated seeding depths (fig. 19).

Spruces generally are regarded as better suited to

the broadcast-sown beds than the usual drill sowings,

since the depth of cover can be controlled more closely

for broadcast seed. However, the best of the machine

drill sowing should approach the control obtained by

the hand method.

Research has shown no clear-cut advantage for

either method in the quality and quantity of seedling

stands produced, and the choice by the nurseryman

will doubtless be influenced more by other considerations, such as the area of seedbed to be sown and

equipment available for seeding.

SEEDING EQUIPMENT

Seeding, except on small-scale operations, is done

with mechanical seeders which place the seed in rows

' Personal communication with John Molberg, Associate

State Forester, Bottineau, N. Dak.

FIGURE 19.—Two- by four-foot experimental beds after use

of hand method of drill seeding. The drills were made

by tamping the 10-cleat frame in the background into a

level, newly prepared, loose, moderately moist bed. The

cleats are three-fourths by 1 inch. Seed is covered by

hand or with the back of a rake drawn parallel to the

drills.

or broadcast over the seedbed. Some seeders are manufactured commercially (fig. 20, A and C), while

others may be built in a nursery shop from individual

grain drill units assembled in batteries of 7 to 10 drills O

per 4-foot-wide bed (fig. 20ß).

A lawn seeder is sometimes used. It is simply a

V-shaped trough with adjustable openings in the bottom, which feed out the seed at a specific rate. A

shaft rotor in the bottom is turned by the forward

motion of the seeder and keeps the seed stirred up and

feeding properly. The seed is covered by a mechanical Sander. The seeder broadcasts seed over a full

4-foot-wide bed, and can successfully handle seed as

small as white spruce (200,000 per pound) and seed

sown to obtain 75 trees per square foot." This seeder

is especially suitable to small nurseries with a production of a few hundred thousand trees or less per year.

A second type of seeder, one with a 10-spout seeder,

can be used for drill seeding (if equipped with 10 mdividual drill openers and closers), or can be adapted

to broadcast seeding by letting the seed drop on a

baffleboard placed at approximately a 45-degree angle

to make the seeds bounce and slide toward the back,

as the seeder is pulled forward (fig. 20B). It may be

hand drawn or pulled by tractor. The seeder may run

"Personal communication with Robert Heintz, fonneriy

Nursery Superintendent, North Dakota State Nursery,

Towner, N. Dak.
28 AGRICULTURE HANDBOOK 279, U.S. DEPT. OF AGRICULTURE

on wooden tracks or on the smoothed soil of the seedbed path.

Seeders that sow and cover the seed in one operation are more commonly used than the preceding types.

These sow the seed in drills the length of the bed.

One or two flat rollers are incorporated (fig. 20C) ;

these perform the final smoothing and firming of the

seedbed and drive the seeding apparatus. The seed

is fed from a common hopper through modified grainseeding tubes to the seeding assemblies. Each assembly consists of an adjustable furrow-opening shoe and

a furrow coverer. Packing wheels firm the soil in each

drill row, before and after seeding.

On another type of seeder, two corrugated rollers

are mounted rigidly in tandem, with one slightly offset

from the other. The seed is fed into the sharply defined furrows formed by the first roller. It is then

covered by the action of the second roller, which splits

the ridges formed by the first roller.

All seeders can and must be adjusted to put out a

specific number of seeds per square or lineal foot of

drill. The usual procedure is to lay down a large

F-505890, 296336

FIGURE 20.—Several types of seeding machines suitable for

4-foot-wide conifer beds: A, A seeder used in combination with a roller; B, modified grain drill with 10 tubes,

here used for broadcast seeding; C, eight-drill seederroller combination, Big Sioux Conifer Nursery, Watertown, S. Dak. C, (Courtesy of S. Dak. Dept. of Game,

Fish, and Parks. )

canvas and, after making an approximate adjustment,

to draw the seeder over it for a specific distance; the

amount of seed laid down per unit of area is then

counted and weighed. Adjustments are made until,

after a few trials, the right amount of seed is laid down.

The seeder is then ready to sow that specific lot of

seed. Frequent checking is needed as seeding proceeds

to make sure that each drill is feeding, that no refuse

is clogging the feeding mechanism, and that the seed

hopper or hoppers have enough seed to maintam a

uniform flow.

COVERING THE SEE»

After the seed is sown, a uniform depth of covering

is needed for even germination of seed and a uniform

stand of seedlings. Deep sowing makes emergence

more difficult and increases the possibihty of injury

from damping-ofï fungi.

The proper sowing depth depends upon seed size,

soil texture, and the season of sowing. The common

practice is to sow the seed of the larger seeded species

such as ponderosa pine at a depth of one-fourth to

one-half inch and that of the finer seeded species at

one-eighth to three-sixteenths inch. The seeding

depth can be about one-third greater in the light

sandy soils than in the heavier loam soils because of

the greater ease of seedling emergence in the sandy

soils. Seeds should be sovm slightly deeper in the fall

than in the spring to insure adequate covering of the

seed in beds exposed to frost action and wind erosion.

The sowing depth recommended for ponderosa pine

is supported by research. Show (1917) found that
CONIFER ISTÜRSERY PRACTICE IN THE PRAIRIE-PLAINS 29

one-half inch cover was quite satisfactory. Brewster

and Larsen (1925) found that on comparable plots

under northern Rocky Mountain conditions, the number of seedlings obtained according to cover depth was

as follows: one-fourth inch, 680; three-eighths inch,

650; one-half inch, 600; three-fourths inch, 550; and 1

inch, 470.

Trials at the Towner Nursery in North Dakota, in

a considerably drier area than mentioned by the above

investigators, showed the germination of ponderosa

pine to be dependent both on depth of seeding and

whether burlap mulch was used (fig. 21 ). Two seed

lots of different germinative energy were used. The

best stands with both seed collections were obtained

with one-fourth to five-eighths inch depth and a burlap

mulch. At three-fourths inch and deeper, the stand

count for seed with a burlap mulch dropped very

rapidly. Apparently under burlap, surface drying

of beds is not as severe as in unmulched beds, and a

very thin soil or sand cover suffices. However, when

no burlap mulch was used, one-fourth inch proved too

shallow a cover, and the unmulched seed in a considerable range of sand depth (three-eighths to threefourths inch) gave better stands.

Managers of Prairie-Plains nurseries on sandy soils

generally use drill seeding and thus avoid the need to

cover the seed in a separate operation. However, in

nurseries located on heavier soils there are excellent

DEPTH OF SAND COVERING IN INCHES

FIGURE 21.—The effect of depth of covering and use of

burlap mulch on the germination of ponderosa pine seed,

Towner Nursery^" Towner, N. Dak. Two seed collection

lots were used; the numbers on the trend lines designate

these lots.

1748-005 0—65 3

reasons for using broadcast seeding with peat, sand,

or sawdust as a seed covering to avoid crusting. ' Straw

mulches have been used in some nurseries, but onefourth inch of sawdust was reported to be more effective (CliflFord 1955, Knight 1958) ; it has the advantages of bemg free of weed seeds and not requiring removal (Allison and Anderson 1951 ). Whatever covering is used, seed that is broadcast sown should be

.pressed slightly into the soil with a roller before

covering.

Sand to be used as a cover should be thoroughly

tested to see that it is at least slightly acid. The test

is made with a few drops of 10 to 20 percent hydrochloric acid. If the material fizzes, the sand is not

desirable for use as a cover, since it is likely to increase

damping-off disease.

Sands that are acid or neutral in reaction are scarce

in the Great Plains, especially in the western part.

Sands from subsurface layers of soil, which are more

free of weeds and disease, tend to be even more alkaline

in reaction. Some dune sands in the Plains may be

leached of carbonates to a depth of 4 to 6 feet; these

are suitable as seedbed covers. In areas of extensive

heavy soils, sometimes the only suitable sandy material is in the surface 6 to 10 inches of the sandiest

field that can be found.

Where no acid sands are within easy hauling distance of the nursery, Davis ( 1940 ) suggests that in

lieu of using alkaline sands, the nurseryman drill sow,

surface sow with burlap mulch, or broadcast sow with

sawdust as a seed cover.

If straw or any type of hay is used, it should be as

free as possible from weed seed. If such material is

hard to obtain, the nurseryman could well grow some

rye or oats in the nursery and mow it before seed has

formed in order to assure a supply of mulch free from

weed seed (fig. 22).

F-502091

FIGURE 22 —Application of a layer of straw on top of cotton commodity cloth in fall-sown beds, Bessey Nursery,

Halsey, Nebr.
30 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

Mulch applied to fall-sown beds serves die following

purposes:

1. It conserves moisture and reduces soil drying

and cracking. . .

2. It prevents fall germination by reducing soil

temperatures at seeding depth. ^ ^

3. It retains soil temperature in the 33° to 50° F.

range longer, and by preventing soil freezing

in late fall or early winter, it provides a longer

period of afterripening under conditions similar to controlled temperature stratification.

4. It reduces soil blowing and uncovering or deep

burial of seed.

5. It prevents early spring germination.

At least one commercially manufactured sand

spreader is available for use on broadcast-sown beds.

However, most nurseries use homemade devices. A

simple one consists merely of a frame, 2/2 by 3 feet,

with the long sides extending a foot or more beyond

each end to make the handles. The bottom of die

frame is covered by 14-inch-mesh galvanized hardware cloth. Sand or sandy soil from the paths is

shoveled onto the screen, which is shaken by two men.

A tractor-drawn endless-belt sand spreader was devised by Olson (1930). Bull (1954) describes a

reciprocating sifter, suitable for sifting sand or sawdust, which is actuated by a camshaft and mounted on

a trailer (fig. 23). The Savenac Nursery has devised

an automatic trough sander, which is towed behind a

dump truck from which the sand drops into the sander.

Any chemical treatments with liquid materials, such

as acidification with dilute sulphuric acid or aluminum sulphate or postseeding weed-control drenches,

should be applied after the seed is covered with sand

or soil and before the burlap or any other mulch is

applied.

F-502093

F-505892

FIGURE 23.—A reciprocating sifter, Towner Nursery, Towner,

N. Dak.

FIGURE 24.—Pinning down burlap on newly seeded beds to

conserve moisture and assure prompt, uniform germination, Bessey Nursery, Halsey, Nebr. Burlap covering also

prevents wind erosion. Looped pins of galvanized iron

wire are preferred, as they can be re-used.

Newly seeded beds are commonly protected with

covers between seeding and germination. Soil moisture levels favorable for germination can be maintained with less watering. Use of burlap has been

quite successful with the more rapidly germinating

pines, especially in spring seedings (fig. 24). More

recently, polyethylene film has been employed as a

bed covering; it has an outstanding ability to virtually

preclude any moisture loss from the beds. Burlap

alone does not do this well, especially on fall sovmigs.

A combination of polyethylene film covered by burlap

prevents tearing of the film by wind and, by reducing

soil freezing, increases the time the fall-sovwi seed is

exposed to the beneficial afterripening effect of soil

temperatures in the 33° to 50° F. range.

The life of burlap is extended by treating it with

copper naphthenate (Anderson and Kineer 1949).

After use, it should be dried thoroughly, beaten to remove excessive soil, and rolled for storage. A special

burlap reel can be used advantageously ( Stoeckeler and

Jones 1957).

Five stages of nursery operation, including preparing the seedbed, seeding, rolling, seed covering, and

sifting sand, are illustrated in figure 25. The methods

shown represent an intermediate stage of development

of nursery equipment that gave an accuracy of depth

control in seeding seldom achieved by the more mechanized methods now commonly used, especially in the

larger nurseries.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 31

SEEDBED CARE DURING GERMINATION AND THE SEEDLING STAGE

The seed germination stage of about 10 to 30 days

is most critical because the tender seedlings are easily

injured. Mulches must be removed in the spring after

the danger of killing frosts has passed. If allowed to

remain in place until germination is well advanced

and after the seedcoats appear above ground, the

mulch interferes with early growth, and its removal

from the bed is accompanied by mechanical damage.

Great care must be used in taking up burlap or in

raking straw mulches from the seedbed. Fiber or wiretined rakes are less damaging than ordinary garden

rakes. Complete removal is desirable since losses of

seedlings are apt to occur as a result of excessive moisture and the root rot disease favored by the decomposition of the mulch.

HALf-SHADE

Half-shade is needed in Prairie-Plains conifer beds,

particularly by the more delicate and smaller seedlings during the first season. It is common practice to

shade all species except ponderosa pine and occasionally Austrian pine. These two species are more

heat resistant and are often grown without shade.

Half-shade prevents heat and drought injury, reduces

water use, and minimizes soil drying (Hartley 1918,

Stoeckeier and Jones 1957, Toumey and Korstian

1942). When placed directly on bedboards, it also

excludes rabbits and dogs. Any half-shade tends to

confine the intrusion of larger mammals, such as deer,

to the paths.

Four separate experiments at the Towner Nursery

showed that no advantage was to be obtained by shading p)onderosa pine during the first year. The trends,

when analyzed separately for each exjjeriment, were

nonsignificant statistically, but the stands, as noted

below, were consistently greater in the unshaded beds.

No shade Half-shade

Plots ' {trees per {trees per

Experiment Number square foot) square jnot)

A 48 78.9 75.1

B 64 54.6 46.0

C 64 61.2 57.2

D 32 52.2 45.8

Average 61. 7 56. 0

1 Size of plots: A, 4 by 12 feet; B, C, and D, 2 by 4 feet.

F-439905

FIGURE 25.—Various seedbed operations are illustrated here, .^jsht background: pr^^^ Center foreground:

track. Center background: operating a 10-spout seeder, with seedbed ^°"«[j '°' ^^gj^ screen into sand-carrying tray,

operating a sanding machine. Right foreground: sifting sand with a slanting porta
32 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

Two experiments at the Towner Nursery compared

the presence and absence of shade on the basis of tree

percent of viable seed sown (fig. 26). Unshaded beds

produced higher tree percents, except for high-density

sowings in one of the studies.

Jack pine, however, does best under shade. In a

study at the Towner Nursery, shaded beds consistently

had a denser stand than unshaded beds and were substantially better at the higher rates of viable seed sown

(fig. 27).

The advantages of shading are considered to be

even greater with spruces than with jack pine, since

the former are slower growing and more delicate than

pine. Some nurserymen leave half-shade on secondyear spruce until mid-September. The need for shade

is somewhat dependent on the season of sowin;^ and

on watering frequency. Fall-sown seeds germinate

more promptly than spring-sown ones. Trees, therefore, are larger and have thicker stems by early

summer, and less heat injury occurs.

Almost all nurseries use slat-wire snow fence for

half-shade. For high-shade, snow fence may be placed

on two tightly drawn pieces of No. 9 wire supported

on 30-inch posts driven into the ground with 1- by 2-

inch crosspieces at intervals of about 12 feet (fig. 28).

The snow fence is 12 to 20 inches above the ground.

It must be wired together and drawn fairly taut at

the ends. Some nurserymen take the additional precaution of attaching it to the No. 9 wire at intervals of

about 25 to 30 feet to keep it from being thrown ofif

the wires in high winds. If a third wire is run down

the middle of the beds, upright supports can be at

least 15 feet apart (Sharkey 1956).

Where bedboards are used, the snow fence is rolled

directly on top of them. This lower shade is not quite

as effective as higher shade because the strips of seedbed are exposed longer to full sunlight and there is

less free air movement under the snow fence. Heat

injury occurs occasionally when half-shade is positioned at a height of 4 or 6 inches.

A few nurseries use rigid shade frames. The Bessey

Nursery, for example, uses individual 4- by 12-foot

shade frames made of lath nailed to 2- by 25^-inch

stringers—one on each long side. These shade frames

are supported on each of the four corners by a piece

of 1/2-inch angle iron 3 inches long that has been

welded to the top of a 22-inch-long five-eighths-inch

bolt. The bolts are pushed into the ground about 6

inches.

SOIL MOISTURE AND IRRIGATION

The amount of water applied in a nursery will vary

by water-holding capacity of the soil, annual precipitation, air temperature, humidity, wind, species, and

age of stock. Each soil has a specific water-holding

capacity, and only enough water need be added to raise

It to field capacity. For sands, this value is about 8 to

12 percent; for loamy sands, 12 to 15 percent; for sandy

loams, 15 to 25 percent; and for silt loams, 25 to 35

percent. Excessive watering tends to leach out soluble

50 100 150

VIABLE SEED SOWN (NUMBER PER SQFT.)

200

FIGURE 26.—Tree percent in 1-0 ponderosa pine beds in two

separate experiments (I and II) in shaded versus unshaded beds over a range of sowing densities, Towner

Nursery, Towner, N. Dak.

160

a

ÜJ

0.

:I40

120

< 100

o

z

-j

a

u

u

O

<

z

80

60

>

/ /

^/

/

/

/

/

/

/

/ /

^/

7

/

r

A

/ y' / r

/ y

/ /

i y

40

66 99 132 165 198

VIABLE SEEDS SOWN (NUMBER PER SQ.FT.')

FIGURE 27.—-Effect of half-shade on a stand of first-year jack

pine seedlings over a range of sowing densities, Towner

Nursery, Towner, N. Dak.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 33

F-342193. 342194

FIGURE 28.—A, Round posts and crosspieces for half-shade

support; B, the half-shade in position, Fremont Nursery,

Fremont, Nebr.

nutrients, especially nitrogen and potash, and results in

unnecessary use of water and power.

The amount of water to use on trees, particularly

from midsummer on, or when the tree roots are at least

3 or 4 inches long, can be gaged by use of a tensiometer.

This device consists of a porous ceramic cup fitted to a

vertical aluminum or plastic tube to which is attached

a sealed vacuum gage (fig. 29).

The entire system is filled with clean water, and the

porous cup is buried in the soil in the rooting zone.

Water moves through the porous cup to the soil until

the tension or suction pull is equalized. The amount

of pull is registered in the vacuum-gage dial pointer.

The scale ranges from 1 to 100, and represents tension

values from 0 to 1.0 atmosphere. Watering of beds is

started as soon as the f>ointer gets into the 50 to 60

range. The tensiometer needs occasional filling with

water. It may or may not be kept in one place, but

about 8 hours must elapse before equilibrium is

reached. Hence, it is desirable to have a tensiometer

for first-year seedbeds, one for second-year beds, and

another for transplants. If texture varies considerably, checks of moisture content must be made in

several situations. Slight knolls that are exposed and

very sandy soils will dry out faster than flat areas or

those with a higher silt-plus-clay content (Stoeckeler

and Aamodt 1940).

Soil moisture content can also be gaged by electrometric methods devised by Bouyoucos (1956) and

Colman ( 1947), by oven drying or use of Livingston

soil points (Stoeckeler 1939), or by the alcohol-burning

method (Bouyoucos 1937).

Under nursery conditions, especially during active

growth, soils should never be allowed to dry to the

wilting point. Preferably they should have at least

2 to 3 percent of moisture in excess of the wilting point

in sands and 4 to 5 percent in excess in sandy loams.

Excessive soil dryness can weaken plants, while excessive watering tends to reduce drought resistance (Shirley and Meuli 1939, Stoeckeler 1951a). For example,

where 2-0 jack pine were grown under four levels of

watering in the nursery, optimum drought hardiness

was achieved by those trees in seedbeds with an average

available moisture content of about 5 percent from

June 1 to September 15, or a total average soil moisture content of about 8.5 percent for a soil with a siltplus-clay content of 10 to 12 percent (Stoeckeler

1951a). Among western species, Roeser (1940)

determined that the water requirements of spruce and

fir were considerably higher than those of ponderosa

or limber pine.

Correct watering from germination to the time when

root length is at least 3 or 4 inches and stems are moderately resistant to heat injury is difficult to gage instrumentally, and the nurseryman should rely on keeping

the surface of the bed moist by light daily or twice daily

watering. The ends of beds on the windward side may

require hand watering with a hose. At the Bessey

Nursery, first-year conifers are watered twice a day for

the first 4 to 6 weeks; 0.15 inch is applied in the early

morning and the same amount in the late afternoon.

Thereafter, one watering is made per day, unless the

beds are moist from rain.

Two-year-old stock requires watering about every 4

(«"ri

FIGURE 29—TWO instruments for soil moisture determinanon The soil mosture meter on the left works on the

ên"iometer principle; it measures comparative soil dry^

ness in terms of suction pull of the soil. The moisture

meter on th^ right gages soil moisture electromemcally by

measuring resistance of current through buried gypsum

blocks.
34 AGRICULTURE HANDBOOK 2 79, U.S. DEFT. OF AGRICULTURE

days, and transplants at least once a week; enough

water is applied to soak the soil to an 8- to 10-inch

depth. The amount required varies from 0.3 to 0.8

inch. In sand, 1 inch of water will wet the soil to a

depth of about 1 foot (Woodward and Gilden 1:955).

The depth of wetting will depend on the soil moisture

content when watering is started.

Near the end of the growing season, the trees are

watered only once every week to 10 days to harden off

the stock, reduce succulence, and increase frost hardiness. This hardening-off process begins in late August

in the Northern Plains, in mid-September in the Central Plains, and in late September or early October in

the Southern Plains,

^VEED CONTROL

Weeds are a constant problem in nurseries and must

be systematically eliminated by hand picking, by the

use of hand-pushed or power-operated cultivators, or

by the application of chemicals. Many nurseries use

all of these methods.

Mechanical and Hand W^eeding

In new seedbeds hand weeding is often used as a

mopup operation after chemical weed control. Weeders may work in pairs on the same 4-foot-wide beds,

each taking half the bed and working systematically

from one end to the other, or each may have an assigned unit, consisting of one-fourth or one-half the

length of the bed. The weeds are pulled by hand and

dropped into boxes or collected later from piles in the

paths. Deep-rooted, hard-to-pull, or persistent weeds,

or those that break off, are dug out or cut off 1 inch

or more underground with a steel cutter fixed into a

loop attached to a wooden handle (Engstrom and

Stpeckeler 1941), an old table knife Ibent into an Lshape (Tennessee Valley Authority 1954), or a similar

handtool. Paths are cleaned with a push hoe or with

wide sweeps attached to a rubber-tired tractor.

After the trees are about 6 weeks old, seedbeds sown

in drills with a 4/2- to 6-inch space between drills can

be cultivated with power-drawn rotary weeders

(McDaniel 1954, Mony 1954, Stoeckeler and Jones

1957, and Umland 1946).

Transplants in rows spaced 10 inches or more apart

are usually straddle cultivated by a battery of ordinary

farm cultivator shovels mounted on a tractor. In this

operation, all the rows in a 4-foot bed are cultivated

simultaneously. Where the row spacing is uniform

and wide enough to accommodate a rubber-tired tractor, the rows can be cleaned with multiple-row cultivators to minimize damage to the trees. In transplant

beds, four to six cultivations a year are needed to keep

the weeds down.

Weeding should start when the weeds are quite

small. Weeds 1 to 2 inches tall are eradicated much

more readily than larger ones, and minimum damage

to trees occurs. To reduce root breakage, beds should

be made reasonably moist before weeding.

Chemical Control of WeeAs

Chemical weeding is used much less in Plains nurseries than elsewhere. Wider use could reduce stock

costs. Chemicals used rather extensively for weed control in forested areas include mineral spirits, allyl alcohol, and methyl bromide. Other chemicals being

tested show promise. The generally rapid advance in

the use of chemicals to control agricultural weeds is

bringing additional benefits to nursery practice.

Safety rules and precautions for handling, mixing,

and applying chemicals are given in the Appendix.

All nurserymen should be thoroughly familiar with

these rules and should see that adequate precautions

are taken when any chemicals are handled.

Mineral Spirits

Mineral spirits are petroleum products that are used

as selective herbicides in many conifer nurseries (Robbins et al. 1947, Stoeckeler 1951b and 1952b, Wycoff

1954). When used in proper amounts, they kill small

broadleaf weeds and grasses without harming the evergreens. They can be purchased from most bulk gasoline distributors.

Undiluted mineral spirits are applied with pressure

sprayers as a fine mist at a pressure of 50 to 100 pounds

per square inch, generally at the rate of 25 to 75 gallons per acre (table 7). On a small scale they can be

applied with a 1- or 2-gallon pressure sprayer. They

are most effective if applied three to six times per season when the weeds are small, preferably about onefourth to 1 inch tall. Taller and older weeds are

more resistant to oil sprays.

TABLE 7.—Dosages of mineral spirits used on conifer

species in the north-central Prairie-Plains

Age

Species

3 to 6

weeks

6 weeks

to 1 year

1 year

and

older

Juniper, Rocky Mountain. . .

Pines:

Austrian

Gal.¡acre

25

25

40

25

40

40

25

25

30

25

Gal./acre

30

30

50

30

50

50

30

30

50

30

Gal.¡acre

40-60

40-60

Jack 60

Ponderosa 40-75

Red 60

Scotch 60

Redcedar, eastern 40-60

Spruce :

Blue 40

White 60

White (Black Hills) 40

The mineral spirits must be applied as a fine mist,

and at a dosage reasonably near the optimum for the

specific age class and species. The temperature at the

time of spraying is also important. In the absence of
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 35

specific information from Plains nurseries, it is recommended that application should not be made when

air temperature exceeds 80° F., a limit that has been

found safe in Lake States nurseries. Trials conducted

over a period of years have helped to determine effective applications at individual nurseries.

Mineral spirits w^ere first used in the Bessey Nursery

in June 1948. They v/ere applied with a Bean sprayer

at 200 pounds pressure, using about 50 to 80 gallons

per acre on seedlings and 80 to 115 gallons per acre on

transplants. Weed kill ranged from 50 to 100 percent.

Good kill was obtained on lamb's quarters, primrose,

barnyard grass, crabgrass, foxtail, sandbur, fescue, and

pigweed. The following species were rather resistant

to the spray: Panic grass, rye, ragweed, pepper grass,

sunflower, nightshade, sage verbena, plantain, clover,

and wood sorrel.

By 1951, dosages as low as 25 to 50 gallons per acre,

sprayed when weeds were quite small (usually less

than 1 inch tall), were giving up to 90 percent weed

kill. These lower dosages reduced weeding costs 35

percent. Injury to seedlings was generally small, although occasionally about 5 percent of the trees showed

some temporary yellowing that usually disappeared

within 1 month. Mortality has been under 1 percent,

or less than that normally lost in ordinary hand weeding and machine cultivation.

Seedlings less than 6 weeks old are more subject to

injury from mineral spirit sprays, and special precaution must be taken with them.

At the Oklahoma State Nursery, excellent weed control has been obtained by application of mineral spirits

two or three times a season in amounts as low as 12 to

15 gallons per acre. The mineral spirits were applied

as soon as the secondary foliage appeared on the seedlings. Eastern redcedar and Austrian, ponderosa,

shortleaf, and loblolly pines are among the species

sprayed.

If weeds have emerged but the tree seedlings have

not, excellent control with complete safety may be obtained by spraying the weeds with 50 to 60 gallons per

acre of mineral spirits.

Methyl Bromide

Methyl bromide is a gas injected under polyethylene

film or gasproof cover before seeding. Developed for

disease control in forest tree nurseries, it has been very

effective as a weed control on seedbeds in which firstyear seedlings are produced. It has virtually eliminated all weed growth for 22 days or more after the

tree seed has been sown (Stoeckeler 1951c). In the

usual treatment, 1 pound per 100 square feet of bed

area is used ; however, the dosage may vary from onefourth to 1^ pounds, depending on the kind and

severity of weed infestation and the soil texture (Mony

1961). In tests at the Towner Nursery in North

Dakota, one-half pound applications reduced weed

numbers by two-thirds, a degree of control equal to

that obtained with dosages of 1 to 1 yi pounds. Air

temperatures should range between 50° and 80° F.,

and a high moisture content of the weed seeds is essential for control.

Total costs, which include those for labor, gas, and

plastic covers with a 2-year life, have averaged $234

per acre in Indiana. This was 67 percent of the cost

of other chemical methods and 50 percent of the cost

of solvent oil and sulfuric acid methods (Monv

1961).

Allyl Alcohol

Allyl alcohol has had excellent effect as a preseeding

treatment when applied about a week before seeding.

Also, no covers are needed. It can be applied at the

rate of about 10 gallons of the concentrated chemical

in 5,000 gallons of water per acre (Maki and Allen

1952, Steavenson 1952, Stoeckeler et al. 1951). Experience in Plains nurseries is lacking. In small-scale

operations, it has been applied in 0.2 percent solution

by volume with sprinkler cans or acid sprayers. On

large-scale operations, the safest method appears to

be that of Lanquist (1951), who injects a 10-percent

mixture by volume of allyl alcohol in water through

the riser end of the overhead irrigation system. The

mixture is injected at the rate of 50 gallons per 400

feet of pipeline ; watering is then used to obtain further

penetration into the soil.

Miscellaneous Chemicals

Zinc sulfate (Wahlenberg 1930) has been used as

a postseeding drench, at 8 grams per 250 cubic centimeters of water per square foot of seedbed, and has

given 80 percent weed reductions. However, some

chemical injury has been reported in dry seasons or

during water shortages; spruce has been especially

affected (Dejarnette 1936). Sulfuric acid has given

good weed control, and it is considered safer than zinc

sulfate, because of the possibility of zinc toxicity.

A 4-percent solution of formaldehyde, at 1 gallon

of solution per square yard, applied as a drench well

before seeding, has given good weed and damping-off

control (Holmes and Ivens 1952).

Simazine has been used successfully for weed control

in Minnesota nurseries, Stadtherr and Coultas

(1961) applied one-half to 1 pound per acre as a

postemergent treatment to conifer seedbeds on a heavy

loam soil. Application of 1 to 2 pounds per acre was

used in the second year after transplantmg. Two

applications were made on the transplants, one m May

and the other in mid-July to August. On sandy soils

some injuries followed its application. This chemical

may warrant small-scale trials under Praine-Plains

conditions.

Other chemicals reported successful as nursery weed

controls are vapam, applied at one-half or 1 quart in

21 gallons of water per 100 square feet (Briscoe and

Strichland 1956) ; ferbam, at 500 pounds per acre in

10,890 gallons of water (Allen 1952) ; and 2,4-D,

at 6 pounds per acre, as a preseeding or preplanting

control (Clifford 1952).
86 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

POSSIBLE HARMFUL EFFECTS OF

CHEMICALS OIV TREES AND SOIL

In recent years chemical corporations and research

chemists have developed scores of new chemicals for

weed, insect, and disease control. Overdoses of these

chemicals or their cumulative effects may adversely

affect tree stand, tree growth, or beneficial soil organisms (Gambrell and Heit 1952, Theigs 1955, Voigt

1953, Wilde and Persidsky 1956). The nurseryman

is advised to use conservative dosages found by repeated trials to be entirely safe for the crop he is growing. Manufacturers' recommendations should be

checked at State and Federal experiment stations.

If experiments are undertaken with chemicals still

being evaluated, only small areas should be treated.

Usually application should be limited to a few hundred square feet in the form of small replicated plots.

At Towner Nursery, monuron (3-(p-chlorophenyl)-l,

l-dimethylurea), used as a preseeding treatment in a

weed-control experiment, was deleterious to eastern

redcedar. There was a 60-percent kill of trees at 1

pound per acre, 80 percent at 2 pounds, and 95 percent at 3 pounds. Experiments must be repeated for

several years on areas of different soil textures since

weather and soil moisture content affect the action of

some chemicals.

A good point to remember is that organic matter in

the soil has a counteracting effect on the harmful

action of many biocides (Voigt 1955).

TRA]VSPLA]VTING

Transplanting is a standard practice in almost all

Great Plains conifer nurseries. Its primary purposes

are to produce more fibrous root systems, thicker,

sturdier stems, and better balance between roots and

tops. More food is stored, the enlarged stems stand

erect, and the more fibrous root system absorbs more

moisture and food from the soil. Such plants often

have 20 to 30 percent better survival than seedlings.

Transplanting usually is done when the seedlings are

3 to 5 inches tall. Some of the factors contributing to

a good transplant job are good soil tilth, a smooth, level

bed, and accurate and regular row alinement.

The method of lifting the seedlings for transplanting

is the same as that for field planting. It is described

under "Digging, Grading, Packing, Storing, and Shipping." After lifting, the roots are pruned, in small

bunches, to a uniform length, usually about 6 inches.

The trees are then placed in boxes, ready for transplanting.

Both hand and machine methods of transplanting

have been used. The method depends on the size of

the nursery, soil texture, amount of transplanting to be

done, and the funds available for mechanization.

Some of the hand methods have been highly efficient,

and under some conditions the production rate has

been exceeded very little by using transplant machines.

Whether hand or machine planted, the trees should be

watered thoroughly on the day on which they are

transplanted.

HAND TRANSPLANTING

Hand transplanting is done across the beds in short

rows or lengthwise in continuous rows 100 to 500 feet

long.

Trenches are made in the soil with a hand or tractordrawn trencher. A hand-trenching tool consists of

two thin steelplates welded together, sharpened at the

bottom, and fitted with galvanized iron handles (fig.

30^ ). Several nurserymen have modified small garden plows or pony plows so they will make a verticalwalled open trench for transplanting in long rows with

the conventional transplant board (Jones 1925, Corson

1935).

The trenches should be deep enough and wide

enough to accommodate the tree roots in a vertical

•mCfjKfi^.-^..

F-36192S. 381927

FIGURE 30.-Equipinent for hand transplanting: ^ Hand trenchers formerly used at the Bessey Nursery; B. details of "the

construction of an aluminum transplant board.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 37

position without curling. Crossbed trenches should

be about 6 inches longer than the transplant board.

The proper amount of soil moisture will prevent the

sidewall from sloughing or caving in, in the interval

between trenching and planting. Coarse, unrotted

plant residues will interfere with the formation of a

clean trench ; hence, such materials should be plowed

under early enough to decompose or should be removed

from the site.

Seedlings are threaded into transplant boards with

notches I'/a to 2 inches apart (fig. 30B) (Fox 1940,

Olson 1930, Schrader 1938). To protect the plants

they are threaded inside a light, portable shelter. A

hinged upper clamp on the board swings down to hold

the trees in place while the board is carried to a trench.

The tree roots should always be kept moist. The roots

will be less exposed if the walking distance from the

shelter to the transplant bed is kept less than 50 feet by

moving the transplant shelters frequently or by assigning short sections of bed (about 60 to 100 feet) to each

planter if the rows are long.

In planting, the board is lowered with a swinging

motion—to and fro—in the trench and parallel to it.

After the roots are hanging vertically, the board is

adjusted for depth so that the trees are planted onefourth to one-half inch deeper than they were in the

seedbed (fig. 31). The trench is closed with the feet

or a tamper; looseness around the roots must be prevented. Heel marks and depressions are smoothed by

adding loose soil between the transplant rows.

When long boards (8 to 10 feet) are used, the transplant area must be exceptionally smooth and level so

that all trees are placed at the proper depth. With a

10-foot board with 80 notches at I/2 inches, Oliver

(1937) reported that an average of 8,600 trees per

8-hour man-day were transplanted in hand trenches

across the bed. Olson (1930) reported using an 8.5-

foot board with 75 notches, but the planting was done

the long way of the bed in an open, vertical-wailed

trench made with a small 7-inch horse-drawn plow.

The crew average was 11,000 trees per man-day.

Dejarnette and Augenstein (1946) produced 11,500

trees per man-day by the same method. Six two-man

crews were used; a threader and planter worked in

each row.

At the Bessey Nursery, hand transplanting in recent

years has been done with a 6-foot-long board containing 60 notches. A 20-man crew was employed; it

consisted of 10 threaders, 5 planters, 3 trenchers, 1 tree

carrier, and 1 foreman. Trenching was done by hand

across the bed with a mast trencher 26 inches wide.

One trencherman worked in each group of five beds,

while each planter confined his work to three beds,

planting each trench as it was opened by the trenchermen. Planting coops, each with two threaders, were

kept within about 50 feet of the transplanting work.

The crew planted" 150,000 to 175,000 trees per 8-hour

day.

Recently, the Bessey Nursery has started transplanting the long way of the bed. Each bed has seven rows

F-406424. 385794

FIGURE 31.—Two methods of hand transplanting. A, Planting 1-0 eastern redcedar across the bed, using a board

about 6 feet long; man in foreground is trenching and the

man nearest him is firming the soil around the roots of

the trees, Bessey Nursery, Halsey, Nebr. B, transplanting

ponderosa pine in long, continuous trenches made by

tractor-drawn trenchers; this method is well adapted to

subsequent mechanical cultivation, Towner Nursery,

Towner, N. Dak.

spaced 7 inches apart; thus, the standard lifter for 4-

foot-wide seedbeds can also be used on transplant beds.

MECHANICAL TRANSPLANTING

Mechanical transplanting is accomplished with the

Holland Seedling Transplanter, "New Idea" vegetable

planter, or a similar type of machine. The so-called

"mechanical transplanter" is not fully automatic^

Each seedling must be handled individually and placed

in a self-closing pocket on a revolvmg metal disk, or

between two self-closing revolving disks. Normally

two rows are transplanted at a time, but the number

can be increased to seven (Hanks 1962) by mounting

additional transplanting units on a special carnage

(fig. 32).

The transplanting machine has many advantages;

the chief asset is the elimination of the heavy manual

labor involved in hand trenching and trench closing.

Since mechanical trench opening and closing are combined in the same operation, the trench is left open

to drying for an absolute minimum length of time.
38 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

FIGURE 32.—Seedling transplanter used to transplant seven

rows at a 7-inch spacing in one operation. The method

permits the lifting of seven rows at a time with the same

lifter used for seedbeds. It also permits efficient mechanical cultivation of seven rows at a time by a bed-straddling

tractor. Bessey Nursery, Halsey, Nebr.

The tree roots are exposed to the air much less than

in hand transplanting, where no protection of the

threaded boards being moved from the transplant

coops to the planting trench is possible. Transplanting can be done by crews of women; they are more

nimble fingered than men in feeding seedlings into

the planter. When the transplanting machine is used,

less training, teamwork, or balancing of crews is required for maximum efficiency. Furthermore, the

machine is geared to a specific speed (usually about

11 feet per minute), and the planters must keep up.

The trees are set by the mechanical transplanters

1/2 or 254 inches apart in the row. The wider

spacing permits trees, especially 2-2 or large 2-1 stock,

to be separated with a minimum of root stripping when

they are lifted. Batteries of transplanters pulled by

one power unit may transplant two to seven rows during one trip over the beds. Uniform spacing between

rows is obtained; thus, the trees are less likely to be

damaged during later cultivation.

Transplant machines usually set about 10,000 trees

per person per 8-hour day. Thus, use of these machines results in production only equal to or a little

greater than that obtained by use of some of the most

efficient transplant-board methods already mentioned,

particularly those where long trenches are made by

horse- or tractor-drawn trenchers. Mechanical transplanting has been widely adopted by the nursery industry, largely because of a shortage of labor for hand

transplanting.

TRANSPLANT SPACING

Spacing within the transplant rows of at least 11/2

inches is desirable. This interval has been determined

from spacing experiments and general observations on

stock quality, ease of separating roots, and freedom

from root stripping.

Janouch (1927), studying spacing in 2-1 jack pine

and in 1-1 and 2-1 ponderosa pine, concluded that

6- by 15/2-inch spacing at the Bessey Nursery was

nearly ideal and that 6- by 2-inch spacing was slightly

wider than needed. He based these conclusions on

subsequent field survival of the stock.

A comprehensive study of transplant spacing was

initiated in the Towner Nursery in the spring of 1939

by personnel of the Lake States Forest Experiment

Station. The species involved were ponderosa pine

and Rocky Mountain juniper. Four spacings within

the row (1, I/2, 2, and 4 inches) and four spacings

between rows (6, 12, 18, and 24 inches) were tried in

all possible combinations.

A sample of junip>er stock was lifted and measured

after 1 year in the transplant bed ( table 8 ). Based

on a caliper limit of one-eighth inch for a plantable

tree, a spacing of at least 6 by 1 ^2 inches, or 9 square

inches per tree, was necessary to yield a fairly high

percentage of plantable stock. The 2-inch space between trees had a marked advantage over l/a-inch

spacing when row spacing was 1 foot or less.

When the juniper stock was lifted at the 2-2 age,

the maximum production of usable stock occurred at

the 6- by 1-inch spacing. All spacings gave at least 75

percent plantable stock. The top-root ratio was a little high, generally 4.0 to 5.0, which is not as good as

it was at the 2-1 stage. The largest percentage of

premium stock (using caliper as a criterion) was produced at a spacing of at least 12 by 2 inches.

Considering all factors of cost and performance,

there seems to be no need for growing 2-2 Rocky

Mountain juniper at a spacing greater than 6 by 2

inches. The usual spacing attained by mechanical

transplanters should produce uniformly good stock but

with less efficiency than that obtained with closer

spacing between rows.

The ponderosa pine in the spacing experiment were

all grown to the 2-2 age (table 9). The stock measurements showed that 6- by 1 /2-inch spacing produced

good-sized stock of adequate height and stem caliper.

All of the trees were slightly more top heavy than was

desirable because of exceptionally favorable growing

conditions in the fourth year.

The percentage distribution by stem caliper for 2-2

stock of two conifer species is given in table 10. Apparently, if a considerable proportion of the trees are

to have a stem caliper of one-fourth inch or more,

spacings of about 6 by 2 inches or larger are necessary.

TRANSPLANT LOSSES

In transplant beds, some of the trees die despite

careful handling. To compensate for these losses, the

amount of stock transplanted must be increased.

At the Savenac Nursery in Montana, the loss in ponderosa pine has been 3.1 to 30.0 percent (Fox 1937,

1939; U.S. Forest Serv., Rocky Mountain Region

1931 ) and is generally 10 to 20 percent. In the Northern Prairie-Plains, junipers and redcedars have had
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 39

TABLE 8.—Effect of transplant spacing on size and grade of 2-1 Rocky Mountain juniper, Towner Nursery,

Towner, N. Dak. The transplanting was done in the spring of 1939 and trees were measured in the

spring of 1940

Spacing (inches)

Average length Average

stem

diameter

Green weight

Usable

stock 1

Premium

Top Root Total

Top-root

ratio

stock 2

6 by 1

Inches

11.0

9.3

12.5

9.5

10.1

9.5

9.9

11.0

9.5

11.6

10.9

10.8

12. 1

9.7

9.9

11.0

Inches

11. 1

10.9

11.0

9.5

9.6

10.0

9.5

12.3

8.9

10.2

11.0

9.3

12.0

9.8

9.0

12.4

64ths inch

9

11

15

14

11

12

15

17

11

14

14

18

13

13

14

17

Grams

21

22

34

28

18

28

33

30

41

58

36

46

29

29

33

56

3.2

2.8

3.2

3.0

3.3

3.0

3.6

3.4

4.9

3.6

3.9

3.8

3.6

3.5

3.4

3.7

Percent

73

97

100

100

90

93

100

100

87

100

97

100

93

97

100

100

Percent

17

í; Kv 1U 47

<; hv 2 86

6 by 4 77

1 0 hv 1 33

1 9 hv 1U 61

12 by 2 80

12 by 4 97

1 « hv 1 43

1ft hv 1U 73

18 by 2 70

13 by 4 93

24 by 1

57

24 bv 1^ 70

24 by 2

70

24 by 4

97

1 Trees with a stem diameter of at least %4 inch. 2 Trees with a stem diameter of at least i%4 inch.

TABLE 9.—Effect of transplant spacing on size and grade of 2-2 ponderosa pine, Towner Nursery, Towner,

N. Dak. The transplanting was done in the spring of 1939 and trees were measured in the fall of 1940

Spacing (inches)

6 by 1. .

6 by 1/2.

6 by 2 . .

6 by 4..

12 by 1.

12 by IV2

12 by 2.

12 by 4.,

18 by 1.

18 by 1/2

18 by 2.

18 by 4.

24 by 1.

24 by IK

24 by 2,

24 by 4.

Average length

Top

Inches

7,2

9.0

7.9

9.3

10.3

8.5

8.2

8.0

5.8

8.0

7.9

10.2

8.5

8.8

8.8

8.5

Root

Inches

12.3

12,2

13. 3

13.3

12. 3

15.8

14.3

14.6

13.5

14,7

16.8

15.1

15.1

15.8

15.7

15.0

1 Trees with a stem diameter of at least %4 inch.

losses of 5 to 15 percent; and spruces, losses of 15 to 25

percent. At the Bessey Nursery in Nebraska, losses in

the first-year transplant beds have been about 10 percent, with a usual range of about 4 to 15 percent.^^

^Personal communication with M. K. Meines, Nurseryman, Halsey, Nebr.

Average

stem

diameter

6Á.ths inch

16

18

18

21

15

18

20

20

15

16

19

23

19

18

21

21

Green weight

Total

Grams

26

37

38

63

22

45

58

59

24

32

57

94

49

50

72

63

Top-root

ratio

4.3

5.2

5.2

5.4

4.1

5.3

4.8

5.0

4,1

5.3

4.9

5.9

4.1

5.5

4.9

4.5

Usable

stock ^

Percent

100

80

100

100

90

90

100

90

90

95

85

100

100

90

95

95

Premium

stock 2

Percent

50

65

90

85

25

75

95

75

45

55

55

88

90

60

70

80

2 Trees with a stem diameter of at least i%4 inch.

Each nursery must develop an experience table (see

table 11) of first-year transplant losses by species and

ace class since season of transplanting, method oí

transplanting, and other factors affecting survival vary

considerably over the Prairie-Plams.

Transplant losses are minor after the first season

in the beds.
40 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

TABLE 10.—Percent of trees over a given caliper

class in 2-2 juniper and 2-2 ponderosa pine ^

TABLE 11.—Average first-year losses in transplants at

the Bessey Nursery^ Halsey, Nebr., 1943-1956

Spacing

(inches;

2-2 juniper with a

caliper of at least—

2-2 ponderosa pine with

a caliper of at least—

inch

«/32

inch

'%2

inch

%2

inch

%2

inch

^%2

inch

6 by 1... .

6 by m..

6by2....

6 by 4....

12 by 1...

12 by lU.

12 by 2...

12 by 4...

18 by 1...

18 by m,

18 by 2...

18 by 4...

24 by 1. ..

24 by 11/2.

24 by 2...

24 by 4...

Percent

97

99

93

99

97

97

100

99

98

98

100

100

92

99

98

100

Percent

30

33

53

70

33

49

54

88

48

71

74

83

55

53

58

84

Percent

1

3

8

18

2

5

9

40

13

21

27

44

16

11

13

47

Percent

92

99

99

97

94

100

97

100

87

99

99

100

97

96

99

100

Percent

41

59

63

59

50

62

69

79

44

63

70

83

55

53

74

84

Percent

3

10

12

14

19

23

21

46

9

12

26

50

19

12

31

36

1 Based on 100 trees of each species in each spacing, or a

total of 1,600 trees per species.

SEASON OF TRANSPLAJVTING

Transplanting is invariably done in the spring in

the Prairie-Plains. Fall transplanting has been tried,

Species

Juniper:

Eastern redcedar

Do

Rocky Mountain

Do

Pines:

Austrian

Jack

Ponderosa

Do

Red

Spruce:

Blue

White

Do

Average loss

Percent

4.4

12.5

11.5

15.2

10.1

14.9

12.4

7.4

11.1

6.1

8.7

11.4

but its use generally resulted in abnormally high losses,

especially in the Northern Plains.

Trees should be transplanted as early in the season

as possible to take maximum advantage of the growing season, especially when the trees are left in the

transplant bed only 1 year. In the Dakotas, some

transplanting has been done in late May and early

June and has been successful, especially in producing

ponderosa pine and juniper stock that was rather well

balanced as 2-2 stock. It could more accurately be

described as 2-1/2 stock since it had only about I/2

growing seasons in the transplant bed.

TOP AND ROOT PRUNING

Top and root pruning are used in Prairie-Plains

nurseries to retard excessive top growth and keep the

trees in better balance. Some favorable results have

been obtained, but there is insufficient information on

which to make general recommendations. Root pruning of seedlings and transplants is also done in the

beds prior to lifting as a preparation for transplanting

or packing.

The survival of blue spruce of 2-2 or 3-2 age class

undercut in the third week of April in the transplanting bed was 18 percent greater (range 4 to 27 percent)

than that of unpruned stock.^^ ^j^^ first-year field

survival of the undercut stands was 94 to 100 percent

Ponderosa pine of 2-2 age undercut in the same series

of tests had a survival of 100 percent, while the unpruned stock had a survival of 94 percent.

Undercutting of third-year Rocky Mountain juniper m the spring at Towner Nursery in North Dakota

slightly improved the balance. Fairiy fibrous root sys-

^ Personal communication with E. J. Georee Agricultural

Re^search Service Field Station, Mandan, N.^Dak^^^£ 2!

tems resulted from a strong stimulation in lateral

rooting. Practically no roots formed at the point of

root pruning.

To cut nursery production costs, root pruning of

seedling stock in place has been recommended as a

substitute for transplanting in areas of better rainfall

(Foster 1932, Hastings 1923), but it has not been

tested very much in the drier Prairie-Plains area. A

special thin-bladed root pruner (Olson 1930, Stoeckeler and Jones 1957) or a lifter with the kicker prongs

removed is used. Seedbeds are sometimes root pruned

with a horizontal V-shaped steel blade. Bed margins

bordering paths have been vertically pruned with 18-

inch rolling coulters in drill-sown seedbeds in-early

June (CliflFord 1956a). Two weeks later the entire

bed was undercut by horizontal pruning.

At the Towner Nursery in North Dakota, top

pruning of 3-0 ponderosa pine in June, while the new

growth was still in a succulent stage, had an adverse

effect. The unpruned trees had a first-year field survival of 49.2 percent, whereas that of the top-pruned

trees was only 34.5 percent. A liquid fertilizer was

applied to the trees in this test within a week or so after
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLADÍS

pruning, a procedure found desirable in later top and

root pruning experiments in the Lake States (Stoeckeler and Jones 1957).

Junipers seem more amenable to top pruning than

pines. Rather substantial improvement in balance

was obtained by top pruning 2-2 Rocky Mountain

juniper at the Towner Nursery ( table 12). The reduction of excessive top length by top pruning may

41

improve the balance of juniper. But more specific

mformation on the effects on field survival is needed

before top pruning can be generally recommended for

2-2 Rocky Mountain juniper.

If this species becomes too large at the 2-2 age, as

it does in some nurseries in the Dakotas, an alternative

maybe to grow 2-1 stock, assuming it gives high field

survivals.

TABLE 12.—Eßect of three degrees of top pruning on size and top-root weight ratio of 2-2 Rocky Mountain

juniper

Degree of top pruning

None. .

Light. .

Severe.

Average

length of

top just after

pruning

Inches

8.26

4.06

Measurements of 2-2 stock in fall

Length

Top

Inches

14.0

11. 3

6.0

Root

Inches

10.6

10.4

10.9

Stem diameter

64ths

inch

13.8

12.7

14.3

Fresh weight per tree

Top

Grams

29. 41

22.53

17. 19

Root

Grams

8. 87

8.38

8.25

Total

Grams

38.28

30.91

25.44

Top-root

ratio

3.32

2.69

2.08

HARDENING-OFF

The hardening-off process prepares conifer stock for

survival through the winter. It results from gradual

exposure to temperatures that are about 32° F. (Harvey 1930, Levitt 1956). Physiological changes that

increase cell sap concentration and reduce the succulence of young foliage protect the plants against

sudden drops in temperature in late fall and from

unseasonably warm winds in February and March.

Hardening-off is encouraged by the reduction of the

water supply and the removal of shade.

The cutting off or reduction of the water supply

begins in late August in the Dakotas and in late September in the Southern Plains. Watering should be

kept moderately low for 4 to 6 weeks thereafter. Excessive dryness, however, should be avoided. Sandy

soils should not be allowed to dry below about 2 or

3 percent of available moisture.

Exposure to high light intensity accentuates the

color change in eastern redcedar; color change is generally regarded as a visual criterion of hardening and

formation of anthocyanins (McDermott and Fletcher

1955). The removal of half-shades will accentuate

and advance fall coloration (fig. 33).

Certain species and age classes, notably 1-0 ponderosa pine, 1-0 and 2-0 jack pine, 1-0 Scotch pine,

1-0 lodgepole pine, and 1-0 eastern redcedar, have a

marked color change in the fall—from green to purple, violet, or bronze (Busse 1930, Dengler 1944,

Kalela 1937, Kienitz 1922, Langlet 1936, Stoeckeler

and Rudolf 1956). The color change, part of the normal hardening-off process, occurs from late September

to early November, depending on the nursery location.

It is especially striking in pine nursery stock grown

from seed of colder or more northern latitudes

(Stoeckeler and Jones 1957) than that of stock grown

from seed of warmer or more southern areas. In one

F-475I07

FIGURE 33 —Half-shade is rolled up in early September and

left in paths until late October to harden-off the stock.

It is then replaced to give overwinter protection. Towner

Nursery, Towner, N. Dak.
42 AGRICULTURE HANDBOOK 2 79, U.S. DEFT. OF AGRICULTURE

study the degree of color change in jack pine showed a

statistically high correlation with latitude and average

January temperature of the seed source (Stoeckeler

and Rudolf 1956). The abnormal color disappears

during the next growing season, with little apparent

effect on the plant.

DIGGING, GRADING, PACKING, STORING, AND SHIPPING

When nursery stock is ready to be outplanted or

sold, its value is a result of all the direct and indirect

costs that have accrued during the time required to

produce it. Therefore, the digging, grading, and

packing of trees must be supervised closely to assure

healthy, uninjured stock when it is fieldplanted. In

addition, the rapid completion of these operations permits earlier shipments to planters and an earlier resumption of other seasonal nursery operations. Some

storage of the packed stock is inevitable, and facilities

must be provided.

DIGGING NURSERY STOCK

Nursery stock lifters are of two general types (fig.

34). One type can be applied to the entire width

of the bed at one time. It may be used for seedbeds

or transplants. The lifter blade for undercutting a

bed may be mounted on a sled or attached directly to

the tractor. A lifter mounted hydraulically to the

tractor is readily transported from place to place. The

second type of lifter is the U-shaped digger used for

transplants in rows. It is usually mounted in pairs

on a Unicarrier frame.

Several elaborate lifter designs have appeared in recent years. These include ( 1 ) the agitating lifter of

the Savenac Nursery, designed to remove some of the

soil from the roots (Sowash 1954), (2) the Lanquist

seedling harvester, which includes an endless belt on

the lifter onto which counted trees are dropped in

bundles (Lanquist 1954a), (3) a hydraulically operated lifter mounted on the back of a crawler tractor

(Cossitt 1937), and (4) a modified two-row potato

digger devised by CliflFord (1956b) for lifting 2-0,

3-0, and 2-2 stock.

At the Bessey Nursery, production of an eight-man

crew is 250,000 seedlings in an 8-hour day; four men

pull, one packs, two carry trees to the baler, and one

works on the tractor lifter. A foreman directs the

operation.^'

A day or two before lifting, beds should be watered.

Watering reduces root breakage and rapid drying of

the undercut beds or rows. The bed-type of lifter is

generally dug in at the end of the bed before the power

is applied. The lifter is run at a depth of about 7

inches for stock to be transplanted and at about 9

inches for stock to be fieldplanted. As the seedlings or

transplants are loosened by the digger, the labor crews

pull the trees upward in bunches and shake the roots

to remove surplus soil (fig. 35). Stock should be

" Personal communication with M. K. Meines, Nursery

Supermtendent, Bessey Nursery, Halsey, Nebr.

grasped well down around the stems and in small

enough bunches to avoid injuring or stripping the

needles and roots.

The importance of exposing roots of trees as little

as possible has been repeatedly emphasized (Briggs

1939, Cummings 1942, Haasis 1914, Stoeckeler and

Jones 1957, Toumey and Korstian 1942, Wakeley

1954). Conifers are particularly sensitive, and as little as 5 minutes' exposure of Jeffrey pine has reduced

field survival by 10 percent, and 10 minutes' exposure

by 15 percent. Every 10-minute period thereafter,

field survival was reduced by about 10 percent. At

F-48891t, 475080

FIGURE 34.—Two types of tree lifters: A, Details of the Bessey Nursery seedling digger revised from the Smith tree

lifter and used for 4-foot-wide beds. B, a two-row lifter

mounted on a Unicarrier chassis, used for transplants lined

out in long rows. Note burlap wrapping to reduce skinning of trees.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 43

FIGURE 35.—Lifting 1—1 ponderosa pine transplants with a Smith tree lifter, Bessey Nursery,

Halsey, Nebr.

the end of 50 minutes of root exposure, field survival

was only about 15 percent (U.S. Forest Serv. Calif.

Forest Expt. Sta. 1954). The rate of air movement,

temperature, and relative humidity are important factors in the rate of root drying and subsequent damage.

Hence, trees should be placed in boxes covered with

wet burlap as promptly as possible and immediately

transported to the grading and packing shed or shelter,

to cold storage, or to crews doing transplanting.

Undercut beds tend to dry out fast, and trees should

not be undercut more than a few hours before pulling.

Work should be planned so that a minimum of unpuUed undercut beds are left overnight or over the

weekend. A light watering of the unpulled undercut

beds with the overhead system may be desirable.

Watering must not be so heavy as to cause substantial

settling and repacking of the soil, or the pulling will

be harder and more roots may be stripped.

Tree digging should be done as early in the spring as

possible, while the trees are still reasonably dormant.

A study at the Bessey Nursery in 1939 on the effect of

early versus late lifting of ea.stern redcedar on first-year

survival showed the serious disadvantage of late lifting :

Survival of

all trees

March 31

April 28.,

Date of lifting Perce-ni

74

33

Survival of

thrifty trees

Percent

57

22

'All trees were fieldplanted on May 5. Bessey Nursery

1939 Ann. Rpt. y / r

Stock for field shipment is root pruned to a length

of about 8 inches, stock for transplanting to 5 to 6

inches. In some nurseries, root pruning is done just

after lifting and before the trees are placed in carrying boxes or trays. In other nurseries, it is done just

before packing or transplanting. Pruning is done

with a circular saw, meat cleaver, modified cleaver

(Mony 1941 ), or a one-blade shear-type pruner with a

stationary base similar to a paper trimmer (fig. 36).

GRADING

Grading nursery stock increases field survival and

growth. It is especially important that the stock

planted meets the grade specificadons in areas where

tree establishment is difficult to obtain. All nursery

stock requires some grading to remove undersized and

defective trees. This is done at die time of transplanting and when stock suitable for fieldplantmg is lifted

for shipment. Gulls at the time of transplanting run

about 10 to 15 percent. Discarded are the obvious

runts; root-stripped, spüt, or skinned seedings; and

diseased or insect-infested trees. Topheavy and oversized trees are also undesirable. In the grading operation, species mixtures resulting from mixed lots ol

seed can be separated.

Grading to remove undersized and damaged trees

has consistently resulted in better survival and growth

in the field (Dejarnette 1938, Powells 1953, Read

1955).
44 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

;-: ^vli

F-502401

FIGURE 36.—The Savenac root trimmer in operation.

As early as 1910, Bates (1910) planted three grades

of 2-1 ponderosa pine on the Nebraska National

Forest and found first-year survival in the field to be

86, 73, and 65 percent, respectively, for large, medium,

and small grades of stock.

In 1935, fieldplanting of 2-0 ponderosa pine of two

size classes, made in 18-inch furrows on Valentine sand

at the Denbigh Field Station near Denbigh, N. Dak.,

resulted in greater survival and height growth for

large-grade stock. Of the 6,132 trees planted, 969

were of the small grade, which consisted of the poorest

of the nursery-run stock. After 10 years in the field

with no cultivation, 21.6 percent of the large-grade

trees and 2.3 percent of the small trees survived. Average total heights were 2.4 and 1.3 feet, respectively.

Fowells (1953) found 10 to 11 percent greater survival of large grades of ponderosa pine after 9 years

in the field. Ninth-year tree heights also were 12 and

18 percent greater for large grades of seedlings and

transplants, respectively.

Undersized trees are culled out largely on the basis

of stem caliper, although top length is sometimes used

as well as root length and development. A caliper

gage (Aamodt 1941, Barton 1940) is useful for trainmg personnel in estimating stem diameter. It may

consist of a Y-shaped piece of brass calibrated in diameter, a notch of a specific diameter cut into a wood

or metal gage, or two pieces of steel welding rod spaced

far enough apart on another rod to provide a fixed

gage.

At the Towner Nursery, cull percent in transplants

has been about as follows : 2-2 Rocky Mountain juniper, 15; 2-2 ponderosa pine, 10; 2-2 white spruce, 10;

and 2-2 blue spruce, 2. In Oklahoma nurseries, cull

percent in 2-0 seedlings of pine and eastern redcedar

intended for fieldplanting is about 10 to 15 percent.

During the grading of stock, it is desirable to reduce

the length of time and severity of conditions under

which tree roots are exposed. Hence, the trees are

generally moved indoors promptly and sorted. Sorting can be done efficiently on an endless belt marked in

squares upon which exactly 10 trees are laid (Robbins

1942 ). Culls are dropped into boxes or onto the floor.

A vegetable spray mist keeps the roots moist while they

are on the 'belt. At the end of the belt, other workers

pick off groups of 5 bunches and tie the stock in bundles

of 50 with an electric bundle tier. Using this system,

8,200 trees can be lifted, graded, and tied per man-day.

PACKING

Trees are wrapped in burlap or waterproof asphaltic

paper prior to shipment. They may be packed in a

baler or rolled tight on a table. Cardboard containers

often are used for parcel post shipments. Some crates

are used.

With the Savenac tree baler (Olson 1930), two wires

are placed in notches across the open end baling box

(34 by 17/2 by 15 inches deep on 20-inch legs), and

two slats (1 by 2 by 24 inches) are laid at right angles

to the wires. A strip of waterproof paper ( 1 /j by 6

feet long) is laid over the wires. Some nurseries use

24-inch-wide burlap. Next, packing material is placed

in a layer about 1 /2 inches deep, and a layer of trees

is laid down, with the roots overlapped and the tops

out toward each end of the baler. A layer of moss is

laid down, and the process is repeated. After the baler

is about half full, some moss is stuffed between the

waterproof paper and trees at the two vertical walls of

the baler so that no roots are in contact with the paper.

When the bale is completed and no roots are exposed, the two ends of the paper are held up and given

enough turns around a third slat to take up all the

slack.

The ends of the wire (Signode straps are sometimes

used) are inserted into a Girard wire-tying machine,

and two ties are made rather tightly to give a firm,

compact bundle that will retain its shape, keep the moss

in place, and not fall apart in subsequent shipment.

Properly packed bales are barrel shaped and are about

18 inches in diameter (fig. 37).

The weight of the bundles and the number of trees

each contains vary by species and age class and the

packing material used. Weights and trees per bale of

some species and age classes for the Bessey Nursery are

hsted below.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAIN'S 45

F-392980, 407442

FIGURE 37.—Two types of containers for shipping

nursery stock: A, A packed bale being secured

with a strapping machine as it lies in the tree baler,

Bessey Nursery, Halsey, Nebr. ; B, crates of the type

used on the shelterbelt project, Towner Nursery,

Towner, N. Dak.

t^eight per Trees per

bale bale

(Pounds) (Number)

83 800

60 2,000

85 645

63 500

60 10,250

88 650

98 2,000

71 4,160

77 1,000

Species Age class

Austrian pine 2-2

Blue spruce 2-1-1

Eastern redcedar 2-2

g° 1-2

p ?°- •• . 1-0 ronderosa pme 2-2

Do 1-2

Do 2-0

Rocky Mountain juniper. . 1-2

In table wrapping, which is better for small orders,

a sheet of waterproof asphaltic paper, about 30 inches

wide and 4 to 8 feet long (depending on bundle size),

IS laid on the table. A 1-inch layer of packing matenal, about 18 inches wide and 24 inches long, is put

on one-half of the sheet near its end, and counted

bundles of trees are placed on the paper, with all roots

overlapped toward the center. Successive layers of

moss and trees are built up until the bundle is full

enough to wrap. A layer of moss completely covers all

trees, and the bundle is rolled as tightly as possible and

tied with binder twine or stout cord in three places.

748-005 O—65 4

In another table wrapping method, all the roots are

placed in one direction on the paper, with the layer of

packing material toward one long edge of the paper.

When rolled, the paper is folded over to enclose the

bottom of the bundle, and tied twice around the circumference and once under the bottom.

Some cardboard boxes are used in parcel post and

express shipments of bare-rooted conifers and potted

grafts. The cardboard box shipments via parcel post

are rather expensive, but the time in transit is minimized.

For Clarke-McNary shipments of stock by the State

Forester in Nebraska, six standard box sizes are used :

Box number Dimensions in inches

lA 4 by 4 by 30.

2 6 by 6 by 30.

3A 4 by 6 by 30.

4 6 by 10 by 30.

5 12 by 12 by 36.

6 10 by 10 by 30.

After assembly with 3-inch gummed paper, the boxes

are lined with wax-coated freezer paper, which comes

in rolls 18, 20, and 24 inches wide. The trees are
46 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

packed wdth well-squeezed sphagnum moss. When

trees are packed with 25 to the bundle, the roots usually

are overlapped in the center of the box and the tops are

out. The packages are then sealed and addressed, and

12 holes are punched in the ends of the long sides near

the tops of the trees for ventilation. Postage, affixed

at the nursery, generally costs about $0.40 per 100 trees,

$0.80 per 200 trees, and $2.00 per 1,000 trees. The

largest boxes can hold about 1,000 trees each of 2-0

eastern redcedar or 2-1 pines, or 400 to 500 trees of 1-2

eastern redcedar.

A few nurseries pack trees in light crates of wood

slats or veneer. Crates are most likely to be useful if

trucks haul the trees from the nursery directly to the

tree-planting site and bring the empty crates back to

the nursery daily or several times a week. In such

instances, the trees need not be counted or tied in

bundles; a bed inventory or a general knowledge of the

average number of trees per crate is a sufficient basis

on which to determine the approximately correct number of trees that should be supplied to field crews or

fieldplanting machines.

Some commercial nurserymen are using plastic film

bags and a small amount of moist moss or peat around

the roots of bare-rooted conifers up to about 2 feet tall.

The method has considerable merit, especially in retail

yards where stock may be held for considerable periods.

The packing materials used for conifers usually are a

50-50 mixture by volume of sphagnum moss and cedar

shingle tow (shavings). The material comes dry in

bales from the supplier and must be mixed and soaked

down before use. Some nurseries keep a vat of prewetted material in a cool, shaded place; it is used to

supply 50-gallon drums alongside the baler or packing

table.

The water in the drums should be cold and should be

cooled with ice if necessary. Warm packing materials

accelerate heating and molding of baled or crated stock

( Stoeckeler and Jones 1957). Usually the water from

deep wells (about 45° to 52° F.) will not require precooling. In some nurseries concrete moss tanks and

slatted drainboards are fitted across the top of the tank.

Excess water must be squeezed out of the packing

material before use, in order to prevent excessive weight

and soggy bundles. It is particularly detrimental in

parcel post shipments made in cardboard boxes.

A detailed study of various packing materials by

Mullins (1956), in which stock was stored up to 4/2

weeks, showed that there was litde to choose between

four materials, based on subsequent field survival.

The materials were commercial sphagnum moss,

freshly collected local sphagnum moss, poplar excelsior

(wood wool), and poplar excelsior treated with a wetting ag^ent.

STORIIVG AND SHIPPING

The interval between lifting and planting should be

mmimized. For example, a prolonged period in

transit and storage between lifting and planting is a

primary cause of poor field survival in shelterbelts.

However, a delay after the trees are lifted from the

nursery bed is not always avoidable. Normal irregularity in planting operations due to weather or other

factors is almost certain to disrupt the flow of stock.

Lifting often must be done before the frost is out of

the ground at the planting site. A more serious problem occurs when the nursery is located far north of

the planting site and lifting cannot begin until some

time after planting is feasible. In some situations storage of planting stock may be necessary for a few days

to several months.

The length of time permissible for storage depends

on temperature, moisture conditions^ packing material,

species, and growing conditions subsequent to planting.

Trees can be stored by three general methods:

Heel-in storage, indoor storage at room temperature,

and cold storage. Great care must be taken to prevent

heating, molding, drying, high transpiration, hardfreezing, and damage by rodents and insects.

Stock in bales, crates, or cardboard containers may

be stored indoors in a ventilated shelter for a few

days (fig. 38). In cool weather, such storage is permissible for about a week. In warmer weather, when

indoor temperatures in the storage shelter reach 70° F.

or above, the trees can be stored in this way for only

a day or two because heating and molding may occur.

Test plantings of 2-0 eastern redcedar in central

and western Oklahoma, conducted to determine the

effect of storage and season of planting on survival,

showed that storage for an extra week in the packages

in which they had arrived from the nursery had little,

if any, effect on survival (Afanasiev et al. 1959).

Plantings were made at four sites at weekly intervals

from mid-November to May during three planting

seasons.

Unbaled conifers have also been stored successfully

indoors for several days to a week on a slat platform

6 to 8 inches above the floor (Engstrom 1941). Oneor two-inch-mesh chicken wire is formed into a cylinder 18 inches in diameter and 4 feet high. A 3-

inch layer of moist moss or other packing material

is laid down, and the trees are placed on top of it,

with the tops out and with the root ends just touching

the wire. Alternate layers of moss and trees are built

up to the height of the v^re form. In warm weather

a block of ice may be dropped on top of a 3-inch-deep

layer of moss inside the chicken wire, and a board

or other cover may be placed on top.

A modification of this system consists of platforms or

racks 24 inches wide, with uprights at each end. Layers of trees are placed with tops out and roots overlapped; enough moss is used to keep the roots moist.

Chipped or chunked ice can be placed on top to provide a cooling effect in warm weather.

At the Northern Great Plains Field Station of the

Agricultural Research Service, at Mandan, N. Dak.,

stock is usually stored on the floor of a root cellar;
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS

FIGURE 38.-Stackecl bales of 2-1 ponderosa pine in storage and ready for shipment by truck, Bessey Nursery, Halsey^Nebr.

individual tree bundles (not bales) are stacked upright m a single layer. Any larger air spaces below the

tops are filled with moist packing material. With this

method, survivals are reported to be 20 to 25 percent

higher than they are with conventionally stacked horizontal storage."

For periods longer than a week, cold storage is necessary. Many nurseries use mechanically refrigerated or

ice-cooled cold-storage buildings. A temperature of

33° to 40° F. is preferred. At this range, respiration

and transpiration are minimized, and heating and

molding are prevented. A temperature of 50° is reasonably satisfactory. The humidity is maintained at

about 90 to 95 percent. An average size cold-storage

plant has a capacity of around 5,000 cubic feet and can

hold 600,000 to 700,000 1-0 or 2-0 trees.

In the Dakotas, stock is often stored on natural ice

m the spring. Partitioned-oflF areas in storage sheds are

Grl^^pT,"^' communication with E. J. George, Northern

MandaS N' SS "' ^^"="''-^' I^««-^^^ Service,

prepared by flooding and freezing during the winter.

The stock is stored in mulch laid on the 4- to 6-inch

layer of ice.

Stock has been held in cold storage for long periods

with little or no drop in field survival (Brown 1937,

DefTenbacher and Wright 1954, Powells and Schubert

1953, Pike 1933, Sowash 1936).

Heel-in storage should be regarded as a last resort

for conifers and should be limited to the spring season. The storage period should not be more than a

week or two; the shorter the time the better. The

trees should be shaded, but a ventilated space of at

least 1 foot above the trees should be provided if canvas

or similar material is used.

In heel-in storage, a straight, broad V-shaped trench

is dug to a depth of 8 to 12 inches, and the well-moistened soil is piled in a ridge at the back. Friable sandy

to silt loam material is preferred. A thin layer of trees

with not more than 1 inch of root-layer thickness is

laid down, and a 2-inch layer of soil is immediately

spaded out and placed on top of the roots. The soil
48 AGRICULTURE HANDBOOK 279, U.S. DEFT. OF AGRICULTURE

F-345374

FIGURE 39.—Heeling-in 1-0 pondero.,a pine, Plumfield Nursery, Fremont, Nebr.

is firmed gently with the bottom of the foot (fig. 39).

Successive layers of trees and soil are added until all

the trees are heeled-in.

The soil must come well above the root collar, but

it should not cover the needles. The layers should be

of uniform depth. A light sprinkling may be done as

heeling-in proceeds or shortly thereafter. Some nurserymen dip the roots of each bundle or handful of

stock in water before heeling-in.

In shipment, larger quantities of planting stock

usually are transported in 1 /a-ton trucks or larger units

such as truck trailers. A 1 /a-ton truck can haul about

60,000 2-2, 90,000 3-0, or 180,000 2-0 trees if they

are crated, and about 50 percent more of each class of

stock if it is packed in bales. Pickup trucks are frequently used to transport smaller quantities of stock

for shorter distances.

State nurseries usually rely on railway express shipments or motor freight for serving customers.

For the usual nonrefrigerated truck shipments, the

chief precaution is a check for temporary load limits

that may have been imposed along the route to be

traveled during or following spring breakup. The

cargo should be well protected against the sun and

wind with tarpaulins. In warm weather, it may be

possible to do most of the trucking at night. Watering

enroute should not be necessary if loads of trees are

properly packed and protected against wind and sun.

When the destination is reached, the stock should be

unloaded immediately in a building, under the shade

of trees, or in a field icehouse constructed for stock

storage.

POTTING AN» BALLING NURSERY STOCK

Conifer nursery stock is potted or balled to increase

field survival on nonirrigated lands in the drier portions

of the Prairie-Plains. Potted stock is used in fieldplanting, whereas the more expensive balled stock is

used most often in ornamental planting.

Ponderosa pine has rather poor root-producing ability (Stone 1955) and rather poor field survival when

planted as bare-rooted stock in a zone from approximately the 101st meridian westward to the Rocky

Mountain area. This zone includes areas in North

Dakota with less than 16 inches of annual rainfall;

areas in Nebraska with 19 inches or less; and areas in

western Oklahoma and northwest Texas with 22

inches or less. This is a zone of high drought frequency (Bates 1935). In farm plantings under these

conditions, consistently satisfactory conifer survival

may be obtained only with potted stock. Potted trees

are also used frequently to replace losses in plantings

made originally with bare-rooted trees. The potting

is usually done a full growing season before fieldplanting.

Potted stock has several advantages that favor high

survival. Practically all the feeder roots are still intact

when planted, whereas unpotted stock often loses some

of these feeder roots when it is lifted. The root system

of potted stock is more compact, has an optimum bond

with the soil, and can continue uninterrupted extraction of moisture at the planting site ; bare-rooted plants

must re-establish this bond by extension of the root

system. The reserve supply of moisture within the pot

is adequate to enable the potted stock to withstand

several weeks of drought, while the bare-rooted plant

is immediately and totally dependent on whatever

moisture it is able to extract from the planting site.

The soil in the pot can be ideally proportioned to stimulate root development and can include substantial

amounts of organic matter to increase the waterholding capacity. The roots or tops of potted stock

are much less likely to heat or mold in transit than

those of bare-rooted stock.

The principal disadvantage of potted trees is the

higher unit cost. Some reasons for this increased cost

are the materials and labor expended in the potting

operation, the need for lathhouses or special structures
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 49

to protect the potted trees during growth and storage,

and the increased transportation costs for distribution

to the planting site.

In western Oklahoma, potted eastern redcedar

planted during 2 years of low precipitation had an

average survival of 96 percent, compared to 70 percent

for bare-rooted stock planted on the same site (Afanasiev et al. 1959). However, the following year both

classes of stock had 94 percent survival.

In tests conducted by the Manhattan Nursery between 1949 and 1953, use of potted stock increased

survival of juniper 15 to 20 percent and that of pine

30 to 40 percent.^^

At the Northern Great Plains Field Station of ARS,

initial survivals of 90 to 100 percent were obtained with

potted ponderosa pine.^^

In western Kansas, the pines and cedars are generally

potted at the 2-0 age in April in 1 y2- by 2/2- by 6-inch

pots and held 1 year before shipment for shelterbelt

planting. The 1-0 eastern redcedar sometimes is large

enough to pot and hold for sale as 1-1.

Since bare-rooted Arizona cypress transplants poorly,

potted stock is fieldplanted almost exclusively in the

Southern Great Plains and the Southwest. It may be

seeded under glass in November in flats of ground-up

sphagnum moss, or in sterilized loamy sand soil. The

seedlings are lifted in March when they are about 3

inches tall, and potted in asphaltic bands or in 2/2-

inch clay pots. Some of the potted seedlings are ready

for fieldplanting the following spring; others are repotted in 1-gallon cans and left for another year.

Potted 16-month-old Arizona cypress ready for fieldplanting will be about 8 inches tall; 1-1 Austrian pine,

4 inches tall; 2-1 Austrian pine, 10 inches tall; 1-1

eastern redcedar, 10 inches tall; and 2-1 eastern redcedar, about 22 inches tall.

Asphaltic roofing paper is one of the materials used

for pots. The method developed by Johnson (Johnson 1955, Johnson and Vanderslice 1956) illustrates its

use. The 36-inch-wide rolls are cut lengthwise into

three 1-foot-wide sections; then each section is cut into

12- by 12-inch sheets. The paper is given four creases

to form a finished pot 23/4 by 23/4 by 103/4 inches and

stapled at the edges five or six times. The bottom

1/2 inches is creased.

A somewhat similar pot of 15-pound roofing felt was

devised by Morris of the Soil Conservation Service and

described by Dovms ( 1954).

Manufacturers produce inexpensive, flat-packed, 15-

pound asphalt-band pots with both ends open. Their

sizes range from 2 by 2 by 6 inches to 3 by 3 by 6 inches.

The 2/2- by 2/2- by 6-inch band contains enough soil

for a 1- or 2-year-old pine or juniper seedling to grow

an additional year and still feed through the standard

'"Personal communication with A. E. Ferber, Soil Conservation Service, Denver, Colo.

"Personal communication with E. J. George, Northern

Great Plains Field Station, Agricultural Research Service,

Mandan, N. Dak.

fieldplanting machines. Such trees occasionally have

been held a second year^ but the pots tend to deteriorate

and fall apart. A 30-pound paper has been better for

trees carried in pots 2 years.

The use of growth promoters such as indoleacetic

acid or vitamin B has resulted in root response on

southern pines (Plank 1939). Fowells (1943), however, found no appreciable response in the number of

secondary roots in ponderosa pine when similar treatments were applied just before the trees were placed

in tar paper pots; however, the length of the root

system was improved slightly.

Shaw (1963) describes a potting system developed

by the Colorado State Forest Service. In this mechanized operation, a series of live conveyor belts is used

to move the potting trays from step to step, and a soil

packing machine is operated by hydraulic pressure.

Other recently developed devices include a hexagonal

soil pot equivalent to a standard 3-inch clay pot and a

potting machine capable of forming 750 pots per manhour; the range in the diameters of the pots is 1.6 to

3.2 inches (Food and Agriculture Organization 1954).

The 2/2- by 2/2- by 6-inch pots can be filled with

soil, and about 750 to 1,000 plants per man-day can be

set in. Tomato lugs (flats) that will hold 30 asphalt

bands are used. A spacer is necessary to keep the pots

open and lined up properly. They are tamped by

jarring the whole flat. The bottom few inches of soil

are tightly packed with a 2- by 2-inch tamper before

the seedHngs are placed in the pot and the pot is filled.

The tamped plug keeps the soil from sliding out of the

bottom of the pots while they are being transferred to

a bed in a lathhouse. The pots when planted weigh

about 2 pounds apiece.

Larger, heavy asphalt pots 6 inches in diameter and

7 inches deep can also be purchased on the open market, as can the 1-, 2-, or 4-gallon metal cans. The

tapered 1-gallon metal pots have distmct advantages

over verrical-walled 1-gallon fruit cans because the

plant and its ball of soil can be more quickly and easi y

removed from them for planting; they are extensively

used in commercial nurseries.

Tapered-steel cylinders have been used for a number

of years at the Agricultural Research Station at Woc^-

ward, Okla.,^^ to lift trees for balling (fig. 40). Ihe

cylinders are I7/2 inches long, are of 18-gage metal

and are about one-fourth to one-half ^ch smaller m

diameter at the bottom than at the top. The following diameters are in use: 6,8, 10 ^^^ ^Vlf H JitT^

When used, the cylinders are forced full depth mto

the soil around the trees. The tree and cyhnde

are then lifted. A clamp is released, the cylinder is

lifted off the soil, and the ball of soil is wrapped m

^"TÏÏ general idea of cylinder balling was adapted to

a commercially manufactured, power-operated ballmg

~^7^X communication with \^J^t'lZÚ:t::iPlains Field Station, Agricultural Researcti öervi ,

ward, Okla.
50 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

FIGURE 40.—Transplanting cylinders with 6-, 8-, 10-, and

16-inch top diameters used to expedite balling of conifers

in sandy soils. Woodward, Okla.

machine. It functions well if soils are medium-textured, free of stones, and have a good soil moisture

content, and if many trees of uniform size can be dug

without frequent change of cylinder size. Balling and

burlapping has been a standard method for handling

larger ornamental stock in the commercial nursery industry for many years (fig. 41).

In recent years, heavy paper, plastic, metal, or other

types of containers, about 8 to 20 inches in diameter,

have found favor in the handling and shipping of

evergreens in the 2- to 5-foot height class.

The potting mixture used in Prairie-Plains commercial nurseries in the 1-gallon or larger containers

is generally about two parts of fertile topsoil, one part

peat moss, and one part sand. In some nurseries onefifth pound of high-analysis commercial fertilizer, such

as ammonium phosphate, per cubic yard, is added. In

other nurseries 1 pound of Milorganite per wheelbarrow of mix is used. In potting Arizona cypress and

pines with top soil that has some alkalinity (pH 7.5 to

7.7), some Southern Plains nurserymen use several

pounds of "sulfa soil" per cubic yard to reduce the

pH and make phosphates and iron more available.

All material is run through a shredder.

In areas where good topsoil is becoming increasingly

more expensive, some nurseries use a 75-25 mixture

of moderately acid fine sand and peat; each cubic yard

is fortified with 6 ounces of potassium nitrate, 4 ounces

of potassium sulphate, 2/2 pounds of ordinary superphosphate, 4/2 pounds of dolomitic hmestone, 1^

pounds of calcium carbonate lime, and 1 '/4 pounds of

gypsum (Matkin and Chandler 1957, Baker et al.

1957). In a supplemental treatment, liquid feeding with nitrogen fertilizers is used ; 1 f>ound of 33 percent ammonium nitrate per 100 gallons of water

(Matkin and Chandler 1957) or a complete N-P-K

(nitrogen, phosphorus, potash) fertilizer is applied.

Details have been published on potting-soil mixtures and their basic ingredients, fortification with dry

fertilizers, use of additional liquid fertilizers, disease

control, and efficient mechanization of all aspects of

the growing of plants in containers (Baker et al.

1957).

F-4751I5

FIGURE 41.—Balling and burlapping blue spruce, Esmond,

N. Dak.

AGE CLASSES OF STOCK NEEDED FOR THE PIAEVS

Both transplants and seedlings are produced for

planting in the Plains. In the North transplants are

used almost exclusively, while in the South seedlings

as well as transplants are used. Good-quality stock is

required. Such stock has a large amount of fibrous

root system and a top about 6 to 12 inches from the

ground line to the tip of the terminal bud (or tip of

cedars) (fig, 42). It should have a thick, sturdy stem

that will hold the plant erect despite wind, clods

thrown against it in cultivation, or the matting-down

action of snow, weeds, or grass.

The age class to which a tree species should be

grown to attain a proper root system, stem caliper, and

height largely depends on the length of the growing

season and the tree species. The level of soil fertility

is another important factor.

The usual age classes of stock by species used in fieldplanting and nursery transplanting under PrairiePlains conditions are given in table 13. Species selection is largely dictated by past performance in survival,

growth, ease of establishment, and relative freedom

from serious pests. State extension foresters, research
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS

FIGURE 42.—Transplant s

Plains planting, grown

background) : A^ Well

juniper.

foresters, horticulturists, and others have prepared

numerous guides and observations on tree species

adaptable to the Plains. Current summaries include

those of George (1953, 1957) and Read (1958).

Stock suitable for transplanting in the nursery is 1 to

i years of age. In the Dakotas, spruces and firs are

grown to a 2-0 or 3-0 age; junipers, redcedars, jack

pine, and Scotch pine to a 2-0 age; and ponderosa

pme to a 2-0 or occasionally 1-0 age before transplanting. From Nebraska south to Texas, eastern redcedar

IS usually transplanted as 1-0 stock, and Rocky Mountain jumper as 1-0 or 2-0. Ponderosa pine is transplanted as 2-0 or 1-0; the former age is more prevalent

m Nebraska.

The influence of increasing age class and the benefits

oí transplanting are illustrated in figure 43.

In northern nurseries it is generally better to grow

the conifers, including ponderosa pine, to the 2-0 age

F-413004, 389090

tock of desirable height, stem caliper, and root development for

at Towner Nursery, Towner, N. Dak. (1-inch squares are in

developed 3-2 blue spruce; B, excellent 2-1 Rocky Mountain

before attempting to transplant them. However, as

soil conditions approach an optimum, fall-sown ponderosa pine and eastern redcedar can be transplanted

as 1-0 stock, even in the northern latitudes with their

shorter growing season.

Seedlings are used for potting. Preferably the trees

should be uniform in size, with 2 to 4 inches of top

(from ground line to tip of terminal bud) for pines,

spruces, and Arizona cypress and 4 to 6 inches for

junipers. This size is generally attained in 2 or 3 years

by spruces, in 2 years by pines, in 1 year by juniper in

the Southern Plains and in 2 years in the Central or

Northern Plains, and in 3 months by Arizona cypress.

The dimensions of typical species and of a number

of age classes vary among nurseries in the Northern,

Central, and Southern Great Plains (tables 14 to 16).

Generally the size of comparable age classes of the same

species increases from north to south.

Well-balanced trees have a rather high proportion

of their total weight in roots. Such plants have a

better chance of survival under the high transpiration

stress of difficult dry planting sites. The top-root ratio

of good transplants generally ranges from 2.0 :1 to

3.5 :1.

In contrast, 2-0 or 3-0 seedlings of somewhat comparable top length have a top-root ratio of 4.0 :1 to

6.0 :1. Moreover, in the seedling stock, a higher proportion of the weight of top is in the needles (a reflection of the size of the transpiration mechanism).
52 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

'i 1- !--io^...-, ;: . vyi-^-;,f

F-3890S9. 413005, 413009

FIGURE 43.—Size and root development of nursery

conifers as aflfected by age class and species, Towner Nursery, Towner, N. Dak. (1-inch squares are

in background) : A, Rocky Mountain juniper, from

left to right, I-O, 2-0, 3-0, and 3-1 ; B, blue spruce,

from left to right, 1-0, 2-0, 3-0, and 3-2; C,

Scotch pine, from left to right, 1-0, 2-0, 3-0, and

3-2.

t- -.*-

ß

4-T 4 .4^^.¿-4..i*A*-w-¿-»-.vit

1

1*^*^"' "'T *--i ■■'■■'»

c ■■

m

:is|í'
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 53

TABLE 13.—Age classes and species of conifers commonly used and being tested in the Prairie-Plains of the

Midwestern United States and nearby Canada

Species

Arborvitae, Oriental

Cypress, Arizona. . .

Douglas-fir ^

Fir:

Balsam 2

Siberian 2

Juniper:

Common 2

Ashe

One-seed

Rocky Mountain

Larch:

European. . . .

Siberizui

Pine:

Austrian

Digger 2

Italian stone 2

Jack

Age

class

1-0

2-0

1-0

2-2

2-2

2-2

2-1

2-0

1-1

2-0

1-1

2-0

1-1

2-1

1-2

2-2

2-1

2-2

2-1

2-2

2-0

1-1

2-1

2-2

1-0

1-1

2-0

1-1

1-1

2-1

Areas where grown

Okla., Tex.

Do.

Okla.,2 Tex.

Canadian Plains, N. Dak.,

S. Dak.

Canadian Plains

Do.

N. Dak., S. Dak., Nebr.

Okla.,2 Tex.

Okla., Tex.

Kans.,2 Okla.,2 Tex.

Kans., Okla., Tex.2

Canadian Plains, Okla.,

Tex.

Okla., Tex.

Canadian Plains,2 N.

Dak., S. Dak.

Kans., Nebr.

N. Dak., S. Dak.

Canadian Plains

D0.2

Canadian Plains, N. Dak.

Canadian Plains,2 N.

Dak.2

Okla., Tex.

Okla.,2 Tex.2

S. Dak., Nebr., Kans.

S. Dak., Nebr.

Okla.

Do.

Do.

Do.

Nebr.

Canadian Plains, N. Dak.,

S. Dak., Nebr.

Species

Pine—Continued

Japanese black

Japanese red . .

Limber 2

Loblolly 2

Lodge pole . . . .

Pinyon 2

Ponderosa

Ponderosa. . . .

Scotch

Shortleaf

Swiss stone 2. .

Redcedar, Eastern,

Spruce :

Blue

Siberian 2

White . . .

Tamarack 2. .

Age

cla^s

2-0

1-1

2-0

1-1

2-1

2-2

1-0

2-1

2-2

2-0

1-1

2-0

1-1

1-2

2-2

2-1

1-2

2-2

1-0

2-2

2-0

1-1

1-2

2-1

2-2

2-2

2-3

3-2

2-2

2-2

2-1

Areas where grown

Okla.

D0.2

Do.

D0.2

Okla., Tex.

N. Dak., S. Dak., Nebr,,

Kans.

Okla.

Canadian Plains 2

Do.

Kans., Okla., Tex.

Do.

Okla., Tex.

Do.

N. Dak., S. Dak., Nebr.,

Kans.

Canadian Plains, N. Dak.,

S. Dak.

Do.

S. Dak., Nsbr., Kans.

Canadian Plains, N. Dak.

Okla., Tex.

Canadian Plains, N. Dak.,

S. Dak.

N. Dak., Nebr., Okla.,

Nebr., Kans., Okla., Tex.

Nebr., Kans.

N. Dak., S. Dak.

S. Dak.

Canadian Plains, N. Dak.,

S. Dak., Nebr., Kans.2

Canadian Plains, N. Dak.

Do.

Do.

Canadian Plains, N. Dak.,

S. Dak., Nebr.

N. Dak.

^ See Appendix for scientific names.

2 Not used extensively, still being tested, or receiving restricted use in areas of better rainfall.

TABLE 14.—Measurements of various age classes of Towner Nursery stock, Towner, N. Dak., fall 1941 and

spring 1958

Age

class Species

Trees per square foot

Trees

measured

Length

Stem diSeedbed Transplant bed

Top Root

ameter

1-0 Eastern redcedar

Number

30

40

40

20

30

Number Number

15

10

10

10

15

Inches

2.9

6.8

5.4

2.9

5.2

Inches

7.2

8.2

9.8

6.5

8.9

64ths inch

3

2-0 do 9

1-1

1-0

do

Rocky Mountain juniper

do

16 8

3

2-0 5

Fresh

weight

per plant

Grams

1

13

10

1

3

Top-root

ratio

based

on green

weight

2.6

2.8

1.8

2.3

2.0
54 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

TABLE li—Measurements of various age classes of Towner Nursery stock, Towner, N. Dak., fall 1941 and

spring 1958—(Continued)

Age

class Species

Trees per square foot

Trees

measured

Length

Stem diameter

Fresh

weight

per plant

Top-root

ratio

Seedbed Transplant bed

Top Root

based on

green

weight

13-0

2-1

Rocky Mountain juniper (Gont.)

do

Number

5

30

50

50

50

40

Number Number

10

10

15

10

10

15

20

10

14

10

20

15

10

10

15

15

15

10

20

15

20

20

15

15

Inches

15.9

7.5

14.0

11.3

6.0

1.6

2.7

6.2

4.4

3.1

4.6

7.6

1.6

2.4

5.0

2.5

7.8

0.7

2.7

4.9

4.4

6.8

6.3

3.6

Inches

11.6

8.3

10.6

10.4

10.9

7.6

8.5

8.6

9.7

8.3

13.3

14.0

4.2

7.8

8.8

7.5

11.2

5.5

7.9

8.2

11.4

18.2

9.2

9.5

64ths in.

25

7

14

13

14

4

6

15

14

10

15

21

2

8

9

6

17

2

4

7

10

17

13

8

Grams

87

7

38

31

25

1

3

20

16

9

23

58

4

5

3

32

«-

2

4

5

26

22

7

4.2

16

16

16

16

2,0

2 2-2 do 3.3

3 2-2 do 3.7

4 2-2 do 2.1

1-0

2-0

2 3-0

6 3-0

1-1

1.4

do 1.5

do 26

13

40

40

30

30

30

30

40

18

73

{')

75

20

6. 1

do •

4.7

do 16

16

2.2

2-1 do 3.7

2-2 do 3.4

1-0

2-0

8 3-0

1.1

do 2.5

do 3.6

9 3-0 do 3.2

2-2 do 16 2.6

1-0

2-0

1.3

do . • 2.2

3-0 do 2.3

2-1 do 1.2

2-2 do 1.9

3-2 do 16 2.3

2-0 T;a/>lr 'ninf* 3.2

1 Low seedbed density. 2 Not top pruned. 3 Top pruned at 8 inches. ^ Top pruned at 4 inches. 5 Top pruned at 4 to 5 inches

0 Data not available. ? Less than 1 gram. « Mycorrhizal soil. ^ Nonmycorrhizal soil.

TABLE 15.—Measurements of various age classes of Bessey Nursery stock, Halsey, Nehr., spring 1958

Age

class

Species

Trees per square foot

Seedbed

Transplant

bed

Length

Top Root

Stem diameter 1

Fresh

weight

per

plant ^

Top-root

ratio

based on

green

weight

2-0

1-1

1-2

1-0

1-2

1-0

2-0

1-1

1-2

2-1

2-2

1-0

2^

2-1

2-2

2-0

2-1

1-0

1-0

2-1

2-1-

Eastern redcedar

do

do

Rocky Mountain juniper.

do

Ponderosa pine

do

....do

do

....do

do

Austrian pine.

do

...do

. .do

Red pine

do

White spruce.

Bfue spruce. . .

do

do

Number

50

Number

17

17

60

50

50

17

17

17

17

17

50

50

60

75

75

17

17

17

17

17

Inches

. 9.2

5.6

12.6

2.3

8.0

1.4

4.0

3.3

5.5

2.9

13.4

1.2

2.7

4.3

12.2

1.4

4.4

.5

.7

3.1

4.5

1 Twenty trees were measured for each combination of species

and age class except blue spruce 2-1-1, for which only 16 trees

were measured.

Inches

14.9

11.7

18.9

5.5

13.6

6.6

12.0

12.5

15.6

11.0

22.0

7.3

11.0

14.2

26.2

11.6

12.5

2.6

3.6

10.1

9.5

64ths inch

16

7

14

2

13

4

14

12

18

12

32

3

6

12

21

7

12

1

1

6

7

Grams

2 Data not available.

3 Weights less than 1 gram.

38

9

26

1

18

2

17

8

27

8

109

1

4

15

75

6

12

2.5

1.5

2.1

2.3

2.5

1.7

1.6

2.0

3.0

1.6

4.1

1.7

1.6

1.5

2.8

.6

1.2

2.0

.5

.8

1.2
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 55

TABLE 16.—Measurements of various age classes of Norman Nursery stock, Norman, Okla., spring 1958

Age

class Species

Trees per

square foot

of seedbed

Length ^

Top Root

Stem diameter 1

Fresh

weight

per plant ^

Top-root

ratio based

on green

weight

Number

1-0

2-0

1-0

2-0

3-0

1-0

2-0

3-0

2-0

3-0

2-0

2-0

Eastern redcedar.

do

Ponderosa pine. .

do

do

Austrian pine...

do

do

Swiss stone pine.

.....do

Digger pine

do

40

40

30

30

30

35

35

35

50

50

10

10

Inches

5.4

17.0

2.4

6.6

12.2

1.9

5.3

10.

16

18

14

15

Inches

10.3

15.8

8.9

13.0

17.0

7.6

12.2

22.3

11. 1

18.2

17.8

17.9

64ihs inch

6

19

6

16

24

3

12

22

16

21

23

23

Grams

5

48

2

21

47

2

14

52

38

55

57

58

3.6

3.6

2.3

3.4

4.2

3.4

2.8

3.4

5.4

3.5

2.9

3.0

1 Twenty trees were measured for each combination of species and age class except digger pine, for which 40 trees were

measured.

INVENTORY

Each nurseryman must know the number of trees,

by species and age class, in his nursery so nursery and

fieldplanting activities can be properly coordinated and

costs of production can be determined. As it is normally impractical to make 100-percent counts, adequate sampling must be employed. Because of the

more rigorous climate, stands of conifers in Plains

nurseries are generally not as uniform as those elsev/here in the country; thus, a larger sample is required

to secure estimates within the required accuracy limits.

Methods needed to obtain the counts are the same as

those necessary in the South (Wakeley 1954) or the

Lake States (Stoeckeler and Jones 1957).

An inventory which considers the causes of variation

in the average stand per square foot of producing area

should be made for each seeding. These variables may

include seed source, age of stock, species, year of seed

collection, season of sowing or transplanting, and other

factors. The cost of this inventory should be only a

few cents per thousand seedlings if the percentage of

sample is properly gaged to the overall totals of the

classes listed above.

For the seedling inventory, it is conamon practice to

make two estimates—one of the total living seedlings

in a nursery block, or unit of it, and another of the

percentage of these seedlings that are plantable. The

accuracy of the final estimate of tree numbers will be

increased if (1) the random or systematic location of

sampling points provides a good cross section of conditions on the entire area; (2) the counts are made

accurately; (3) the grading specifications used to

determine the percentage of seedlings in the sample

that are plantable are the same as will be used at the

time of lifting and shipping; and (4) the person

making the inventory is not biased.

A 4.0- by 0.5-foot strip across the seedbed is a common sampling unit of inventory in the Lake States

(Stoeckeler and Jones 1957) ; a 4- by 1-foot strip is

usually used in Southern nurseries (Wakeley 1954).

More samples can be obtained from the smaller strip

in the same time, and they will yield more accurate

estimates of the total, especially where the beds are

nonuniform.

The area is defined by a frame of wood, steel welding

rods, or flat steel strips reinforced with one or more

crossbars. The frame may be open at one end for ease

of placement on the bed, but it should be rigid enough

to have a constant inside dimension of the sample size

desired.

The number of 4.0- by 0.5-foot sample counts that

can be taken per 8-hour day where seedlings average

about 45 to 50 per square foot is as follows (Stoeckeler

and Tones 1957) : _ .

^ Sample

counts

Class of stock ^"i20-Í60

1-0 : ; : ; : 90-120

?:S : : : : : : : : ; • «^^°^

The intensity of the sample taken will be determined

by the accuracy of the count required, the purpose of

the inventory, and the area and uniformity of stocking of the seedbeds and transplant beds. More samples are required for nonuniform beds or for areas of

seedbeds that are less than 10,000 square feet, assuming that the same degree of accuracy is needed.

A ly^-percent estimate or three counts per hundred

lineal feet of seedbed has been sufficient for areas larger

than 10,000 square feet (2,500 lineal eet) that have a

uniform density. Estimates within 5 percent of the
56 AGRICULTURE HANDBOOK 2 7 9, U.S. DEFT. OF AGRICULTURE

correct total will be obtained in two of three trials.

Many nurserymen use 10 sample counts per 500-foot

bed.

The location of the samples within the beds may be

random or systematic, but it should be determined

prior to sampling. In a systematic layout, samples are

placed at regular intervals in the bed, the distance

between samples depending on the total number to be

taken. The sampling points are located by pacing or

measuring. Counts can be made most advantageously by a two-man crew, one man working on each

side of the bed and counting approximately half of

the bed. To avoid duplication or misses, smaller units

of the area on which the trees are counted can be

marked on the ground or indicated on the sampling

frame.

A prepared form is used to record the counts. The

example shown below has 20 to 25 Hnes per sheet

(Wakeley 1954).

(Name)

Compartment Number

Date of Inventory

Recorder

Measurement started

N E S W end of bed (Circle one)

Nursery Inventory

Length of bed

Species

Seed source

Date sown

Cultural treatment

Uniformity of stocking

Bed number Distance along

bed

Living

seedlings

Plantable

seedlings

Bed number Distance along

bed

Living

seedlings

Plantable

seedlings

(Feet) (Number) (Number) (Feet) (Number) (Number)

Each sample is shown separately; the trees in each

lot are calculated.

The estimate of the number of plantable seedlings is

obtained by digging and counting the plantable seedlings in a subsample of the plots used previously to determine the total number in a unit of the nursery.

These subsamples are selected mechanically at the time

the total inventory is made—for example, by marking

every fourth plot for digging. About 30 subsamples

per unit should be dug. Plot the percent plantable on

cross-section paper over the average number of seedlings per square foot on each subsample. A straight

line drawn through these points gives an estimate of

percent plantable over density for a particular unit of

the nursery. The average density of seedlings per

square foot in the nursery unit is then determined, and

the percent plantable for this density is read from the

graph. This percentage is then applied to the estimated total number of seedlings in the nursery unit to

obtam an estimate of the number plantable. Allowance must be made for seedling growth from the time

of mventory to time of shipment and for mechanical

injury during lifting. The accuracy in making corrections can be improved by careful observation and

study, and the nurseryman should attempt to develop

a set of correction factors for his own nursery.

Because of greater uniformity in transplant beds, less

intensive sampling is required for the same accuracy.

The sampling unit for machine-transplanted trees is

generally a 6-foot-long section of an individual row.

When transplanting is done across the bed with 4-

to 6-foot-long transplant boards, the sampling unit is

the individual row corresponding to the bed width.

In counting transplants a 6-foot-long wooden pole (or

one corresponding to the bed width) with a long, thin

nail or heavy, 4-inch-long wire bent at right angles to

the pole at each end will serve as a sampler.

Where there are about 30 transplants per 6 feet of

row, 160 to 200 samples are counted per 8-hour manday. The percentage of plantable trees in transplant

age classes can be estimated very closely on the basis

of stem caliper and height, so no digging of samples is

required.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS

SOIL MANAGEMENT

57

The problems in selecting a nursery site in the

Plains with the best combination of physical and chemical soil characteristics for conifer production have already been emphasized. Furthermore, since both tops

and roots of the trees grown in the nursery are removed

from the soil, continued high-level production of quality stock requires systematic replacement of the

nutrients.

This section presents soil management practices designed to develop the nursery soil into its highest productive state and to maintain it in that condition.

Major subjects discussed are fertility requirements for

conifer production, determination of nutrient needs by

soil tesdng and visual observation of symptoms of malnutrition, application of chemical and organic fertilizing materials, maintenance of soil acidity at favorable

levels for conifers (pH may change as a result of irrigation), and the great importance of soil inhabiting

organisms such as mycorrhizal fungi to seedling development and their introduction into nursery soils.

Many experiments, replicated 4 to 10 times, were

installed in four nurseries and more than 1,000 beds

in the Dakotas to test soil fertility and pH adjustment.

Randomized blocks, Latin squares, and similar statistical designs were used. In the following discussion

details from a few of these experiments are presented

to illustrate certain effects.

FERTILITY REQUIREMENTS AND THE

DETERMINATION OF NUTRIENT NEEDS

A proper level of soil fertility and physical condition

is a prime essential to good nursery management. The

fertility level is important not only in producing adequate growth but also in imparting frost hardiness

(Kopitke 1941) and drought hardiness (Shirley and

Meuli 1939).

Based on the analysis of the surface 6 to 8 inches of

soil of a number of nursery beds in the Northern Plains

where good seedling growth was observed, adequate

levels of fertility were determined to be as follows

(Stoeckeler and Arneman 1960) :

Total nitrogen (percent) 0. 13

Available nitrogen (pounds per acre of ammonia and nitrate nitrogen) 40.0

Organic matter (percent) 2. 5

Available phosphorus (pounds per acre of

P2O5) 150

Available potash (pounds per acre of K2O)- 250

Cation exchange capacity (milliequivalents

per 100 grams) 12.0

Replaceable calcium (milliequivalents per

100 grams) — 10-5

Replaceable magnesium (milliequivalents per

100 grams) 2.4

Total replacea;ble bases (milliequivalents per

100 grams) ^ 14-2

pH (for juniper species) 6.5-7.5

pH (for ponderosa and Austrian pine)_ 6.0-7.0

pH (for spruces, Scotch pine, and jack

pine) 5. 5-6. 3

Testing procedures are those compiled by Wilde and

Voigt (1955).

Soils of the Plains usually have large calcium, magnesium, and potassium contents. Soils with the recommended texture selected for conifer nursery purposes

are likely to be deficient in phosphorus and occasionally in nitrogen. Some sulfur deficiency is reported

for general farm crops in eastern Nebraska (Jordan

and Reisenauer 1957), and some boron response has

been noted in eastern Nebraska, Kansas, Oklahoma,

and w^estern Texas (Rüssel 1957). Norum et al.

(1957) report for the Northern Plains a general phosphate response, some nitrogen response, and an iron

deficiency in calcareous soils.

The best quick method to determine any shortage

in nutrients is to take 6 to 12 samples from the surface

8 inches of soil of the nursery, keeping the samples separate by past cropping and soil treatment history, soil

texture, and topographic variations, and referenced to

a map of soil type. The soil samples, properly labeled,

can be tested at the agronomy and soils department of

the agricultural colleges, generally on a standard cost

basis. Directions in labeling, packaging, shipping, and

payment will be supplied by these departments or

county agents. In the test, at least the following five

items must be determined: Total nitrogen, available

phosphorus, available potassium, pH, and silt-plusclay content.

The tests for total nitrogen, available phosphorus,

and available potassium, when compared with the fertility table, will usually reveal any serious deficiency.

Because of different extraction methods, soil testing

techniques are likely to indicate different quantities

(in pounds per acre) of available phosphorus and

available potassium. Consequently, it is sufficient that

the contents of both of these nutrients rank as high or

very high, regardless of the method used. Fertilizer

should be applied to remedy shortages. Fertilizer test

plots can be used to verify the need and degree of

response. . .„

The tests for pH should be electrometnc ; they will

reveal actual or potential alkalinity problems and

the amount of acidification, if any, that is needed. 1 he

silt-plus-clay content provides a good general guide,

especially on the first soil tests run on the site, as to its

probable water-retaining ability and cation-exchange

capacity The areas with the lowest silt-plus-clay content are most likely to be low in water-holding capacity, organic matter, and nutrients generally. These

deficient spots may need more manure, peat, compost and commercial fertilizers than do the areas o

K^gher silt-plus-clay content. Differential tr^atmeri

of the nursery areas based on sod fa YSis .^^ l ^^^^^^

in maximum overall benefits from the fertilization.

VISUAL SYMPTOMS OF MALNUTRITION

Soil tests help provide estimates of the Probability of

specific nutrient deficiency, but the nurseryman should
58 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

also use other aids. One is a small-scale test of fertilizer response. A second aid is observation of visual

symptoms of malnutrition such as the vigor and evenness of growth, foHage color, and the length and vigor

of needles and buds.

The chief visual symptoms of malnutrition in

Prairie-Plains conifer nurseries are likely to be ( 1 ) a

yellow chlorotic condition due to immobility of iron in

the plant, probably induced by excess lime carbonate;

(2) a purplish color in spring and midsummer on

spruces and some pines due to phosphate deficiency;

and (3) a patchy, uneven appearance of beds (especially in newly established nurseries) due to lack of

uniform mycorrhizal inoculation, invariably accentuated by phosphate starvation.

When such symptoms of malnutrition are visible, the

trees can sometimes be saved by the treatments described in table 17. In cases of advanced malnutrition, the treatment may not result in any spectacular

cure, and salvaging may have to be limited to usable

stock, or the beds may have to be written off as a total

loss.

In alkaline soils, iron may be immobile. As a remedy, enough acidifying material is added to the soil to

make it moderately acid. This action stimulates a

process known as chelating, which results in mobility

of the iron. The effect of organic matter aids chelating. Special iron chalates, superior to iron sulfate,

have been used in some horticultural crops to correct

the problem, but they have not received much use in

Prairie-Plains nurseries.

TABLE 17.—Symptoms of malnutrition in Prairie-Plains coniferous nursery stock

Deficiency

or excess

Age classes and species

observed

Symptoms and other

detection methods

Treatment required per acre

Mycorrhizae deficiency.

Phosphate deficiency.

Iron deficiency.

Excess alkalinity.

2-0 and 3-0 in jack,

Scotch, and ponderosa pine, and blue

and white spruce.

1-0, 2-0, and 3-0 in

white and blue

spruce.

1-0 and 2-0 in ponderosa and jack pine.

All age classes of ponderosa, Scotch, and

jack pine.

The beds are patchy and uneven.

Mycorrhizal fungi are absent except on trees in patches of good

development.

1-0 and 2-0 stock has a purplish

needle color in late spring and

midsummer; it is sometimes yellowish in 3-0 stock. Needles are short

and may turn brown, terminal

buds are poorly developed, and

lateral buds are weak or absent.

Soil tests may show low available

phosphorus content.

Trees tend to have pale yellowgreen needles. Soil may be alkaline in reaction.

Trees have stunted buds and yellow

or greenish-yellow needles. Soils

may be in a pH range of 7.7 to 8.8.

Work mycorrhizal soil, leaf mold, or

compost into soil, preferably between

drills, and acidify with one-half to 1

ounce of iron sulfate or aluminum

sulfate applied in solution per square

foot. If tests show available phosphate

to be low, apply 600 lbs. of 20-percent

superphosphate or its equivalent per

acre.

Apply 600 to 1,000 pounds of 20-percent

superphosphate per acre or 680

pounds per acre of 11-48-0 ammonium

phosphate.

Use iron chelates or apply iron sulfate

as a foliage spray in a 1-percent solution, wetting needles thoroughly. If

not cured, repeat treatments using up

to one-fourth avd. ounce per square

foot of iron sulfate.

Rake 1}^ avd. ounces of aluminum sulphate per square foot between drills or

rows and water heavily.

The Voorst deficiency problems are often interrelated.

Problems such as excessive alkalinity may result in iron

and phosphate starvation and probably manganese

starvation, and also in spotty distribution of mycorrhizal fungi. Often a drastic lowering of pH results in

a chain-reaction benefit that increases the availability

of three or four nutrient elements, furthers growth of

mycorrhizal fungi, and suppresses certain damping-ofif

and root rot organisms.

Some colors, such as purple, bronze-purple, or violet,

may be misinterpreted. Purpling is the normal fall

color change of some species, especially 1-0 seedlings

of some pine species and eastern redcedar. (See section on hardening-ofT). The degree of color change

is less in the second-year or older pine stock, but it

occurs in older age classes of eastern redcedar. The

purpling due to fall color change persists until late

spring, when it disappears. The purpling due to phosphate deficiency is apparent throughout the growing

season.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 59

FERTILIZER APPMCATIOIVS AND THEIR

RESULTS

To obtain the maximum benefit from fertilizing

materials, nursery soils should be at the optimum pH

level for the species being produced and should be well

supplied with organic matter and mycorrhizal fungi.

The lack of one or more of these requirements may

reduce the effect of fertilization.

A study of response by Rocky Mountain juniper to a

number of organic and chemical fertilizer combinations, with and without acidification, was made at the

Towner Nursery in North Dakota ; each treatment was

replicated 10 times on 4-foot-square subplots (table

18). The nursery soil was a Sioux loamy sand. Size

was not increased because of acidification (treatment

2 ), but there was a strong response in size due to complete commercial fertilizer (treatment 8), to manure

(treatment 7 ), to commercial fertilizer plus peat (treatment 9), and to commercial fertilizer plus manure

(treatment 10). Of the three major fertilizer^, nitrogen gave the most response ( treatment 3 ), phosphorus

some (treatment 4), and potash none (treatment 5).

Only peat gave no response (treatment 6).

Colorado blue spruce reacted quite differently (table

19). Fertilizer alone gave no appreciable response.

The acid treatment alone or in combination with

mycorrhizal soil or Nitrophoska gave the most effect,

doubling the weight of plants but, probably because

of acid injury, lowering the number of trees slightly.

Other spruces, and most pines, tended to respond somewhat similarly to the Colorado blue spruce to acidification and fertilizers. Each treatment was replicated

five times in a Latin square, with 4-foot-square subplots.

TABLE 18.—Effect of fertilization and acidification on 2-0 Juniperus scopulorum at Towner Nursery,

Towner, N, Dak.

Treatment

no.

10

Treatments per unit of area ^

None

Aluminum sulfate, 1 ounce per square foot. .

Ammonium sulfate, 400 pounds per acre

Superphosphate, 800 pounds per acre

Potash, 200 pounds per acre

Towner peat, 20 tons per acre

Sheep manure, 20 tons per acre

Ammonium sulfate, 400 pounds; superphosphate, 800 pounds; potash, 200 pounds

per acre

Ammonium sulfate, 400 pounds; superphosphate, 800 pounds; potash, 200

pounds; Towner peat, 20 tons per acre ;

aluminum sulfate, 1 ounce per square foot. . Nitrophoska, 100 pounds; sheep manure,

20 tons per acre; aluminum sulfate, 1

ounce per square foot

2-0 trees

per square

foot

Number

3.8

3.6

4.0

3.7

4.0

4.3

3.5

4.5

4.3

3.5

Length

Top

Inches

5.6

5.6

6.2

5.9

5.4

5.4

6.5

5.6

6.4

7.5

Root

Inches

9.1

8.7

9.8

9.5

9.2

9.1

9.5

9.2

9.6

9.7

Stem

diameter

64ths inch

8

7

7

9

8

8

9

9

10

Total green

weight per

plant

Grams

7.44

8.21

9.43

8.93

6.95

6.95

10.42

9.20

10.09

13.36

Top-root

ratio based

on weight

2.7

2.7

2.8

2.6

2.8

2.7

2.8

2.7

2.9

3.2

1 All peat was applied on an ovendry weight basis. The

fertilizers used were 20-percent ammonium sulfate, 20-

percent superphosphate, 50-percent muriate of potash, 15-30-

15 Nitrophoska, and ordinary commercial aluminum sultate.

TABLE 19.—Effect of soil amendments on size of 2-0 Colorado blue spruce, Towner Nursery, Towner,

N. Dak.

Treatment per square foot of bed

None

Three-eighths ounce of sulfuric acid (diluted). . .

One-fourth ounce of 15-30-15 Nitrophoska

Three-eighths ounce of sulfuric acid plus 1 pound

of mycorrhizal soil

Three-eighths ounce of sulfuric acid plus onefourth ounce of 15-30-15 Nitrophoska plus 1

pound mycorrhizal soil

Trees per

square foot

at 2-0 age

Number

21.

14.

21.

20.7

18.6

Length

Top

Inches

1.

3.

1.

3.0

2.8

Root

Inches

7.5

7.3

6.6

7.1

7.6

Stem

diameter

64^ths inch

3.3

4.8

3.3

5.2

4.7

Green

weight

per

plant

Grams

0.98

2.12

1.04

2.40

1.99

Top-root

ratio

based on

weight

1.00

1.09

1.00

1.07

1.31
60 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

Nitrogen.—Nitrogen has been applied to the soil at

the time of ground preparation. Application has

usually been at the rate of 40 to 80 pounds per acre,

usually in the form of 20 percent ammonium sulfate

( 200 to 400 pounds per acre ). Sometimes it is apphed

in a complete fertilizer, such as 600 pounds per acre of

15-30-15 or 15-35-15. When applied at moderate

amounts in properly modified soil, adequate stands

were obtained.

Overtreatment with concentrated nitrogen fertilizers

can cause increased damping-ofï or actual chemical

injury and may reduce the tree stand (fig. 44).

Sodium nitrate applied as a preseeding treatment

greatly reduced a stand of 1-0 ponderosa pine. For

treatments of 0, 400, 800, and 1,200 pounds per acre,

the stands per square foot were 54, 31, 20, and 18 seedlings, respectively.

When beds are acidified at the time of fertilization

with nitrogen-supplying materials rototilled ^ into^ the

soil, losses from subsequent damping-off are minimized.

This point is discussed in a succeeding section on maintenance of proper pH.

Phosphorus,—Phosphorus often is the key element in

short supply. When applied at 340 to 680 pounds per

acre of 20-percent superphosphate, it has given good

response. In fact, in some trials as much as 1,320

pounds per acre was used with optimum response.

Phosphorus is also applied in mixed fertilizers. At

most nurseries, use of 600 to 800 pounds per acre of

20 percent superphosphate has been sufficient, even for

the most deficient situations.

Potassium.—If required, about 100 to 200 pounds of

potassium sulphate can be supplied.

H 60

50

a

CL

a

Z40

<

h

<n

o 30

z

-j

o

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- 10

o

^— o

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AMMONIUM SULFATE-POUNDS PER ACRE

FIGURE 44.—This graph shows an example of heavy treatments of nitrogen fertilizers. A small-scale experiment

using 20-percent ammonium sulfate worked into the top

6 inches of soil before seeding on June 9 caused a reduction in 1-0 ponderosa pine tree stand due to damping-ofT

and chemical injury. The beds had not been acid treated.

Stand differences are highly significant statistically.

Towner Nursery, Towner, N. Dak.

Calcium and magnesium.—Csilcium or magnesium

has not been deficient in Prairie-Plains conifer nursery

soils. In fact, an excess has sometimes been a problem.

Iron.—Iron sulfate can be applied as a 1-percent

foliage spray to wet the needles thoroughly in case of

mild chlorosis (Korstian et al. 1921), in amounts of

about 25 pounds per 50 gallons of water per acre

(Imperial Institute of London 1936), or with more

massive doses of 680 pounds or more per acre applied

as a powder at time of seeding or in solution on established beds. Use of iron chelates has definite potential for correcting chlorosis (Haertl 1955, Stewart and

Leonard 1952). For some horticultural crops, application of iron chelates, at 5 to 10 pounds per acre, has

been effective in correcting chlorosis. Often much

heavier treatments are necessary, and the treatment

may be quite costly, especially if 20 or more pounds

should be required per acre. There is little or no

experience regarding the value of chelates on coniferous

nurseries in the Prairie-Plains.

Manganese.—This element can be supplied as a

manganese sulfate powder, disked in before seeding.

In one experiment its application, at 340 pounds per

acre, doubled the ponderosa pine tree stand at the 1-0

and 3-0 stages (apparently due to damping-off control) but did not increase growth. The Imperial Institute of London (1936) mentions its use, at 50 to 100

pounds per acre, as early as 1936.

Useful references on soil fertility include those of the

Chilean Nitrate Educational Bureau, Inc. (1948),

Mayer-Krapoll (1956), Stoeckeler and Ameman

(1960), White and Leaf (1956), and Wilde (1958).

UQ1JID FERTIUZERS AíS TOPDRESSINGS

Liquid fertilizers have been applied as topdressings

in early June on offcolor beds with some success.

Among those that have given good results are ( 1 ) oneeighth ounce of 15-30-15 fertilizer per square foot

applied in June on 2-0 blue spruce (fig. 45) ; (2) onefourth ounce of 11^8-0 ammonium phosphate per

square foot applied in June on 3-0 white spruce; and

(3) one-twelfth to one-eighth ounce of 20-percent

ammonium sulfate per square foot on first- or secondyear pines or spruces. At the Bessey Nursery on 2-0

stock, urea has been found effective when applied m

early June in a dilute solution at 0.042 ounce of urea

per square foot (equivalent to 50 pounds of nitrogen

per acre).

Liquid fertilizers generally are not applied more than

once a year; however, at the Bessey Nursery 2-0 stock

has sometimes received two treatments; each time

0.092 ounce of 20-percent ammonium sulfate per

square foot was used. Regardless of the type of liquid

fertilizer used, overhead irrigation should follow immediately after treatment to wash the fertilizer off the

foliage and prevent fertilizer bum.

Liquid fertilizers can be pumped through the overhead system or applied from an acid barrel. In the
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 61

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FIGURE 45.—Liquid fertilizers can improve the growth and color of the seedlings. These are 3-0 blue

spruce at Towner Nursery, Towner, N. Dak. At left, three trees from an unfertilized bed, at right,

three trees from a bed given a liquid topdressing of one-eighth ounce of 15-30-15 fertilizer ¡jer square

foot of bed in June of the previous season.

latter case, the water-soluble fertilizer is placed in a

sack and hung in the acid barrel to prevent clogging of

the holes in the pipe.

MANURE, COMPOST, LEAF MOLD, AJtO

PEAT

Bulk organic matter has been used with considerable

success in the Plains nurseries. Animal manures are

most often used; however, various composts are also

applied, and development of a peat supply may have

promise in the north.

The chernozemic soils of the Northern Plains are

generally rather well supplied with humus ( NikiforofF

1938), but prolonged cropping gradually depletes it.

Regular application of farm manures in crop rotations

is the best means of reducing the rate of nitrogen depletion (Haas and Evans 1957). The beneficial longrange effect of farm manures has been well documented (Haas and Evans 1957, Salter and Schollenberger 1938, Van Slyke 1932). However, if animal

manures are used, application should be confined to

cover crops or transplants or as an ingredient in compost since their .use may accentuate the damping-off

and weed problems. They should be left in the compost pit for at least 1 year before use in the nursery.

Application of 20 to 40 tons per acre has produced excellent results.

At the ßessey Nursery, until 1953, a compost was

made up of 2,000 pounds of weeds, grass, or other

vegetative material, 25 pounds of ammonium phosphate, and 300 pounds of calcareous clay. The clay

and fertilizer were mixed and layered between the

weeds and kept moist. This material, slightly richer

than barnyard manure, was composted for 2 years

before 20 tons per acre was applied just before the rye

cover crop was plowed under.

In the Southern Plains, higher rainfall intensities,

higher temperatures, and a longer warm season deplete

the humus reserve more rapidly than in the north, and

the use of bulk organic matter (animal manures or

composts) in the nursery becomes even more necessary. Here there is prospect of using straw, and sawdust in the more easteriy areas, as an ingredient in

making composts (Allison and Anderson 1951, Feustel

1938).

Leaf litter has been an excellent material for soil iinprovement in nurseries in forest regions (Lanquist

1945, Wilde 1946). Leaves that have been raked up

from' trees along streets have also been used to advantage (Stoeckeler and Jones 1957). Leaf mold can

sometimes be obtained in the Prairie-Plams from natural stands in bottomlands or hill areas.

Peat deposits with organic matter that can be added

to nursery soils can occasionally be found in the Noithern Plains. These peats tend to have a high pH level.

The range in one bog near Towner, N. Dak., was 6.0

to 7.6, and in most places the pH was about neutral

This peat, when used experimentally at 10, 25, and

50 tons per acre on new seedings of ponderosa pme

748-005 0-65—5
62 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

without acid treatment of the beds, had no deleterious

effect on the tree stand. An application of sheep nnanure, however, drastically reduced the stand from 58

to 22 trees per square foot, and seeding density, from

38 to 14 (fig. 46). The loss was due to damping-off.

80

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MANU

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IRE

D

O 10 20 30 40 50

AMOUNT PER ACRE (TONS)

FIGURE 46.—Comparison of 1-0 stands of ponderosa pine as

affected by two rates of seeding and by the application of

various amounts of moderately acid peat {A and B) and

sheep manure (C and D) to beds just before seeding.

No acid treatment was used. A and C were sown at the

rate of 116 viable seed per square foot. B and D were

sown at 58 viable seed per square foot. The peat treatments had no adverse effect on the stand. The manure

was highly deleterious (at a 1-percent level of significance). Towner Nursery, Towner, N. Dak.

COVER AXD SOIL IMPROVEMENT CROPS

Many Plains nurserymen use a cover crop at least

once every 3 or 4 years in the rotation. Cover crops

have three primary purposes: (1) To prevent soil

blowmg on land not occupied by trees, (2) to add organic matter, and (3) to keep the weed problem reasonably controlled on land without trees.

Cover crops used commonly m the Prairie-Plains

conifer nurseries are Hubam clover, soybeans, biennial

sweetclover, rye, oats, sweetclover, field peas, cowpeas,

and vetch or a rye-vetch mixture. Hubam clover has

been used m the Dakotas, and cowpeas and soybeans in

the Central and Southern Plains.

Cover crops^ that are hosts to various nematodes

should not be used. An example is the soybean cyst

nematode found in States east of the Prairie-Plains

This nematode is difficult to eradicate from infected

fields, and stock from such fields likely would be quarLeguminous cover crops may add as much as 100 to

150 pounds of nitrogen per acre; they also may supply

several tons of organic bulk per acre (Chadwick 1938;

Pieters and McKee 1938; Rogers and Giddens 1957).

Cover crops require some irrigation in dry periods

and may require fertilization. The legumes, particularly, cannot be expected to produce worthwhile crops

without some supplemental water.

Cover crops are plowed under shortly before or

during the first development of flowers, or they may

be mowed at that time so that seed formation can be

avoided and an erosion-preventing mulch can be retained on the surface. Rye is often seeded in late summer in paths and at bed ends as well as on fallow land.

It creates enough cover to give good overwinter protection. All cover crops should be plowed under 4

to 6 weeks in advance of seeding. Many nurserymen

prefer to use them in the rotation before transplanting rather than before seeding.

In North Dakota nurseries, biennial white sweetclover is sometimes sown in May of one year, and

plowed under in May or June of the following year.

In Canadian nurseries, under semiarid conditions,

cover crops such as millet, rye, Sudangrass, and barley

all produced 2 to 4 tons of dry material per acre when

given several inches of irrigation (Knight 1956).

At the Bessey Nursery in Nebraska, the policy is to

use a cover crop every third year. Whippoorwill cowpeas are sown at the rate of 1^ bushels per acre in

early May and plowed under in late July or in the

early blossom stage; the area is left fallow until early

September and then sown to winter rye. Sometimes

rye can be a problem following its incorporation into

the soil because incompletely decomposed plant residues tend to interfere in subsequent seeding or planting. Oats may be superior to rye in this situation.

The amount of organic matter and nitrogen supplied

by a cover crop is rather small compared with that

furnished by the usual 10- to 20-ton treatment per acre

of compost or manure. In many instances excellent

crops of trees have been grown for a prolonged period

without use of a cover crop. For example, at the

Towner Nursery, one tract without cover crops was

used continuously for 10 years and each tree crop was

more vigorous than the previous one. Organic matter in the form of manure was used liberally.

MAINTENANCE OF PROPER pH

The pH of the soil is an expression of its relative

acidity or alkalinity.^^ Many agricultural plants grow

quite well over a wide range of pH, often 5.0 to 8.0,

while others require a soil well supplied wdth lime and

preferably slightly alkaline (Allaway 1957).

^^ A soil with a pH of 3.5 would be considered extremely

acid; about 5.0 to 6.0, moderately acid; 7.0, neutral; 7.5

to 8.0, moderately alkaline; and 8.5 to 9.0, extremely alkaline. Very acid soils are low in lime, while very alkaline

soils (above pH 8.5) have an excess of salts or alkalies which

adversely affects physical characteristics and water relations

of the soil and may depress or kill plant growth.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 63

The maintenance of the proper pH of the soil is very

important in Plains nurseries. Serious errors can

result in extremely high costs per thousand salable trees

or even in stand failure.

Among conifers commonly grown in Prairie-Plains

nurseries, eastern redcedar, Rocky Mountain juniper,

and Siberian larch grow well in circumneutral soils at a

pH of 6.0 to 7.5. Ponderosa and Austrian pines have

done well at a pH of 5.5 to 7.2, and white spruce, blue

spruce, jack pine, and Scotch pine have grown best in a

moderately acid soil of about 5.5 to 6.5.

Broadleaf species generally tolerate more alkalinity

than do conifers (Stoeckeler 1946), and young conifer

seedlings tolerate less than transplants or older stock.

The chief problem encountered in Plains soils is

alkalinity. An inherently high content of carbonates

is accentuated by additional carbonates in irrigation

waters. The problem is more acute if the nursery soil

has poor internal drainage. Often soils that were

slightly acid (6.2 to 6.5) before irrigation have a pH

change to 7.5 to 7.7 after 1 or 2 years' irrigation, with

great subsequent harm to the conifers because of serious damping-ofT, root rot (Davis 1940), and phosphate

and iron starvation. Truog (1946) states that the

availability of phosphorus, iron, manganese, zinc, copper, and boron all are greatly reduced when soil pH is

moderately alkaline. Treating the soil with acidifying

materials such as sulfur may make iron more available

(Holmes and Brown 1957). Bjorkman (1953) noted

potash starvation in spruce on soils with a pH up to

7.6 and reported that mild cases were corrected by

acidification.

Tests of the pH of the top 6 inches of soil should be

made in a number of places to determine the probable

amount of acidification required. Acidification should

not be overdone, and apparently there is no need to

lower the pH below about 5.3 to 5.5 in Plains conifer

nurseries. When the soil acidity is lowered to a pH of

about 3.8 to 4.5, magnesium and calcium deficiencies

may result (Voigt, Stoeckeler, and Wilde 1958).

COMPARISON OF ACIDIFICATION

WITH DIFFERENT CHEMICALS

The alkaHnity of conifer seedbeds cannot be corrected satisfactorily by the usual fertilization practices.

The soil must be acidified. Such treatment will

greatly enhance the effects of fertilizers applied later

and will improve the rate of spread of beneficial mycorrhizal fungi.

To test the efiiectiveness of several chemicals in correcting soil alkalinity by acidification, an experiment

was conducted on a loamy sand soil at the Towner

Nursery in 1938. Seedbeds of ponderosa pine were

treated in the spring at the time of seeding and retested

in the fall of the same year. All chemicals were

applied in solution, using about 1 pint of water per

square foot of seedbed.

Five chemicals (sulfuric and phosphoric acids, and

aluminum, iron, and manganese sulfates) were tested

at three soil depths (figs. 47 and 48).

In the spring of 1938, the top 8 inches of the untreated soil had a pH of 6.8 ; in the fall of the same year,

after one season of irrigation, it was 7.5 for the surface

4 inches and 7.2 for the 4- to 8-inch level. Except for

the weakest solutions, the applications greatly reduced

the pH of the surface 2 inches of soil and somewhat

reduced the 2- to 4-inch and 4- to 8-inch depths.

Considering the vigor and size of seedlings and the

ultimate stand obtained, it was concluded from this

and other tests that a safe, eflPective, and consistent

treatment consisted of application of one-fourth to

three-eighths fluid ounce of sulfuric acid or one-half

avoirdupois ounce of aluminum sulfate per square

foot for a moderately alkaline soil condition. The

degree and persistence of the acidification obtained and

the damaging eflfects on the trees were considered in

this evaluation. For subsequent re-treatment of areas

where previous crops had been acidified^ often oneeighth to one-fourth fluid ounce of sulfuric acid or

one-fourth ounce aluminum sulfate was sufficient.

In addition to the ñve chemicals mentioned, sulfur

in fine powder form was also applied before sowing.

It proved to be ver)^ efiFective at one-fourth to threeeighths ounce per square foot for a first application in

sandy soils and at one-half ounce per square foot on

alkaline silt loams (Stoeckeler and Ameman 1960).

In applying this treatment, any lumps in the material

must be thoroughly pulverized since acid injury may

occur if rootlets of plants contact grains or chunks of

the sulfur. In terms of acidifying power, 7 avoirdupois

ounces of sulfur has about the same eff'ect on pH as 10

fluid ounces of sulfuric acid (Davis, Wright, and

Hartley 1942). .....

Flowers of sulfur tend to produce less acid mjury if

apphed several months or a year before the germination period. However, they have been repeatedly used

in a large number of experiments immediately preceding spring seeding, with no apparent acid injury

and with great benefit to the growth of the more limesensitive tree species. In all cases the material was very

well pulverized and free from grains as large as a

match head.

Sulfur can be expected to be efiFective for a prolonged period. For instance, the effect of a heavy

treatment at the Towner Nursery in 1935 lasted until

the fall of 1941, when some treated areas were still in

the 5.1 to 5.6 pH range. This prolonged effect is due

to the slow chemical reaction and the fact that less

sulfur than sulfuric acid is leached out in imgation

water. . , ^

Some treatments of one-half flmd ounce of concentrated acid per square foot, diluted to about 2 percent in water, have subsequently injured seedhngs.

Therefore, it is recommended that the amount of acid

not exceed three-eighths fluid ounce , , , . ^

Before application, the number of square feet of the

seedbed to be treated is determined. The required
64 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

7.2

7.0

6B

6.6

§«'

6.2

I

a.

6.0

5.8

6.6

54

SULFURIC ACID PHOSPHORIC ACID

h1 1 1

2" DEPTH

yi" PkCDTLJ

)»—-- -"K4-8" DEPTH

: 1

1 ^ >

! ^

\

1

c

N

N

N

N

\

\

N

V

(

<^

\

1 1

! ;

^

^\<x.

\

\

\

\

\

^ 1

\

\

\

V \

\

\,

\

\

\

\^

\

\

>

\

\

_[ I 3 I

8 4 8 2

FLUID OUNCES PER SQUARE

4

FOOT

3

8

i

2

FIGURE 47.—Effect on soil pH of sulfuric acid and phosphoric acid. Applications were

made in the spring of 1938, and the soil tests were made in the fall of the same year.

Towner Nursery, Towner, N. Dak.

amount of concentrated acid is calculated by multiplying the desired dosage (expressed in fluid ounces

per square foot) by the number of square feet. This

amount is then diluted to 2 percent by volume to avoid

injury to the trees. The solution is applied so that all

of the treated area will receive approximately the same

amount.

As noted previously, species vary in their pH preference or their tolerance of alkalinity. The lower dosages (about one-eighth fluid ounce per square foot)

often sufficed for ponderosa pine. Jack and Scotch

pine and all the spruces required the heavier treatnients for best results. At the Towner Nursery, jack

pme beds had eight trees per square foot in untreated

second-year beds (pH about 7.5) while the beds

treated with one-fourth and three-eighths fluid ounce

of sulfuric acid per square foot averaged 30 and 51

trees, respectively (fig. 49). Untreated beds were

chlorotic; treated beds were a healthy green and average heights were double those of the untreated beds

Ihe three-eighths ounce treatment gave the best results at the 2-0 stage.

1/4

SULFURIC AGIO FLUID OUNCES PER SO. FT.

FIGURE 49.—Effect of sulfuric acid treatment of beds at

the time of seeding on resulting stands of jack pine at

1-0 and 2-0 age. The seeding rate was 132 viable seeds

per square foot. The acid was applied in water solution

at the rate of about 25 cubic centimeters of sulfuric acid

per gallon of water. Towner Nursery, Towner, N. Dak.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 65

ALUMINUM SULFATE IRON SULFATE MANGANESE SULFATE

7.6

1 7.4 ^.

7.2

V\

K \

7.0

6.8

— —1

\

1

^

\

V

, \ .A - -*

1A

\

)

/' N

6.6 \N

6.4

6.2

< 4ix;"T-^^ }

- *i I' ^

\

\

\>

1 !

2" DEPTH

6.0 O—— —O 2 4"DEPTH

5.8

5.6

•^ 4-8"DEPTH

1

8

I 3

8

1 0 113 1 0 1

2 8 4 8 2 8

AVOIRDUPOIS OUNCES PER SQUARE FOOT

i

4

1

8

FIGURE 48.—Effect on soil pH of aluminum sulfate, iron sulfate, and manganese sulfate. Applications were made in the

spring of 1938, and soil tests were made in the fall of the same year. Towner Nursery, Towner, N. Dak.

Similar results were observed in blue spruce; with

this species the application of three-eighths fluid ounce

of sulfuric acid per square foot doubled the weight of

second-year trees. In several North Dakota nurseries^

application of one-fourth fluid ounce of sulfuric acid

doubled or tripled the number of usable plants produced per square foot. Results for flowers of sulfur

were similar.

Variable response has been obtained in juniper

seedbeds.

The response to commercial-grade aluminum sulfate also varied by species; ponderosa pine had an

optimum stand when one-half ounce per square foot

was applied ; comparatively greater eflFect was obtained

at higher rather than low sowing rates (fig. 50). In a

trial in which 0, ^2, 1, and 1 /s avoirdupois ounces were

used (fig. 51), the 1-ounce treatment per square foot

gave the best stand of jack pine. The average heights

for 2-0 trees were 1.2, 1.5, 2.0, and 2.0 inches, respectively. Color was not as good as in the sulfuric acid

treatment. In the presence of an adequate phosphate

ALUMINUM SULFATE-AVOP. OUNCES PER SQ.FT.

FIGURE 50—Effect of aluminum sulfate treatment on firstyear ponderosa pine seedbug stands at ^^^ densi les o

seeding. The chemical was raked mto üie top 2 inches

of soil before seeding. Towner Nursery, Towner, N. Dak.
66 AGRICULTURE HANDBOOK 2 79, U.S. DEFT. OF AGRICULTURE

ALUMINUM SULFÍTE - 4VDP OUNCES PER SO FT,

FIGURE 51.—Effect of aluminum sulfate treatment on stand

of jack pine seedlings. The seeding rate was 132 viable

seeds per square foot. The material was applied dry on

newly seeded beds and washed into the soil by heavy

sprinkling immediately after application of the chemical.

Towner Nursery, Towner, N. Dak.

level, on some occasions acidification did not increase

the number of ponderosa pine trees.

Hartley (1915, 1917) did some of the early research

in damping-off control at the Bessey Nursery and other

nurseries. He found a marked increase in tree stand

and size from acid treatment and warned against injury from concentration of acid as the surface soil

dried.

Another important benefit of soil acidification is

weed control. Hartley (1915) reported substantial

weed control by sulfuric, nitric, and hydrochloric

acid. Hartley's results were verified many years later

at the Towner Nursery where the weed stand for a

1-month period after acidification was reduced substantially :

Chemical per square Weed standper

foot

Treatment [ounces)

Control, untreated 0.

Aluminum sulfate J4 avdp. oz,.

Do 1 avdp. oz .

Do 1}^ avdp. oz.

Do 2 avdp. oz . Sulfuric acid J,^ fluid oz . . Do }i fluid oz . .

Do % fluid oz. .

Do ]{ fluid oz . .

square foot

(number)

40

45

37

29

28

40

27

20

13

Acidifying materials such as sulfuric acid or phosphoric acid in about 2 percent solution are generally

applied from an acid barrel immediately after seeding.

A wooden barrel, steel drum, or lead-lined container

drawn by hand or by tractor is used ( fig. 52 ).

F-502095

FIGURE 52.—Application of dilute solution of sulfuric acid

to seedbeds. Bessey Nursery, Halsey, Nebr.

Aluminum sulfate may also be applied in solution

with an acid barrel or cart. Such an application gives

somewhat better damping-off control in the critical

surface inch or two of soil, but it does require slightly

more labor and expense than when the alimiinum

sulfate is applied dry with a fertilizer or lime spreader.

Acidification to maintain proper pH of the soil has

been a common requirement in Plains nurseries. If

soil testing indicates a need for acidification, a safe,

effective, and consistent treatment is the application

of one-fourth to three-eighths fluid ounce of sulfuric

acid or one-half avoirdupois ounce of aluminum sulfate

per square foot for a moderately alkaline soil condition.

CARRYOVER EFFECT OF ACIDIFICATION

Part of the beneficial effect of acidification may last

for more than 3 years. Tests of the soil pH will indicate how much the aftereffect of an initial, rather

heavy acidification has persisted. This will vary

widely, depending on the amount and quality of the

irrigation water used and the tree species involved.

In the fall of 1941, a great variation was observed in

some beds of 3-0 Scotch pine at the Towner Nursery.

These beds were part of an area which, in the spring

of 1936, had been devoted to an experiment involving

various levels of acid treatments including no treatment. The beds were sown to Scotch pine in the

spring of 1939 without any additional soil treatment.

The extreme variation noted in size of the 3-0

Scotch pine in the fall of 1941 was correlated with the
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 67

j

.1'"

FIGURE 53.—Difference in size of 3-0 Scotch pine due to treatment of the soil with sulfuric acid 6 years previously. At

left, three puny nonmycorrhizal seedlings from untreated areas. At right, three large mycorrhizal seedlings from a plot

treated with acid. Towner Nursery, Towner, N. Dak. (One-inch squares are in background.)

acidification treatment of the spring of 1936. The

better and larger trees were in the areas which had

been most heavily acidified, and the poorest trees were

in control beds which had received no acid treatment

in 1936.

Samples of the 3-0 Scotch pine, when examined

after digging, showed a heavy fungus mantle of mycorrhizal development covering the rcxjts of the good trees.

The trees from the areas of poorest development had

few or no mycorrhizal fungi and few or no lateral buds

surrounding the terminal bud. The contrast in the

extremes of the two conditions is shown in figure 53.

Similar and striking benefits from acidification were

observed on ponderosa pine grown on an alkaline silt

loam at Bottineau, N. Dak. ( Stoeckeler and Arneman

1960).

The beneficial effect is attributed to the rapid spread

of mycorrhizal fungi in the acidified beds and to the

improvement in conditions for phosphate and iron

assimilation in the same beds.

THE ROLE OF MYCORRHIZAL FVNGE

Mycorrhizal fungi are organisms that live in association with conifers and some hardwoods (Bergemann

1956, McArdle 1932, Melin 1927, Shemahanova

1957). The mycelia of such fungi are intimately

associated with the living tissues of the roots, permitting

movement of soluble carbohydrates from tree to fungus,

and translocation of mineral nutrients from the fungi

into the tree roots. The end result usually is increased

tree vigor and growth (Wilde 1958).

According to Goss ( 1960), the occurrence of mycorrhizal fungi on pines, chiefly ponderosa, in Nebraska is

relatively sparse in the early spring, compared to their

reported occurrence at this season in the forested areas

of the Eastern United States. However, he found

them on pine roots growing in a wide variety of soils in

field shelterbelts, in the sandy soils of the Nebraska

National Forest at Halsey, and in several nursery soils.

Plains areas or tracts devoid of tree growth for a long

period are likely to have no mycorrhizal fungi (Dale
68 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

and McComb 1955, Goss 1960, McComb 1943, Rosendahl 1942, White 1941). If present, they may be

unevenly distributed. The lack of or incomplete distribution of mycorrhizal fungi has been associated with

early poor development of some of the conifers used

in windbreak planting (fig. 54).

Between 1933 and 1938, an extensive series of experiments with mycorrhizal inoculations and supplementary treatments was conducted at Denbigh, Towner,

Oakes, and Bottineau, N. Dak. It was concluded that

ponderosa pine was favorably affected in some

instances by mycorrhizal fungi, particularly where pH

adjustments had been made by acidification; and that

Scotch and jack pine and blue and white spruces consistently required mycorrhizal inoculation and acidification with sulfuric acid if they were to have good

growth (fig. 55).

Increased growth and lessened chlorosis of ponderosa

pine seedlings resulted from the addition of duff-soil

inoculum to nonmycorrhizal virgin grassland soils

(Goss 1960). More mycorrhizal than nonmycorrhizal

seedlings were able to survive a rapid and extreme soil

moisture deficiency.

Some studies in 1936 included inoculation of beds

with pure cultures or mycorrhizal nursery soil. These

tests demonstrated clearly that the specific mycorrhizal

fungi involved did not thrive in an alkaline soil (pH

about 7.5). However, when the soil was acidified sufficiently to lower pH to 6.0, they grew well.^'

Mycorrhizal fungi can be introduced into prairie

and plains soils by one of several methods:

1. Incorporation of leaf mold, humus, and surface soil (surface 2 to 3 inches) from a wellestablished plantation or shelterbelt of spruce

or pine or from a natural stand.

2. Incorporation of surface soil from a well-established nursery that is free from the more serious

disease and insect pests and has nursery stock

showing an abundance of mycorrhizal fungi.

3. Incorporation of compost made of stockpiled

leaf mold and peat containing mycorrhizal

fungi over the nursery beds.

4. Transplanting some pine or spruce seedlings

obtained from a nursery where the mycorrhizal

fungi on the seedling stock are abundant.

The more successful of these methods has been the

use of mycorrhizal soil or seedlings from natural stands

" The pure cultures were supplied by Dr. K. D. Doak of

the then Bureau of Plant Industry, Washington D C

Wheat was boiled 4 hours and then cooled before inoculation with specific strains of mycorrhizal fungi and other

ë-' /^^^^ spread throughout the glass jar container

within 4 to 6 weeks after inoculation. The species used included: Boletus granulatus, a mycorrhizal fungus found benehcial to certain conifers native to or introduced into the

DiTrh"^ ^""^'* States (including Scotch, eastern white, jack,

pitch, and red pme) ; Ithyphallus ravenelii, a nonmycorrhizal

Dmf"Ld '^' '''°'^'"^ '° ^' °°^'^- ^^' benefited Scotch

iZhh^ , 'P""^"' \"^ ^''' ClUopilus abortivus; and »éredílittí^V.uÍ^''"^"' ^^^'"^'-"' ''^^ '- -°

F-475083, 424671

FIGURE 54.—A, Patchy, uneven condition of second-year untreated beds of ponderosa pine in a North Dakota nursery

caused by uneven distribution of mycorrhizal fungi and

aggravated by soil alkalinity. B, Closeup of mycorrhizal

(right) and nonmycorrhizal (left) seedlings lifted from

gocxl and poor areas in the above nursery. (One-inch

squares are in background.)
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 69

F-397261

FIGURE 55.—Jack pine (2-0) seedlings showing effect of mycorrhizal soil and acidification treatment.

Trees on the right received one-fourth ounce sulfuric acid, 1 pound of mycorrhizal soil, and onefourth ounce of 15-30-15 fertilizer per square foot of seedbed. (One-inch squares are in background.)

or an established nursery, or the use of leaf mold and

surface soil from a shelterbelt of pine or spruce. It

will require at least 1 or 2 bushels of mycorrhizal soil

or leaf mold per 100 square feet of seedbed to obtain

any semblance of uniform inoculation; in order to

use this amount, the material must be kept moist in

transit, an acid soil condition (pH around 6.0) at the

new nursery site must be achieved or maintained, and

the inoculum must be spread very uniformly and disked

into the surface 2 inches, and then the soil must be

watered.

The safest procedure ( the one that will introduce the

least disease and the fewest insect pests) would be to

obtain the leaf mold and surface soil from a natural

pine or spruce stand. However, these are sometimes so

distant that the-material must be obtained from a

planted stand or shelterbelt. If soil that contains mycorrhizal fungi from old nurseries or distant localities

is used to inoculate a new site, it should be clearly free

of insects, diseases, and nematodes. However, moving

of soil or plants from one nursery to another is not generally recommended as a means of transferring mycorrhizal fungi.

The introduction of pure cultures of mycorrhizal

fungi requires more research before it can be recommended for large-scale operations.

Mycorrhizal fungi are capable of maintammg themselves in soils where the host plants are absent for

several years (Rosendahl and Wilde 1942). At the

Towner Nursery, fungi lasted very well without a coniferous host plant from 1943, when the nurîery_ went

out of production, until 1953, when it was reactivated

without reinocultaion of the beds. Even the first crop

of spruce and pine produced after the 10-year lapse

appeared to be abundantly supplied with appropriate

mycorrhizal fungi, and the 2^0 beds in 1954 were quite

uniform and of good color. The presence of humus

extends their ability to survive (Kelley 1930).
70 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

N1JR2SERY PROTECTION

More seedlings are lost or injured from various

causes while in the nursery and during distribution than

later, when they are in the field. To avoid serious

losses from nursery injuries, constant vigilance will be

needed, since early discovery is quite as important as

prompt treatment

Protection of seedlings involves guarding against loss

by four major factors: Weather, insects, mammals and

birds, and diseases. Major sources of injury, as well

as some of the minor ones, are described in this section.

Some formulas for insecticide and fungicide sprays and

for mouse bait are given in the Appendix. Also in the

Appendix, under "Sources of Information on Nursery

Problems," are suggestions on sources from which

additional information on specific problems can be

obtained.

METEOROLOGICAL FACTORS

The climate of the Plains is characterized by extremes. Chief among the characteristics influencing

the production of coniferous stock is the persistent,

rather high wind movement; the low precipitation in

the northwest portion furthest removed from the Gulf

of Mexico ; and the extremely high temperatures which

occur everywhere where moisture is lacking at midsummer. While the nurseryman has no control over

heat, cold, rain, hail, and wind, he can diminish the

effects of all these forces, except hail, by good soil management, timely irrigation, development of effective

windbreaks, and other good nursery practices.

Wind

Wind adversely affects seedling production by ( 1 )

burying the seed and seedlings or blowing them out of

the ground; (2) causing mechanical injury by sweeping along the ground particles of sand that cut the

small seedlings near the ground line or that sandblast

the tender foliage or cotyledons; (3) accelerating depletion of the soil moisture and making the even distribution of water difficult; and (4) intensifying the

drying effect of high temperatures on plant tissue

(Engstrom and Stoeckeler 1941 ). Older stock may be

affected by desiccation of the tops, which results in

foliage and bud damage and a less attractive appearance. Roots dry out faster if the wind is blowing during lifting operations.

The location of nurseries in naturally protected sites

will reduce wind damage. Where this is not possible,

protection must be provided by a system of windbreaks.

For exterior belts, two to seven rows may be needed.

For interior windbreaks, one to three rows should

suffice.

The zone of intensive wind protection for good shelterbelts is usually a15out 10 tree heights. Trees in nurseries with supplemental water and high fertility levels

will generally attain effective heights of 40 to 50 feet.

The spacing between belts thus can be about 400 to

500 feet.

Nurseries with rather limited space may find it

advisable to avoid using cottonwood, Siberian elm, and

other species with widespread root systems. It may be

better to use one to three rows of conifers in exterior

belts and only snow fence for interior portions.

Species that may serve as host or brood trees for

insects and mites or as sources of infection for diseases that attack trees being grown in the nursery

should be avoided if possible. Eastern redcedar has

carried over populations of red spider, with subsequent

reinfestation of new seedlings in Nebraska nurseries;

and white spruce has done the same in North Dakota.

Scale insects and tip moths are examples of insects

that may maintain populations on pine in windbreaks

and thus infest seedling and transplant beds. Phomopsis blight of junipers may be transmitted from older

trees in the nursery to new seedlings.

It is customary to place interior roads next to the

windbreaks as much as possible since, even under irrigation, the 15- to 20-foot zone next to such windbreaks is not suitable for nursery stock production because of the sapping and shading effect of the trees.

Biennial pruning of the roots during the dormant season will help reduce the sapping effect. The pruning

is done 10 to 20 feet from the trees and to a depth of

2 to 2/2 feet. It can be done with a root cutter, a

chisel subsoiler, or a middlebuster plow modified as a

root cutter.

One-row plantings of Siberian elm spaced about 4

feet apart have proved very effective at the Oakes

Nursery (fig. 56). The east-west belts are about 175

to 200 feet apart, and the north-south belts are about

400 feet apart.

The presence of at least one or two rows of conifers,

particularly a row of pine flanked by a row of another

dense-growing species, in exterior or major windbreaks

helps reduce wind erosion when broadleaf species are

devoid of leaves (fig. 57). Nurseries laid out on the

contour may benefit from interior windbreaks paralleling terraces and placed at intervals of about 100 to

200 feet (fig. 58).

Some nurseries use interior hedges of tall-growing

shrubs or trimmed cedar. Some Canadian nurseries

have trimmed hedges of Siberian peashrubs.

Most nurseries use some slat-wire snow fence placed

on pipe supports under pipelines (fig. 59) to reduce

sand movement in the interior of blocks. They are

especially useful on new sites which have little or no

protection by taller tree growth.

The use of annual plants such as sorghum, cane, sunflower, and Sudangrass as temporary windbreaks has

been tried in many nurseries in the Plains region. They

have not been effective in protecting seedlings because

they are not tall enough during the critical period and

they sap soil moisture needed by the seedlings in adjacent rows.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 71

Jf"!

« ^

(PHOTO COURTESY OF THE NORTH DAKOTA STATE SOIL CONSERVATION COMMITTEE)

FIGURE 56.—Siberian elm shelterbelts at Oakes Nursery, Oakes, N. Dak.

Nursery rows should run at right angles to the

prevailing summer wind if the lay of the land permits.

Successive rows of transplants will break up the sweep

of the wind near the ground.

Heat

Extremely high air temperatures damage seedlings

by heating the soil surface at the ground line to a lethal

temperature or by causing the tops to transpire faster

than their moisture supply from the soil can be replenished. The common occurrence of lesions on the stems

of very young seedlings in the Bessey Nursery was early

attributed to excessive heating of the surface soil (Hartley 1918).

Heat injury may appear as heat lesions on the stem

at the ground line or as a burning of the leaves and

succulent tops. Heat cankers have been noted to be

more prevalent on seedlings in rows oriented east and

west.

In Southern Plains nurseries, trees may be damaged

IGURE 57.—This row of 18-year-old ponderosa pine in an

exterior shelterbelt is already a substantially effective wind

Darner both in summer and winter, Towner Nursery,

Towner, N. Dak.
72 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

FIGURE 58.—Interior single-row, 6-year-old hedges at the State Nursery, Norman, Okla. These are mostly oriental aborvitae

(on right) placed on the downhill slope of each terrace. Multiflora rose (on left) and eastern redcedar were used in

a few of the hedges.

F-320779

., , , ."^"'^^ ^•""'=«5 "°t only protect the soil from blowing and the trees from wind injury but also trap snow.

INote relative absence of snow on unprotected field in distance. Towner Nursery, Towner, N. Dak., April 1936.

FIGURE 59.—Slat-
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 73

by heat when hot temperatures and high winds occur in reducing heat losses since seedlings growing close

in May while the plants are still succulent. together protect and shade each other. However,

Shirley ( 1936), in a study of the relative resistance of other factors besides heat protection must be considered

1- to 4-year-old conifers of four species to high lethal before a decision is made on the number of seedlings

temperatures in a water bath and under high (85 per- to be grown per square foot,

cent) and low (15 percent) relative humidities, concluded that: (1) Resistance to excessive heat increases Frost and Winter Bisiir;age

with increasing age and increasing size or mass of plant

and tissue; (2) tops are more resistant than roots; (3) Seedbeds generally need to he protected overwinter,

temperatures as high as 111.7° F., while not causing In the Northern and Central Plains especially, windsevere damage to tops in exposures of up to 5 hours, hurUy winter injury, frost heaving, sudden extreme

may kill the roots; and (4) there is little difference in ^^^^P^ in temperature, and spring and fall frosts are

the ability of red, white, and jack pine and white hazards to the seedlings.

spruce to withstand heat. He also found that the ex- ^^ the North it is risky to have succulent trees in the

ternal killing temperature for plant material of com- nursery later than September 10. Therefore, wellparable size and age was higher in air than in water developed plants must be produced by mid-August in

and higher in dry air than "in moist air. Bates and North Dakota and by September 1 in Nebraska. IrriRoeser (1924), working with ponderosa and lodgepole gation and cultivation should be discontinued at that

pines. Engelmann spruce, and Douglas-fir, also found ^i"^^-

that the resistance of all seedlings to excessive heat Seedling nutrition also is important. Kopitke

became slightly greater with aging and accompanying ( 1941 ) found that a balanced supply of nutrients, and

hardening of tissues and with an increase in the num- especially an adequate amount of potash, appeared to

ber of needles. Older plants stand heat better than t)e the most important prerequisite for the production

first-year trees (Shirley 1936). of frost-resistant stock. Maximum benefits were obBeds of 1-0 ponderosa pine at Towner, N. Dak., were tained when the concentration of potash was adequate

injured when the soil temperature at the surface ^^ produce a vigorous seedling at the very beginning of

reached 120° F. Baker ( 1929 ), in a study of the effect development.^

of unusually high temperatures on coniferous repro- Pines and junipers in the Dakotas are likely to have

auction, found that 1- to 3-month-old seedlings of ^ high percentage of their foliage browned by winter

ponderosa pine and Sitka spruce were quickly killed by injury, even in second-year beds. Sometimes transtemperatures of 130°. plants are affected. The browning is due to loss of

Observations by Roeser (1932) of approximate crit- moisture from the needles while the ground is frozen

ical temperature maxima that ponderosa pine of differ- ^^^ the roots are unable to supply moisture. This

ent ages can endure may be useful to nurserymen in injury may occur in March or early April on bright,

judging whether to irrigate : sunny days with high winds, low humidity, and air

Critical temperature temperatures in the 41° to 60° F. range (Walker and

Age in days in degrees F. Kerr 1954).

^^ 122 Mulches have been used extensively in conifer proI2Q 133 duction in the Plains. Many different materials have

-^^^ been used, including snow fence, shade frames, rolled

He found Douglas-fir and Engelmann spruce were burlap, hay, and plastic sheeting,

more sensitive to heat injury at 71 days of age than A 2- or 3-inch layer of clean straw or marsh hay may

were ponderosa pine or lodgepole pine. be applied shortly before the soil freezes. Coverage

Nursery techniques that will produce sturdy woody should include the paths as well as the seedbeds and

stems as early in the season as possible are a logical transplant beds. The mulch should be left on until

solution to this problem of heat injury. Older seed- March or April.

hngs and transplants shade the soil and reduce the Sawdust is another mulch that has been tried. A

surtace soil temperatures. layer ly^ inches deep was effective in one experiment

Irrigation by overhead sprinklers and shading help (Farnsworth et al. 1956.) Sawdust has been used

reduce the damage from heat. In 1936, considerable extensively only in the Oklahoma nurseries, and there

neat injury was observed on the southwest side of 30- only as a thin covering over recently sown conifers,

to 50-day-old ponderosa pine seedlings at the Towner especially fall-seeded eastern redcedar.

Nursery when the soil surface temperatures reached Paper mulches have been tried experimentally, but

120° F. or higher. On hot days, the high soil surface do not appear to be competitive in cost with other

temperatures, after one-half hour of watering started materials (Robbins 1932).

around noon, were promptly reduced from a critical Snow fence rolled out on the bedboards has given

temperature of about 125° to below 100° and were effective protection. Mulch may or may not be used

held under 120° for 4 hours or longer (fig. 60) (U.S. under it.

Forest Serv. Lake States Forest Expt. Sta. 1937). All beds should be wetted for a few days before

Adequate stand density may be an important factor covering is applied.
74 AGRICULTURE HANDBOOK 2 7 9, U.S. DEFT. OF AGRICULTURE

Woter turned

on I2:l0p.m.

Water turned

Off 1-40 p.m.

C. Soil-surface temp in

sun with no wetting.

90

NOON RM. 2 RM. 3 RM.

TIME OF RECORDINGS

4 RM. 5RM

FIGURE 60.—Effect of watering on soil-surface temperatures: A, Air temperatures in shade; B, soil-surface temperatures in

sun with 1/2 hours of wetting: C, soil-surface temperatures in sun with no wettiner. Towner Nursery, Towner,

N. Dak.

As mentioned earlier, snow fences erected on every

pipeline or on every second line aid in trapping snow

within the nursery and afiford some protection by keeping the trees covered with more snow and for a longer

period in the spring. This practice is especially useful

on transplant beds; however, it does not distribute the

snow as uniformly as is desirable.

Frost heaving is a problem in northern nurseries. It

occurs during open winters with little snow cover and

in early spring when the seedlings are emerging. Often

1-0 stock is frost heaved partly or entirely out of the

ground. Eastern redcedar and spruce are particularly

susceptible. Removing the mulch at a date later than

normal will reduce the damage from this source.

Fall-sown eastern redcedar seed germinates early in

May in central Nebraska. When freezing temperatures may occur after germination, mulching with

clean straw or marsh hay and sprinkling have been

used to prevent frost.

Sometimes after overwinter mulches have been removed in the spring, a severe frost, with temperatures

between 18° and 28° F., may be predicted. The trees

may then be protected by rolling out snow fence on

the bedboards or by rolling burlap directly on top

of the half-shade or directly on top of 1-year-old frostsensitive seedlings such as spruce or fir. Irrigation

with an overhead sprinkler system also offers some protection. The sprinklers are turned on the beds of sensitive species as soon as, or slightly before, the temperature drops to 32° and are kept on until the temperature rises. In some instances a sheet of ice formed

between the trees, but on melting, little or no damage

had occurred from freezing (Stoeckeler and Jones

1957). Most of the efTectiveness of this method in

preventing frost damage is lost when the temperature

reaches below 25°.

NURSERY INSECTS AND MITES

Insects and mites may cause serious damage in nurseries. Frequent checks are necessary to detect injuries in the early stages so that losses are reduced and

control measures can be applied promptly. Damage

may be to the roots or tops or both of seedling and

transplant stock. Some insects, such as white grubs,
COmFER NUBSERr PRACTICE EST THE PRAIRIE-PLAINS 75

are common nursery pests on both conifers and hardwoods in the Plains (Wygant 1936). Others, such as

the Nantucket pine tip moth, attack only conifers and

are found only in certain areas. The range of some

insects is believed to have been increased through the

distribution of i»fested nursery stock (Graighead 1950,

Graham 1939). '

Fortunately, in recent years an improved general

knowledge of insects and their life cycles has made

possible the efficient use of newly developed insecticides. The stomach insecticides are used for killing

top feeders, especially larvae of moths, beetles, and

sawflies. The arsenicals, particularly lead arsenate,

are the most important inorganic stomach insecticides.

Some organic insecticides, such as derris, pyrethrum,

and tobacco products, are stomach poisons. The

newer organic chemicals, such as DDT, chlordane, and

benzene hexachloride, act as both stomach poisons and

contact insecticides. Contact insecticides, which are

used chiefly to control sucking insects, also include

nicotine sulfate, pyrethrum, lime sulfur, sulfur dust,

oils, and oil emulsions.

White Grubs

Larvae of the May beetle and related genera

(Phyllophaga spp.) eat the roots of coniferous seedlings, causing death or reducing growth. Occasionally

the tender stems of newly germinated seedlings are

consumed.

The life cycle of the insect, 2 to 5 years, varies by

species and latitude (Graighead 1950). For the more

injurious species in South Dakota and Nebraska, it is

3 years. The adult beetles eat the foliage of deciduous

trees, and the females oviposit in the soil near the

trees. Most of the damage occurs during the second

year of development, when the grubs are feeding heavily and larval growth is rapid. These larvae are white

and have brown heads, stout, curved bodies, and six

prominent legs.

At the Bessey Nursery in 1930, a grub population

of one to eight per square foot caused losses of as much

as 50 percent of transplant ponderosa pine, with some

damage to jack and red pine. Losses have also occurred in 1-0 eastern redcedar beds. Severe damage to pine transplants reportedly occurred in a nursery in southeastern Manitoba (Prentice and Hildahl

1959).

Before seeding, white grub control can be obtained

in nurseries through the application of 8 pounds of

chlordane per acre. It is applied in the form of 80

pounds of 10-percent dust. The insecticide is mixed

immediately with the soil to an 8-inch depth with a

rotarytiller or disk (Speers and Schmiege 1961). A

mamtenance dosage of 1 to I/2 pounds per acre will

be needed every 2 years. Dieldrin, appHed at the rate

Oí 1/2 pounds per acre and then at one-half pound

every 2 years, may be substituted for chlordane. Excellent control has been reported following fumigation

with methyl bromide gas at the rate of 2 pounds per

lOOsquarefeet (Hill 1955).

Areas with trees receive an application of chlordane

emulsion, applied at a dosage of 1 part in 200 parts

of water, and then sprinkling for 3 to 4 hours to get

the material into the soil. In western Kansas white

grubs in potted evergreens also have been controlled

by application of chlordane.^°

Nantucket Pine Tip Moth

The Nantucket pine tip moth {Rhyacionia frustraría

(Comst.) ) is a pest of most species of two- and threeneedled pines occurring throughout the East and

through the Central States to Texas (Graighead 1950).

A variety {R. frustraría bushnelli (Busck) ) is more

common in the Plains area of Minnesota, the Dakotas,

and Nebraska. The larvae mine the shoots and buds

of nursery stock and older trees. One or two larvae

will hollow out only the buds or apex of the new shoot,

but where they are numerous, the entire shoot may be

riddled with their burrows, and deformation and stuntijig of the trees may result.

The larvae are yellow to pale brown and have brown

heads. They are nearly one-half inch long when fully

grown. Winter is passed in the pupal stage. The

Nantucket pine tip moth pupates within the injured

twig tip, and the form bushnelli, in the litter on the

ground (Graighead 1950), One generation is produced each year in the Black Hills and in North Dakota, two occur in Nebraska (Wygant 1936), and up

to four are produced in Oklahoma and Texas (Afanasiev and Fenton 1947, Graighead 1950).

The form bushnelli has long been a pest at the Bessey

Nursery in Nebraska; infested seedlings were reported

as early as 1911 (Swenk 1927). It was almost certainly introduced to this grassland area on infested

stock (Graham and Baumhofer 1927). Ponderosa

pine is most severely attacked, followed by red, jack,

Scotch, and Austrian pines, in order of decreasing

susceptibility.

In Oklahoma the native shortleaf and loblolly pines

are heavily infested. Also attacked are Japanese red,

Austrian, Scotch, Japanese black, and ponderosa pines,

in descending order of their attractiveness to bushnelli.

The larvae are thought to prefer those species with

thin, soft, flexible needles ( Afanasiev and Ashdown

1951).

The danger of introducing the pine tip moth into

nurseries and plantings on infested stock cannot be

overemphasized. For control of the Nantucket pine

tip moth on planting stock. Hall (1936) recommends

that all seedbeds and transplants be checked in the fall

for evidence of the insect and that all infested tips or

buds be removed and destroyed. Fumigation of stock

moving into or out of the nursery will kill eggs, larvae,

and pupae. A commonly used control measure is to

dip infested stock before shipment in a miscible oil,

alone or mixed with nicotine.

^ Personal communication with Melvin Dimitt, Nurseryman, Garden City, Kans.
76 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

Beds where the insect is present should be sprayed

with DDT.

Red Spiders

Various species of red spiders attack evergreens

growing on the Plains. Nursery stock may become

infested if it is grown close to trees with mite populations. Red spiders are acarinids and not insects but

are considered here because control measures for these

pests are similar to those used against certain insects.

Although small, their number increases rapidly, particularly when the weather is hot and dry. They suck

the juices of plants, causing premature yellowing and

falling of the foliage.

The adults hibernate in the soil or in other protected

places and begin laying their eggs in early summer.

Several generations develop during the summer.

Their irregular webs spun over the leaves and stems of

plants help protect the spiders from wind and rain but

also signal their presence.

The two-spotted spider mite Tetranychus telarius

(L.) is the most common and injurious species (Craighead 1950) ; it has attacked juniper, spruce, and pine in

Plains nurseries. It was particularly troublesome on

juniper species at the Bessey Nursery prior to the

removal of eastern redcedar windbreaks in 1958.

Ponderosa pine seedlings and transplants are also

attacked in this nursery.

The spruce spider mite Oligonychus ununguis (Jacobi) is a pest of ornamental evergreens and coniferous

forest trees and has been reported from North Dakota

(Goodfellow and Colberg 1958) and on the Canadian

prairie (DeGryse 1924). Favorite hosts include Picea,

Juniperus, and Cupressus (Pritchard and Baker 1955).

Nonphosphate acaricides, including aramite, Dimite,

chlorobenzilate,"^ and others, have proven highly effective in controlling infestations. These materials have

the advantage of not being harmful to insects, and the

various species of spider mites apparently have not

acquired immunity to them (Johnson 1958).

The materials are mixed with water and applied at

the recommended dosages from the ground by gardentype or commercial spraying equipment. The foliage

should be wetted thoroughly, and applications should

be repeated when injury is evident or increasing.

Wireworms

Wireworms are long, cylindrical, brown, hardshelled "worms," usually with well-developed legs, that

feed in the soil on small roots and other plant materials.

They are the larvae of the click beetles (Elateridae).

Most species are crop feeders. The roots of newly

germinated seedlings of eastern redcedar have been

attacked at the Bessey Nursery, but damage was slight,

as new roots developed.

^ To avoid using technical nanaes, common names are

given as listed by the Committee on Insecticide Terminology

of the Entomological Society of America for use in the Journal of Economic Entomology. (Haller, H. L., 1957. Common names of insecticides. Jour. Econ. Ent. 50: 226-228)

Plowing, harrowing, disking, and cultivation used

in the nursery for various purposes tend to reduce

populations. Use of soil fumigants such as ethylene

dibromide has given good control of wireworms (Keen

1952).

Cyutworms

Cutworms appear occasionally on conifers in Plains

nurseries; they damage the young trees considerably

by feeding on the foliage, tender roots, or stems, and

by clipping off seedlings at the ground line (Craighead

1950). They are the larvae of night-flying moths of

the family Phalaenidae, commonly referred to as millers. They have been reported in 1-0 seedbeds of the

Monument Nursery in Colorado ^^ and the Savenac

Nursery in Montana.^^ Slight damage has been reported at the Bessey Nursery.^*

Control can be obtained by spreading commercially

prepared baits over the beds in the late afternoon.

Dusts of DDT or chlordane also are effective.

Grasshoppers

Grasshoppers are primarily pests of agricultural

crops, but they may strip the foliage from conifer

nursery stock, particularly during outbreaks and

drought years. Grasshoppers can be controlled with

sprays, dusts, or baits.

Sprays may be composed of one of the following

active ingredients, in the following amounts per acre:

Aldrin, 1^2 to 2 ounces; chlordane, one-half to 1

pound; or Toxaphene, 1 to I/2 pounds (Parker and

Cowan 1953). The lower dosages are used on young

grasshoppers or in areas where the vegetation is short

or sparse. A buffer strip 100 yards wide outside the

nursery as well as the nursery stock should be treated.

Treatment is started when the young grasshoppers

begin to move from their places of hatching.

Other chemicals used in grasshopper control are

methoxychlor, Dieldrin, parathion, and dilan, but these

should not be used unless specifically recommended

by county agents or the State entomologist.

In 1928, in the coniferous plantations adjacent to

the Bessey Nursery, grasshopper damage was heaviest

on Scotch and Austrian pine foliage and stems; in jack

and ponderosa pine, the stems were preferred to the

foliage; ponderosa pines seldom were chewed.^^ No

damage to the junipers was reported.

"^ U.S. Forest Service. 1931 Annual Planting Report, Region 2, Denver, Colo.

^'U.S. Forest Service. 1937 Annual Nursery Report,

Savenac Nursery, Region 1, Missoula, Mont.

''U.S. Forest Service. 1937 and 1951 Fiscal Year Annual Nursery Reports, Bessey Nursery, Region 2, Denver,

Colo.

-^ U.S. Forest Service. Calendar Year 1928 Annual Planting Report, Nebraska National Forest, Region 2, Denver,

Colo.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 77

In 1949, grasshoppers were in the Bessey Nursery,

but they confined their eating mainly to the green

manure crops 26

NURSERY DISEASES

Disease control, according to Hartley (1935a), is

largely a matter of prevention by proper selection of

nursery sites and species and by attention to soil condition, stand density, and sanitation. However, even if

all reasonable precautions are taken, some diseases

are almost certain to be a problem at some time in

every nursery.

Damping-olf

Damping-off is a generalized term applied to the

killing by fungi of very young seedlings just before or

after they emerge from the ground. It is common

throughout Plains nurseries and is the strongest deterrent to the growing of conifers other than the

junipers from seed in this region. Losses from this

cause are sporadic and are slight to complete. Often

this situation introduces great uncertainty into nursery

operations by upsetting stock production schedules,

influencing stand densities, and causing wastage of

seed.

Damping-off affects the seedlings of most conifers;

only the genera Juniperus, Cupressus, Thuja, and

Chamaecyparis are resistant to it (Hartley 1921).

Heavy losses to pine and spruce beds have occurred

in the Canadian prairie provinces, the Dakotas, and

elsewhere. In 1933, at the Bessey Nursery in Nebraska, ponderosa pine sufTered postemergent losses up

to 50 percent, and the red pine was almost completely

destroyed.^^

Hartley (1935a) identified various species of the

genera Pythium, Rhizoctonia, and Fusarium as causal

organisms of damping-off. Pathogenic tests on seeds

of white spruce, blue spruce, Scotch pine, and caragana

at Indian Head, Saskatchewan, showed the same genera but indicated that Rhizoctonia was the most virulent isolate (Cram 1956b). Thomas (1953), in a

preliminary report, suggests that Pythium isolates were

the main cause of damping-off losses in conifers in

Saskatchewan.

To minimize damping-off losses, seedbeds should be

located on sandy soils with good internal drainage.

Heavy or excessively wet soils should be avoided.

Damping-off is increased in severity by the use of

poorly rotted manures, dried blood, or materials that

increase the carbon-nitrogen ratio of the soil (Hartley 1935b). Incorporation of certain cover or soil improvement crops into the soil prior to seeding may

have the same effect. In general, legumes, especially

sweetclover and redclover, increase damping-off. In

*U.S. Forest Service. Fiscal Year 1950 Annual Nursery

Report, Bessey Nursery, Region 2, Denver, Colo.

""U.S. Forest Service. Calendar Year 1933 Annual Nursery Report, Bessey Nursery, Region 2, Denver, Colo.

central Illinois, 64 percent fewer red pine seedlings

were produced in seedbeds where a green manure crop

of cowpeas or soybeans with Sudangrass had been

plowed under while green than in seedbeds with no

cover crop (Wycoff 1952). Fumigating the soil or

removing the crop (instead of plowing it under) are

suggested methods of reducing losses from dampingoff where new seedings follow these crops by necessity at an interval of less than 4 to 6 weeks.

The possibility of damping-off is also increased by

the addition of other materials that decrease' acidity, such as lime, limy sand, wood ashes, or nitrates,

and the use of irrigation water that has a hardness

of over 100 p.p.m. as CaCOa or 125 p.p.m. as a bicarbonate (Davis et al. 1942). Damping-off fungi may

be introduced in infected nursery stock from distant nurseries or in soil brought into the nursery on

machinery.

There are three principal methods of controlling

or reducing the incidence of damping-off. They are

soil acidification, soil sterilization or fumigation, and

the application of fungicides to the seed or soil.

In Plains nurseries, soil acidification is commonly

used since it has the added advantage of counteracting the tendency toward soil alkalinity where alkaline

waters are applied in irrigation. The amount of acidifying material to apply depends largely on soil texture

and its pH before treatment, but it usually consists of

one-sixteenth to one-eighth fluid ounce of concentrated

sulfuric acid per square foot. The acid is diluted in

water to a 2-percent solution by volume. It is appHed

immediately after the seed is sown, and the beds are

then watered. Sulfuric acid has been most effective

in damping-off control of the acidifying materials

tested, including sulfur.

Other materials, such as aluminum sulfate, ferrous sulfate, and phosphoric acid, are also useful

for controlling pre-emergence and ordinary dampingoff loss. At the Bessey Nursery, aluminum sulfate

cost less than ferrous sulfate and produced superior

results. Here, postemergence applications of onehalf ounce of aluminum sulfate in water per square

foot has successfully curbed early summer dampmgoff. Good control has been obtained with an annual

application of 15 grams of aluminum sulfate per

square food of seedbed; it is broadcasted dry and watered in.^^

Deep treatment with one-fourth to one-halt avoirdupois ounce of sulfur per square foot, mixed mto the

soil to a depth of 6 or 8 inches, has value as a dampmgoff control and will lower the pH of the soil for a

longer time than other acidification treatments

(Stoeckeler and Arneman 1960). To avoid acid injury the sulfur should be well pulverized and applied

for several warm months or a full year before seeding.

Fumigating nursery seedbeds with gaseous methyl

bromide reduces damping-off losses. Side benefits m-

- Personal communication with E. W. Johnson Agricultural Research Service Field Station, Woodward, Okla.

748-005 0-65—6
78 AGRICULTURE HANDBOOK 2 79, U.S. DEFT. OF AGRICULTURE

elude the control of weeds, nematodes, insects, and

other soil-borne plant parasites. Standard dosages

for damping-ofif control are 1 to 2 pounds per 100

square feet of soil surface. A machine used at the

Chittenden Nursery, Wellston, Mich., applies the vaporized fumigant rapidly under a polyethylene cover

laid directly over the seedbed (Clifford 1959). Cockerill ( 1957), testing methyl bromide in Ontario, found

that it reduced pre-emergence losses and resulted in

higher emergence of seedlings, but failed to control

later damping-off.

Another means of soil sterilization is the use of onefourth fluid ounce of commercial 40-percent formaldehyde per pint of water per square foot of seedbed.

This solution is applied 7 to 10 days before seeding,

and the soil is then heavily watered (Davis et al. 1942).

Seven days is sufficient in warm weather or on soils

with abundant humus, while 10 days is necessary in

cold, damp weather or on heavier soils.

Pelletizing seed with a fungicide has given better

protection than seed dusts. Furthermore, bird and

animal repellents can be incorporated in the pelletizing

material, and a larger and more uniform seed is produced for sowing. Mony (1958) reported control of

early damping-off at the Vallonia Nursery, Vallonia,

Ind. He used a fungicide-insecticide pelletized mixture consisting of equal parts of 75-percent thiram, 50-

percent captan, and 50-percent W. endrin. He discusses equipment, materials, and methods used in

pelletizing.

In Southern nurseries, seed treatments with fungicidal dusts have given virtually no control of dampingoff of southern pines or other pines (Wakeley 1954).

Soil dusts applied before seeding show promise of

providing more prolonged protection than that secured

with seed dusts. Tests of several soil dusts (Strong

1952 ) indicated that the following were the most promising in Michigan: Thiram (wettable tetramethyl

thiuram disulfide), experimental fungicide 5400, 31

parts of Ceresan M (ethyl mercury p-toluane sulfonanilide) plus 1 part of potassium iodide, and maneb

(manganese ethylene bisdithiocarbamate). These

fungicides were mixed with soil and applied dry with

commercial fertilizers at the rate of 150 pounds of

fungicide per acre. The beds were then rototilled to

a depth of 5 inches. Treatment should be made 3

days before seeding; if rain occurs, seeding should be

postponed for 6 days.

In Saskatchewan, soil drenches with Thiram (75

percent) or captan (75 percent) gave very good control of Rhizoctonia solani without damage to seedlings

in a test on blue spruce, Scotch pine, and caragana

(Gram and Vaartaja 1957). The first application,

made pnor to seeding, was fairly heavy (0.6 gram thiram per square foot) ; later, postemergent light applications were made at 1- or 2-week intervals (0.1 gram).

These materials are particularly useful since they can

be used to control postemergent damping-off in seedbeds where preseeding control measures have been

neglected or proven inadequate.

Indirect methods of controlling damping-off include

sowing at lower seedbed densities, covering the seed

with clean nonalkaline sand, and removing half-shade

or seedbed covers during prolonged damp weather.

Cedar Blight

Cedar blight is the most damaging disease affecting

junipers. It occurs wherever eastern redcedar is produced and has caused heavy losses in Plains nurseries

from North Dakota to Texas. The causal organism,

Phomopsis juniperovora, invades the leaves and small

stems, particularly those of the new growth. The

foliage turns brown and the stem dries out (Baxter

1952). The tips die back and usually the small trees

die. Spores are produced from small, dark fruiting

bodies or pycnidia in the stems and needles of the infected trees. Under moist or humid conditions,

Phomopsis spores are readily disseminated and infect

other plants (Davis et al 1942). Seedlings and transplants are subject to attack throughout the growing

season.

A number of nurseries have been contaminated by

the introduction of blighted cedar as transplants.

There is a little evidence that contamination is possible

by spore dissemination from nearby infected plantings.

The blight in native redcedar in eastern Nebraska was

considered the source of infection in a nearby nursery

(Davis and Latham 1939). Once the disease has been

introduced into a nursery, it is practically impossible to

eradicate, and a continuing program of control is

required as long as junipers are produced. Blight-free

redcedar was produced at the Bessey Nursery for more

than 40 years before the blight appeared in 1956, supposedly from infected planting stock.

Eastern redcedar. Rocky Mountain juniper, and

their horticultural varieties are particularly susceptible,

but other junipers and Arizona cypress are also

attacked. Rocky Mountain junioer has been damaged less than eastern redcedar, probably because of its

slower growth. At Manhattan, Kans., losses of eastern

redcedar during a 3-year period averaged five times

greater than those of Rocky Mountain juniper.^^ In

the Prairie States Forestry Project Nursery at Fremont,

Nebr., Rocky Mountain juniper was much more resistant to blight than eastern redcedar.^^

Caroselli (1957) reported that WK-34 gave good

control of Phomopsis blight when applied at 2- to 3-

week intervals to 1- or 2-year-old seedlings at the rate

of 1.2 ounces per 10 gallons of water. This spray contained 12 p.p.m. of cycloheximide (an antibiotic) and

675 p.p.m. of pentachloronitro benzene.

^ Slagg, G. M., and Wright, Ernest. Phomopsis blight of

eastern redcedar and its control. 1943. Unpublished report on file at the Lincoln Field Station, Lincoln, Nebr.,

Rocky Mountain Forest and Range Expt. Sta., U.S. Forest

Serv., Fort Collins, Colo.

^•^ Personal communication with S. S. Burton, formerly

Woodland Conservationist, Soil Conservation Service, Lincoln, Nebr.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 79

Excellent control has also been obtained by the use

of Puratized Agricultural spray (phenyl mercury compound) at the Oklahoma State Nursery at Norman.

Sprays were applied at weekly intervals or more frequently if needed.

Spraying should be part of the regular nursery operation and should include all seedhngs and transplants.

Sprays should be applied every 7 to 10 days throughout

the growing season. Twice-weekly applications may

be necessary during moist, cool weather (Hodges

1962).

Rusts

Native rust-induced galls are widely distributed on

two- and three-needled pines and to a lesser extent on

junipers. The rusts considered here include only those

fungi that develop on living leaves, stems, or branches

without immediately killing them. Infected planting

stock, however, may die after field planting.

The western gall rust, Peridermium harknessii,

occurs in the West and has been observed in PrairiePlains nurseries (Boyce 1961, Davis et al. 1942).

Ponderosa and lodgepole pines are particularly susceptible. A ball-shaped gall is formed on the stem. The

aeciospores can cause pine-to-pine infection (Meinecke

1929) ; hence, control cannot be effected by eliminating the alternate hosts, which may be paintbrush, lousewort, owlclover, or birdbeak. Infected stock should

be eliminated by grading.

The southern fusiform rust is caused by Cronartium

fusiforme. Limited to the Southern States, it attacks

a number of hard pines, including shortleaf and loblolly. Infected seedhngs have spindle-shaped stem

swellings. Control requires weekly spraying with

ferbam, ziram, or zineb prior to infection (Foster

1959). All seedling tissue must be completely covered.

The eastern gall rust {Cronartium cerebrum) ranges

eastward from the Prairie-Plains and is most abundant

in the Southen States (Boyce 1961). Jack pine and

shordeaf pine are favorite hosts. Oak is the alternate

host. Control measures are similar to those recommended for the southern fusiform rust.

Large transplants or large ornamental stock of eastern redcedar. Rocky Mountain juniper, and other junipers are subject to cedar-apple rust ( Gymnosporangium

juniperi-virginianae). Round galls, 1 or more inches

in diameter, are produced, but damage to the susceptible conifers is usually light. Control is obtained by

spraying the junipers with a general purpose fruit spray

containing ferbam or zineb fungicides at the rate of 1

to 15/2 level tablespoons of wettable powder per gallon

of water. These fungicides should be applied at 7- to

10-day intervals from late July to early September.

Another effective spray is Elgetol, formulated at the

rate of 1 gallon per 100 gallons of water and applied

when the telial horns are small.

Antibiotics show great promise for providing effective control of rust diseases in nurseries, but detailed

application methods are still to be developed.

Nematodes

Nematodes are tiny, threadlike, soil-inhabiting

roundworms that feed on the roots of trees, especially

small seedlings. They weaken the trees and may also

provide entry courts for root rot fungi. The typical

symptoms of nematode injury (Hodges 1962) are a

general decline, stunting, and chlorosis of the seedlings.

The control of nematodes in nurseries is a necessity in

many areas of the country. Their control in PrairiePlains nurseries will assume greater importance when

the damage they cause is recognized and diagnosed

correctly.

The root-lesion nematode has been recovered from

the roots of eastern redcedar at Halsey, Nebr. (Caveness 1957 ), but not from those of ponderosa or Austrian

pine. Stock of 1-0 and 1-1 age class was affected.

After the roots of the 1-0 stock were infected at varying depths, the plants showed slightly offcolor foliage

and reduced growth, and some mortaHty resulted.

The nematodes may be eliminated by treating the

soil with methyl bromide gas at the rate of I/2 to 2

pounds per 100 square feet, ethylene dibromide at

3 to 6 gallons (85 percent EDB) per acre, or chloropicrin at "3 to 5 cubic centimeters per cubic foot of soil

(Munnecke 1957). At the Bessey Nursery use of 1

pound of methyl bromide gas per 100 square feet gave

good control of the root-lesion nematode.^

The manufacturer's directions on the method of

treatment should be followed.

Dieback

Pine twig blight is a dieback of the current season's

growth of hard pines caused by the fungus Diplodia

pinea (Desm.) Kickx. Severe damage to seedlings of

Austrian pine has been reported from a Kansas nursery

by Slagg and Wright (1942). They also reported

(1943) considerable damage from this blight m Southern Plains nurseries on Austrian and ponderosa pines,

pinyon, and Douglas-fir.

Root Rots

The Phymatotrichum root rot has not been reported

from nurseries, but it may become a problem there

since it occurs in Oklahoma, Texas, and other parts

of the Southwest where shelterbelt plantmgs are important Both conifers and hardwoods are attacked,

but eastern redcedar and Rocky Mountam juniper

have a hi-h resistance to the disease (Wright and Wells

1948 ) Based on 6 years of fieldplanting tests m Oklahoma and Texas, ponderosa and loblolly pines were

susceptible and not recommended for use while

Austrian pine was less susceptible and considered capable of surviving on the more sandy soils.

-Personal communication with Glenn llfj^\^^^^;^

Mountain Forest and Range Experiment Station, Lmcoln,

Nebr.
80 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

MAMMALS AND BIRDS

Practically all nurseries are situated so that a fence

is necessary to exclude domestic livestock or the larger

wild animals such as deer. Some nurseries use woven

wire fence or slat-wire snow fence, which will also exclude dogs or even rabbits. The intensity of protection

used will depend entirely on the local situation.

If deer are a problem, a fence at least 10 feet high

is necessary. At the Bessey Nursery extensive damage to seedlings by deer necessitated fencing and later

live trapping when ordinary cattle guards failed to exclude deer at road entrances. In 1945, an estimated

one million jack, Scotch, and Austrian pine seedlings

were nipped and trampled by deer. The preferred

species was eastern redccdar, followed by jack pine.

Rocky Mountain juniper and Austrian pine were

browsed to a lesser extent. Winter cover crops feed

the deer in years of low animal population but attract

additional animals to the nursery.

Jackrabbits, cottontail rabbits, and snowshoe hares

may damage Plains nurseries. It is difficult to maintain a fence high and tight enough to exclude rabbits because they may come in over snowdrifts or get

through under the wire. Occasional checking is necessary to determine whether rabbits have gained entrance and are doing damage by cutting on the tips

of the seedlings. Cover crops may be eaten in preference to trees. If present, rabbits can be eliminated by

snaring, trapping, or shooting.

Pocket gophers [Geomys and Thomomys) occasionally cut tree roots and smother seedlings under

mounds in nurseries. They live almost exclusively in

the ground, pushing out the soil to form troublesome

mounds as they excavate their tunnels 4 to 8 inches

below the surface. Effective controls include the use

of regular pocket gopher traps or the placement of

poisoned bait in the runways. Two or three pieces of

diced fresh carrots or similar vegetable, dusted with

strychnine alkaloid, at the rate of one-fourth ounce

of powder to 4 quarts of carrots, should be put in several places in each burrow system. In replugging the'

placement holes, care should be taken to avoid covering the bait. Pocket gopher control should extend

nearly one-fourth mile beyond the nursery since migration is sometimes extensive.

Many species of white-footed mice {Peromyscus

spp.) may eat the seed of conifers as well as that of

hardwoods. The meadow mouse {Microtus) eats

seeds, and the pine vole {Pitymys), in an area from

eastern Kansas south, may cut off small seedlings.

Kangaroo rats {Dipodomys) have eaten pine seed "in

Nebraska nurseries.

Straw mulches used on seedbeds over the winter

are especially attractive to mice and other rodents.

Populations can be kept down by eliminating weeds

and grass in fence rows. Hardware-cloth screens

placed on bedboards also are used to protect the beds.

Mice can be trapped easily with ordinary snap traps

that are baited with peanut butter, an apple, a vegetable, or oatmeal, and placed in runways or near

entrances of burrows.

The use of poisoned baits is probably the cheapest

and most effective way of eliminating mice and some

of the other seed-eating rodents, such as ground

squirrels.

The principal poisons used are strychnine alkaloid

and zinc phosphide. Poisoned grain may be mixed

with mulch as it is applied to fall-sown beds, or it may

be placed at bait stations at 100-foot intervals. The

stations are staggered somewhat where bedboards tend

to confine and channelize rodent movement. Outside

the nursery, bait should be placed along the fence

and in a bordering zone extending about 200 feet from

the fence. In this zone, especially if it is grassy, bait

should be spaced as close as 30 feet apart, in four lines

paralleling the fence at intervals of about 50 feet.

Commonly the bait is placed in small tin cans laid on

their sides. Thus protected, the bait will remain effective for a longer time, and birds cannot reach it.

Do not place bait where livestock will have access to

it.

Moles damage new seedlings and 1-0 seedbeds by

loosening the ground with their slightly raised runways. The runways also expose the seed or bury it

too deeply. Moles may cut tree roots in a manner

similar to that used by pocket gophers. These animals

must be removed from the seedbeds as well as a small

surrounding area. Mole traps and poison baits are

effective.

Nurserymen with rodent problems may wish to write

to the Fish and Wildlife Service, U.S. Department of

the Interior, Washington, D.C., for the address of the

nearest poison-bait distribution center. Prepared baits

are available at such centers at cost. An alternative

to the purchase of prepared baits is to use one of several

formulas recommended by the Fish and Wildlife Service (Garlough and Spencer 1944) and to prepare the

bait at the nursery. Two poison-bait formulas for mice

are given in the Appendix on page 89.

Seed-eating birds may be a serious problem in conifer

nurseries, particularly in years when the peak of the

spring migration coincides with seedling emergence.

They not only scratch out the seed and eat it, but also

they nip the tops of the seedlings after they have

emerged from the soil but still retain the seedcoats. A

more localized form of damage is debudding of Austrian pine seedlings by sharp-tailed grouse {Pedioecete.s

phasianellus) during the winter.

Birds can be excluded by hardware-cloth screens

placed over all seedbeds or those of the most susceptible species (fig. 61). At the Bessey Nursery fallsown beds of juniper and Austrian pine are screened.

More birds take the smaller seed of Austrian pine than

that of ponderosa pine. Fall-sown juniper beds are

damaged in early spring by the white-crovmed sparrow {Zonotrichia leucophrys).

Repellents such as sublimated anthroquinone are

being applied to seed in Southern nurseries (Mann and
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 81

F-488909

FIGURE 61.—Pettis screen section for seedbed protection

from birds and rodents at Bessey Nurser>', Halsey, Nebr.

Each section is 4/2 by 10 feet; '/¡-inch-mesh netting is used.

Kingsley 1958) and elsewhere (Abbott 1958) to protect seed before and during germination. Anthroquinone with a latex sticker should be applied at the

rate of 15 pounds to 100 pounds of seed. Arasan, another bird repellent being used in Plains nurseries,

also has rodent repellent qualities.

Another method of reducing bird damage is to vary

the time of seed sowing. Fall sowing results in earlier

germination, and in some localities the seedling emergence is completed by the time the main flight of certain species of migratory birds arrives. In other instances, spring sowing may be delayed until the main

offenders have passed on their way north.

Some degree of control may be secured by systematic patrolling of the seedbeds in daylight during the

critical germination period.

Shooting of the birds should be limited strictly to

those species not protected by State or Federal law.

LITERATURE CITED

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1941. Stem caliper gauge for nurseries. Tour. Forestry

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ABBOTT, HERSCHEL G.

1958. Application of avian repellents to eastern white pine

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AFANASIEV, M.

'^j^^a. Cedar and pine as farm trees for Oklahoma.

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1949b. Observations on Japanese red pine and black pine

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1955. Storage of afterripened seed of eastern redcedar.

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AND AsHDOWNj D.

1951. The pine tip moth. Okla. Agr. Expt. Sta. Bui.

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AND CRESS, M.

1942a. Producing seedlings of eastern redcedar {Juniperus

virginiana L.). Okla. Agr. Expt. Sta. Bui. B-256, 21

pp., illus.

AND CRESS, M.

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ENGSTROM, ALBERT, AND JOHNSON, ERNEST W.

1959. Effects of planting dates and storage on survival of

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1947. Pine tip moth and its control in Oklahoma. Jour.

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ALBERTSON, F. W.

1940. Studies of native redcedars in west central Kansas.

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ALLAWAY, W. H.

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ALLEN, G. S.

1957. Storage behavior of conifer seeds in sealed containers held at 0° F., 32° F., and room temperature.

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ALLEN, R. M.

1952. Ferbam controls nursery weeds. U.S. Forest Serv.

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ALLISON, F. E., AND ANDERSON, M. S.

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1934. Root development in seedlings in relation to soil

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ANDERSON, D. A., AND KINEER, G. U. , . , •

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1935. Storage of some coniferous seeds. Boyce Ihompson Inst. Contrib. 7: 379-404, illus.

1951. Germination of seeds of Juniperus virgimana.

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1954 Effect of subfreezing temperatures on viability of

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748-005 0-65—7
82 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

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1952. Pathology in forest practice. Ed. 2, 601 pp., illus.

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1939. Report of planting experiments to determine the

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BRISCOE, CHARLES G., AND STRICHLAND, FREDDIE R.

1956. Vapam shows promise as a forest nursery herbicide

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BROWN, GEORGE K.

1937. Results in survival following cold storage of planting stock. U.S. Forest Serv. Planting Quart. 6: 21-24.

BULL, W. IRA.

1954. Machine for applying sand or sawdust to seedbeds.

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BÜSSE, J.

1930. Forstlexikon. Vol. 2, 423 pp. Berlin: Paul Parey.

CALLAHAM, R. J., AND METCALF, WOODBRIDGE.

1959. Altitudinal races of Pinus ponderosa confirmed

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CAROSELLI, N. E.

1957. Juniper blight and progress on its control. U S

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CAVENESS, F. E.

1957. Root lesion nematode recovered from eastern redcedar at Halsey, Nebraska. U.S. Agr. Res. Serv. Plant

Dis. Rptr. 41: 1058.

CHADWIGK, L. C.

1938. Green manure crops and fertilization for nursery

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CHAPMAN, A. G.

1936. Scarification of black locust seed to increase and

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1948. Bibliography of the literature on the minor elements

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CLIFFORD, E. D.

1934. Quack grass and white grubs. U.S. Forest Serv.

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1952. Use of 2,4-D to control weeds in conifer nurseries.

U.S. Forest Serv. Tree Planters' Notes 12: 6.

1955. The use of sawdust as a mulch on red, white, and

jack pine seedbeds. U.S. Forest Serv. Tree Planters'

Notes 21: 24^25.

1956a. Seedbed root pruner. U.S. Forest Serv. Tree

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1956b. Use of a potato digger for lifting nursery stock.

U.S. Forest Serv. Tree Planters' Notes 24: 9-10.

1959. A rapid method of fumigating nursery soils with

methyl bromide. U.S. Forest Serv. Tree Planters' Notes

37: 9-10, illus.

COCKERILL, J.

1957. Experiments in the control of damping-oflf of the

nursery, Orono, Ontario. Forest. Chron. 33: 201-204.

COCKERILL, P. W., HUNTER, B., AND PINGREY, H. B.

1939. Type of farming and ranching areas in New

Mexico. N. Mex. Agr. Expt. Sta. Bui. 261, 68 pp., illus.

CoLBRY^ VERA L., SW^OFFORD, THOMAS F., AND MOORE,

ROBERT P.

1961. Tests for germination in the laboratory. U.S. Dept

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COLMAN;, E. A.

1947. Manual of instruction for use of the fiberglass soil

moisture instrument. U.S. Forest Serv. Calif. Forest

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CORSON, G. W.

1935. The Susanville Nursery transplant plow. U.S.

Forest Serv. Planting Quart. 4 (2) : 6.

COSSITT, F. M.

1937. The W. W. Ashe nursery seedling lifter. U.S.

Forest Serv. Planting Quart. 6:11.

CRAIGHEAD, F. C.

1950. Insect enemies of eastern forests. U.S. Dept. Agr.

Misc. Pub. 657, 679 pp., illus.

CRAM, W. H.

1951. Spruce seed viability: dormancy of seed from four

species of spruce. Forest. Chron. 27: 349-357.

1956a. Maturity of Colorado spruce cones. Forest Sei.

2: 26-30.

1956b. Fungicidal control of Rhizoctonia damping-off.

U.S. Forest Serv. Tree Planters' Notes 24: 17-18.

1957. Maturity of white spruce cones and seed. Forest

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- AND BRACK, C. G. E.

1953. Performance of Scotch pine races under prairie

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• AND VAARTAJA, O.

1957. Rate and timing of fungicidal soil treatments.

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CUMMINGS, W. H.

1942. Exposure of roots of shortleaf pine. Jour. Forestry

40: 490-492.

CURTIS, JAMES D., AND LYNCH, DONALD W.

1957. Silvics of ponderosa pine. U.S. Forest Serv. Intermountain Forest and Range Expt. Sta. Misc. Pub. 12,

37 pp., illus. (Ogden, Utah.)
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 83

DALE, J., AND MCCOMB, A. L.

1955. Chlorosis, mycorrhizae, and the growth of pines on

a high-Hme soil Forest Sei. 1: 148-157.

DAVIS, WILLIAM G.

1940. Abhor alkaline sands. U.S. Forest Serv. Planting

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AND LATHAM, DENNIS H.

1939. Cedar blight on wilding and forest tree nursery

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WRIGHT, ERNEST, AND HARTLEY, CARL.

1942. Diseases of forest-tree nursery stock. U.S. Fed.

Security Agency, Civ. Conserv. Corps Forestry Pub. 9,

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1934. Stratification vs. scarification for cedar seed. U.S.

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DEFFENBACHER, FORREST W., AND WRIGHT, ERNEST.

1954. Refrigerated storage of conifer seedlings in the

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1924. Injurious shade tree insects of the Canadian prairies.

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1936. Annual planting report. U.S. Forest Serv., Region

1, 72 pp.

1938. Annual planting report. U.S. Forest Serv., Region

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1946. Annual planting and nursery report. U.S. Forest

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DENGLER, ALFRED.

1944. Waldbau. Ed. 3, 596 pp., illus. Berlin: Springer

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1954. Square pots for transplants. U.S. Forest Serv. Tree

Planters' Notes 16: 10-16, illus.

DuFFiN, ROBERT B.

1955. Irrigation water from wells. Okla. Agr. Col. Ext.

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ENGSTROM, ALBERT.

1950. Mulching seedbeds with cellophane. Jour. Forestry 48: 283.

1955. Polyethylene film for seedbed mulch. U.S. Forest

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ENGSTROM, HAROLD E.

1941. Utilizing the warehouse for storage of conifers.

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AND STOECKELER, J. H.

1941. Nursery practice for trees and shrubs suitable for

planting on the Prairie Plains. U.S. Dept. Agr. Misc.

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FARNSWORTH, G. E., LEA, R. V., AND ENGELKEN, JOHN.

1956. Mulching coniferous transplant beds with sawdust.

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FAS SETT, NORMAN G.

1944. Juniperus virginiana, ]. horizontalis, and /.

scopulorum. Torrey Club Bui. 71: 410-418.

FEUSTEL, IRVIN G.

1938. The nature and use of organic amendments. U.S.

Dept. Agr. Yearbook 1938: 462-468.

FISCHBACH, P, E., SCHLEUSENER, P. E., AND DREESZEN, V. H.

1957. Nebraska minimum standards for artificially gravel

packed irrigation wells. Nebr. Agr. Expt. Sta. Ext. Cir.

57-702, 18 pp., illus.

FLEMION, F.

1941. Further studies of the rapid determination of the

germinative capacity of seeds. Boyce Thompson Inst.

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FOGEL, MARTIN.

1957. Selection of pumping equipment for irrigation. S.

Dak. Agr. Ext. Serv. Cir. 503 (Rev.), 16 pp., illus.

FOOD AND AGRICULTURAL ORGANIZATION.

1954. Soil-potta press. FAO Equip. Note A-3, 1 p.

FOSTER, A. A.

1959. Nursery diseases of southern pines. U.S. Forest

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FosTkR, C. H.

1932. Technical forest practices in New York—improvements in planting stock production. Jour. Forestry

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FOWELLS, H, A.

1943. The effect of certain growth substances on rootpruned ponderosa pine seedlings. Jour. Forestry 41 :

685-686.

1953. The effect of seed and stock size on survival and

early growth of ponderosa and Jeffrey pine. Jour.

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AND SCHUBERT, G. H.

1953. Planting stock storage in the California pine region.

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Tech. Paper 3, 12 pp.

Fox, J. W.

1937. Annual nursery report. U.S. Forest Serv., Savenac

Nursery, Haugan, Mont., 55 pp., illus.

1939. Annual nursery report. U.S. Forest Serv., Savenac

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1940. Improved transplanting equipment. U.S. Forest

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FREAR, D. E. H.

1959. Pesticide handbook. Ed. 11, 249 pp. State College, Pa. : Col. Sei. Pub.

FUTRELL, L. M.

1959. Seedbed smoother. U.S. Forest Serv. Tree Planters'

Notes 38: 1, illus.

GAMBRELL, F. L., AND HEIT, C. H.

1952. Soil chemicals in evergreen seedbeds. Amer. Nurseryman 95 (10): 9-10, illus.

GARLOUGH, F. E., AND SPENCER, DONALD A.

1944. Control of destructive mice. U.S. Fish and Wildlife Serv. Conserv. Bui. 36, 37 pp., illus.

GEORGE, ERNEST J. r - M u

1939, Tree planting on the drier sections of the Northern Great Plains. Jour. Forestry 37: 695-698.

1953. Tree and shrub species for the Northern Great

Plains. U.S. Dept. Agr. Cir. 924, 46 pp., illus.

1957. Shelterbelts for the Northern Great Plams. U.S.

Dept. Agr. Farmer's Bui. 2109, 16 pp., iHus.

GOODFELLOW, VANCE V., AND CoLBERG, W. J.

1958. Insect pests of evergreens. N. Dak. Agr. C.ol.,

Cir. A-297, 5 pp., illus.

Goss, R. W. . ...11 _,,,

1960 Mycorrhizae of ponderosa pme m Nebraska grassland soils. Nebr. Agr. Expt. Sta. Res. Bui. 192, 47 pp.,

illus.

GRAHAM, S. A. .-^

1939. Principles of forest entomology. Ed. ¿, ^lU pp.,

illus. New York.

GRAHAM, SAMUEL A., AND BAUMHOFER, LYNN G.

1927 The pine tip moth in the Nebraska National Forest.

Jour. Agr. Res. 35: 323-333.

GREB, B. W., AND BLACK, Al. i- ^ ^^^c

1961. Effect of windbreak plantmgs on adjacent crops.

Jour. Soil and Water Conserv. 16: 223-227.

HAAS, H.G., AND EVANS, C.E. . * pioir.. cniU

1957. Nitrogen and carbon changes m Great Plams sous

as influenced by cropping and soil treatments. U.b.

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T9T4' Result of an experiment on the effect of drying in

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84 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

HALL, MARION TRUFANT.

1952. Variation and hybridization in Juniperus. Ann.

Mo. Bot. Garden 39: 1-64, illus.

HALL, RALPH G.

1936. Control of the Nantucket pine tip moth in the Central States. U.S. Bur. Ent. and Plant Quart., 5 pp.

HANKS, SIDNEY H.

1962. A seven-row seedhng transplanter for nursery use.

U.S. Forest Serv. Tree Planters' Notes 53: 20-22.

HANSEN, N. E.

1930. Evergreens in South Dakota. S. Dak. Agr. Expt.

Sta. Bui. 254, 33 pp., illus.

HARTLEY, G.

1915. Injury by disinfectants to seeds and roots in sandy

soils. U.S. Dept. Agr. Bui. 169, 35 pp., illus.

1917. The control of damping off of coniferous seedlings.

U.S. Dept. Agr. Bui. 453, 32 pp., illus.

1918. Stem lesions caused by excessive heat. "^^ )ur. Agr.

Res. 14: 595-604.

1921. Damping-off in forest nurseries. U.S. Dept. Agr.

Bui. 934, 99 pp., illus.

1935a. Prevention of diseases of conifers in nurseries and

plantations. U.S. Bur. Plant Indus., 27 pp.

1935b. Undesirable practices from the standpoint of effect

on damping-off liability. U.S. Forest Serv. Planting

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HARVEY, R. B.

1930. Length of exposure to low temperature as a factor

in the hardening process in tree seedlings. Jour. Forestry 28: 50-53, illus.

HASTINGS, W. G.

1923. Revolutionizing nursery practice. Tour. Forestry

21: 180-182.

HEIT, G. E.

1955. The excised embryo method for testing germination

quality of dormant seed. N.Y. State Agr. Expt. Sta.

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HERMAN, F. R.

1958. Silvical characteristics of Rocky Mountain juniper.

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HiGGiNs, JAY,

1928. Effect of density on seedling development. Jour.

Forestry 26: 909-912.

HiLL^ JOSEPH A.

1955. Methyl bromide gas controls weeds, nematodes, and

root rots in seedbeds. U.S. Forest Serv. Tree Planters'

Notes 21: 11-14.

HODGES, GHARLES S., JR.

1962. Diseases in southeastern forest nurseries and their

control. U.S. Forest Serv. Southeast. Forest Expt. Sta

Paper 142, 16 pp., illus. (Asheville, N.G.)

HoLMESj G. D., AND BuSZEVS^IGZ, G.

1958. The storage of seed of temperate forest tree species.

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AND IvENS, G. W.

1952. Ghemical control of weeds in forest nursery seedbeds. Great Britain Forest. Comm., Forest Rec. 13, 31

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HOLMES, R. E., AND BROWN, J. G,

^^^L^ ^^^"^ ^^^ soil fertility. U.S. Dept. Agr. Yearbook

1957: 111-115.

HOWELL, J. R.

1932 The development of seedlings of ponderosa pine in

relation to soil types. Jour. Forestry 30: 944-947.

HUTCHISON, S. B., AND KEMP, P. D.

1952. Forest resources of Montana. U.S. Forest Serv

Forest Resource Rpt. 5, 76 pp., illus.

IMPERIAL INSTITUTE OF LONDON.

1936. Some minor, mineral fertilizer materials. Imp

Inst. London Bui. 34 (2): 212-219.

JANOUCH, KARL L.

1927. Effect of spacing and root pruning on the development of transplants. Jour. Forestry 25: 62-67.

JOHNSENJ THOMAS N., JR.

1959. Longevity of stored juniper seeds. Ecol. 40:

487-488.

JOHNSON, E. W.

1955. A simple device for making paper pots. U.S.

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AND VANDERSLICE, G. G.

1956. An improved device for making paper pots. U.S.

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JOHNSON, PHILLIP G.

1958. Spruce spider mite infestations in northern Rocky

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14 pp., illus. (Ogden, Utah.)

JONES, D. L., GAINES, FRANK, AND KARPER, R. E.

1932. Trees and shrubs in northwest Texas. Tex. Agr.

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1925. Forest nursery working practice at Savenac Nursery. Jour. Forestry 23: 635-644.

1934. Spring sowing versus fall sowing white spruce—

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JORDAN, HOWARD V., AND REISENAUER, H. M.

1957. Sulphur and soil fertility. U.S. Dept. Agr. Yearbook 1957: 107-110, illus.

KALELA, AARNO.

1937. Zur Synthese der experimentellen Untersuchungen

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KEEN, F. P.

1952. Insect enemies of western forests. U.S. Dept. Agr.

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KELLEY, ARTHUR PIERSON.

1930. II. Mycorhiza studies. The duration of certain

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1922. Ergebnis der Versuchsanpflanzung von Kiefern verschiedener Herkunft in der ObeiSörsterei Chorin.

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KNIGHT, H.

1956. Growning green manure crops at a forest nursery.

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1958. A test to determine acceptability of sawdust as a

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KOPITKE, J. C.

1941. The effect of potash salts upon the hardening of

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KoRSTiAN, G. F., HARTLEY, CARL, WATTS, L. F., AND HAHN,

GLENN G.

1921. A chlorosis of conifers corrected by spraying with

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LANGLET, OLOF.

1936. Study of the physiological variability of pine and its

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LANQUIST, KARL B.

1945. Leaf litter in forest nurseries. Jour. Forestry 43:

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1946. Tests of forest tree seed in California. Jour. Forestry 44: 1063-1066.

1951. Allyl alcohol application through the overhead

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CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 85

LANQUIST, KARL B. MoNY, CHARLES G.

1954a. Seedling harvester. U.S. Forest Serv. Tree Planters' Notes 16: 5-6, illus.

1954b. Seed cleaning and dewinging machine. U.S. Forest Serv. Tree Planters' Notes 18: 8-9, illus.

LEVITT, J.

1956. The hardiness of plants. 278 pp., illus. New York.

LITTLE, ELBERT L., Jr.

1950. Southwestern trees, a guide to the native species of

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1953. Check list of native and naturalized trees of the

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LIVINGSTON, R. B.

1949. An ecological study of the Black Forest, Colorado.

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MGARDLE, RICHARD E.

1932. The relation of mycorrhizae to conifer seedlings.

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1943. Mycorrhizae and phosphorus nutrition of pine seedlings in a prairie soil nursery. Iowa Agr. Expt. Sta.

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MGDANIEL, VERN E.

1954. Roto-tiller cultivator. U.S. Forest Serv. Tree Planters'Notes 18: 13-15, illus.

MGDERMOTT, R. E., AND FLETCHER, P. W.

1955. Influence of light and nutrition on color and growth

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MAKI, T. E.

1940. Seed maturity in ponderosa pine. Jour. Forestry

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1952. Use of allyl alcohol for weed control in forest nurseries. Jour. Forestry 50: 470-471.

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1958. Bird control in forest nurseries. U.S. Forest Serv.

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MATKIN, O. A., AND CHANDLER, PHILLIP, A.

1957. U.C. type soil mixes for container-grown plants.

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MAYER-KRAPOLL, HERMANN.

1956. The use of commercial fertilizers—particularly nitrogen in forestry. Translated and published by Nitrogen Div. Allied Chemical and Dye Corp., 111 pp., illus.

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MEINEGKE, E. P.

1929. Experiments with repeating pine rusts. Phytopath.

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MEINES, M. K.

1939. Broadcast versus drill sowing of conifers. U.S. Forest Serv. Planting Quart. 8:3.

MELIN, E.

1927. Studies of the development of coniferous plants in

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MIROV, N. T.

1936. A note on germination methods for coniferous

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MONSON, O. W.

1952. Sprinkler irrigation in Montana. Mont. State Col.

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• GRIDDLE, WAYNE D., AND DAVIS, STERLING.

1953. Estinrated water requirement of crops in irrigated

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MoNY, CHARLES C.

1935. Leveling a new nursery. U.S. Forest Serv. Planting

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1941. Top and root pruning cleaver. U.S. Forest Serv

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1954. Vallonia rotary tooth cultivator. U.S. Forest Serv

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1958. Seed pelleting process for bird and disease control

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1961. Observations on the use of methyl bromide. U.S.

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MOORE, O, W.

1960. Ammonium nitrate fertilizer can explode. U.C.

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MULLINS, R. E.

1956. Moisture retaining materials for nursery stock packaging. Ontario Dept. Lands and Forest Res. Rpt. 34,

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MUNGER, T. T.

1941. Regional strains of ponderosa pine show pronounced

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MuNNECKE, DONALD E.

1957. Chemical treatment of nursery soils. In The U.C.

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NIENSTAEDT, HANS.

1957. Silvical characteristics of white spruce. U.S. Forest

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NiKiFOROFF, CONSTANTIN C.

1938. Soil organic matter and soil humus. U.S. Dept.

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NoRUM, E. B., KRANTZ, B. A., AND HAAS, H. J.

1957. The Northern Great Plains. U.S. Dept. Agr. Yearbook 1957: 494-504.

OLIVER, D. A.

1937. Improvements on Yale transplant board. U.S.

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1930. Growing trees for forest planting in Montana and

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ON^ DANNY.

1952. 2,3,5-triphenyl tetrazolium chloride as a viability

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1932. Flora of South Dakota. Univ. S. Dak., Ibl pp.,

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1921. After-ripening and germination of juniperus seed.

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PARKER, J. R., AND COWAN, F. T.

1953. Grasshopper control. U.S. Dept. Agr. FA-14-y,

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PEARSON, G. A. „

1914. Forest planting in Arizona and New Mexico. Î50C.

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PETERSON,L.O. T., AND WORDEN, H.A. , „ ^ .

1959. Summary report. Canada Dept. Agr., Res. Branch,

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PIETERS, A. J., AND MCKEE, ROLAND.

1938 The use of cover and green-manure crops, u.ö.

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^^933.^^Temperature only one factor in storing nursery

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PLANK, DONALD K. . ... , . , .,

1939. Root response of slash pine seedlings to indolebutyric acid. Jour- Forestry 37: 497-498, illus.

POTTER, L. D. . , ., y^^t TT-^

1952. North Dakota's heritage of pine. N. Dak. iiist.

19: 157-166, illus.
86 AGRICULTURE HANDBOOK 2 7 9, U.S. DEFT. OF AGRICULTURE

POTTS, S. F.

1952. Control of forest and shadetree insects with concentrated sprays applied by mist blowers. In Important

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1952. Spraying and dusting to control insects and diseases. In Important tree pests of the Northeast, pp.

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PRENTICE, R. M., AND HILDAHL, V.

1959. Provinces of Manitoba and Saskatchewan, forest

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PRITCHARD, A. EARL, AND BAKER, EDWARD W.

1955. A revision of the spider mite family Tetranychidae.

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1955. Grading of transplants may improve initial survival of ponderosa pine in Plains windbreaks. U.S. Dept.

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1958. The Great Plains Shelterbelt in 1954. Great Plains

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RICHARDS, L. A., et al.

1954. Diagnosis and improvement of saline and alkaline

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ROBBINS, P. W.

1932. Use of paper mulch in the nursery. Jour. Forestry 30: 415-418.

1935. An iron seedbed stake for forest nurseries. Jour.

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1942. A grading and counting machine for forest nursery

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1947. Report on chemical weed control for conifer

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RoESER, JACOB, JR.

1932. Transpiration capacity of coniferous seedlings and

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1940. The water requirements of Rocky Mountain conifers. Jour. Forestry 38: 24-26.

1941. Some aspects of flower and cone production in

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ROGERS, T. HAYDEN, AND GIDDENS, JOEL E.

1957. Green manure and cover crops. U.S. Dept. Agr.

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ROSENDAHL, R. O.

1942. The effect of mycorrhizal and non-mycorrhizal

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AND WILDE, S. A.

1942. Occurrence of ectotropic mycorrhizal fungi in soil

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Ross, NORMAN M.

1937. Dominion forest nursery station's results of experiments 1932-1936, inclusive. Canada Dept. Agr. Pub.,

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RUDOLF, PAUL O.

1952. Low temperature seed storage for western conifers.

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1956. Guide for selecting superior forest trees and stands

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RussEL, DARRELL A.

1957. Boron and soil fertility. U.S. Dept. Agr. Yearbook

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SAF SEED CERTIFICATION SUBCOMMITTEE.

1963. The seed we use: Part ii. How to assure reliable

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1938. Farm manure. U.S. Dept. Agr. Yearbook 1938:

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SCHNEIDER, H. W.

1937. Pruning roots hastens hardening-off of jack pine.

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SCHRADER, W. H.

1938. The evolution of the transplant board at the Monument nursery. U.S. Forest Serv. Planting Quart.

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SCHUBERT, G. H.

1954. Viability of various coniferous seeds after cold

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SHARKEY, T. M.

1956. Sheltering the seedbed. U.S. Forest Serv. Tree

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SHAV^, DALE L.

1963. A homemade tree potting system. U.S. Forest

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SHEMAHANOVA, N. M.

1957. Role of mycorrhiza-forming fungi in the nutrition

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1936. Lethal high temperatures for conifers and the

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1939. Influence of moisture supply on drought resistance

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1917. EflFect of depth of covering seed upon the germination and quality of stock. Jour. Forestry 15: 619-623.

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1942. Diplodia epidemic in conifer seedbeds. Phytopath.

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1943. Diplodia blight in coniferous seedbeds. Phytopath.

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SOWASH, R. O.

1936. Cold storage of seedlings and its effect upon survival in the field. U.S. Forest Serv. Planting Quart. 5

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1954. Agitator type mechanical tree lifter. U.S. Forest

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1961. White grubs in forest tree nurseries and plantations.

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1961. Chemical weed control in the nursery. Minn.

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1940. The hammermill as an important nursery implement. Jour. Forestry 38: 356-361, illus.

1952. Experiences in using allyl alcohol for weed control.

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STEWART, L, AND LEONARD, C. D.

1952. Chelates as sources of iron for plants growing in

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STOECKELER, J. H.

1939. Nursery soil moisture content. U.S. Forest Serv.

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1946. Alkali tolerance of drought-hardy trees and shrubs

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CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 87

STOECKELER, J. H.

1951a. Proper watering in the nursery produces droughthardy jack pine. U.S. Forest Serv. Lake States Forest

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1951b. Hydrocarbon content and storage period affect

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1951c. Killing weed seeds. Amer. Nurseryman 93 (8) :

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1952a. A northeastward extension of the range of Douglas-fir. Jour. Forestry 50: 393.

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1940. The use of tensiometers in regulating watering in

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1960. Fertilizers in forestry. Adv. in Agron. 12: 127-

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1937. The Denbigh disk scarifier, a new method of seed

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1957. Forest nursery practice in the Lake States. U.S.

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1951. Allyl alcohol for weed control in forest nurseries.

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1949. Winter injury and recovery of conifers in the Upper

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1956. Winter coloration and growth of jack pine in the

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1955. Poor survival and the physiological condition of

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1940. Nursery bed shaper. Jour. Forestry 38: 515-517.

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1952. Damping-off in the forest tree nursery and its control. Mich. Agr. Expt. Sta. Quart. Bui. 34: 285-296,

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1915. The cypress and juniper trees of the Rocky Mountain region. U.S. Dept. Agr. Bui. 207, 36 pp., illus.

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1941. Germination behavior of tree seeds as observed in

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1954. Operation manual for TVA forest nurseries.

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1955. Effect of soil fumigation on nitrification. Down

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1953. Provinces of Manitoba and Saskatchewan forest

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1955. Cost of distribution of irrigation water by different

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1942. Seeding and planting in the practice of forestry.

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1946. Soil reaction influence on availability of plant nutrients. Soil Sei. Soc. Amer. Proc. 11: 305-306, illus.

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1946. Nursery weeding costs reduced by mechanical cultivation. Jour. Forestry 44: 379-380, illus.

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1936. Seed and nursery practice. Shelterbelt Proj. Pub.,

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1954. Annual report, forest research in California. 70 pp.,

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1932. Fertilizers and crop production. 493 pp., illus.

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1925 Forestation research in Montana and north lûano.

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1954. Dominion forest nursery stations progress report

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1936 Forests of South Dakota—their economic importance and possibilities, U.S. Forest Serv., Lake States

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88 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

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1939. Evidences of racial influences in a 25-year-old test

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1941. Prairie soil as a medium for tree growth. Ecology

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1956. Forest fertilization. N.Y. State Univ. Col. Forestry

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1955. Effect of wind variation on water distribution from

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1956. Effect of biocides on the development of ectotrophic

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1948. Tests on the adaptability of trees and shrubs to

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1952. Green manure crop causes seedling mortality. U.S.

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1954. An analysis of nursery stock production costs in relation to the use of mineral spirits. U.S. Forest Serv.

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1936. Insect control in shelterbelts on the Great Plains.

U.S. Bur. Ent. and Plant Quart., 51 pp.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS

APPENDIX

89

COMMON AND SCIENTIFIC NAMES OF TREES AND SHRUBS MENTIONED

Conifers

Arborvitae, oriental (Chinese) . Thuja orientalis L.

Cypress, Arizona Cupressus arizonica Greene.

Douglas-fir Pseudotsuga menziesii

(Mirb.) Franco.

Fir balsam Abies balsamea (L.) Mill.

Fir' Siberian Abies sibirica Ledeb.

Juniper, alligator Juniperus deppeana Steud.

Juniper, Ashe /• ashei Buchholz.

Juniper, common /• communis L.

Juniper, oldfield common . . . /. communis var. depressa

Pursh.

Juniper, one-seed /. monosperma (Engelm.)

Sarg.

Juniper, Pinchot /. pinchotii Sudw.

Juniper, Rocky Mountain . . /. scopulorum Sarg.

Juniper, Utah /. osteosperma (Torr.) Little.

Larch, European Larix decidua Mill.

Larch, Siberian L. sibirica Ledeb.

Pine, Austrian Pinus nigra Arnold.

Pine, Digger P. sabiniana Dougl.

Pine, It^ian stone P. pinea L.

Pine, jack P. banksiana Lamb.

Pine, Japanese black .... P. thunbergi Pari.

Pine, Japanese red P. densiflora Sieb & Zuce.

Pine, Jeffrey P. jeffreyi grev. and Balf.

SAFETY RULES AND PRECAUTIONS

FOR HANDLING, MIXING,

AND APPLYING CHEMICALS

Most insecticides and fungicides and some other

sprays and baits contain poisons injurious, if not

deadly, to humans and livestock. Many act through

the skin or lungs as well as through the digestive tract.

In addition, some are flammable or explosive, or involve other hazards. Wakeley (1954) lists some general rules which, if properly enforced, should minimize

accidents occurring when poisons and other hazardous

materials are handled. They are as follows:

1. Plainly mark both temporary and permanent

containers to show nature of contents (poisonous, flammable, etc.) and date of purchase (some chemicals

change or deteriorate with age). Keep dangerous

materials tightly closed (unless their nature requires

venting) ; out of reach of children, irresponsible persons, livestock, and pets; and in an adequately ventilated storeroom, preferably locked.

2. When mixing or applying poisonous materials,

be extremely careful to keep them out of the mouth,

eyes, nose, and lungs, and away from tender parts of

the body. Ordinarily, wear leather or paraffined-cloth

gloves (rubber or plastic gloves must be used with

certain chemicals), and always wear goggles, a respirator, or a combination of the two. If the manufacturer specifies, mix substance only in open shed or

outdoors.

Pine, limber P. flexilis James.

Pine, loblolly P. taeda L.

Pine, lodgepole P. contorta Dougl.

Pine, ponderosa P. ponderosa Laws.

Pine, red P. resinosa Ait.

Pine, Scotch P. sylvestris L.

Pine, shortleaf P. echinata Mill.

Pine, Swiss stone P. cembra L.

Pine, Virginia P. virginiana Mill.

Pine, western white P. monticola Dougl.

Pinyon P. edulis Engelm.

Redcedar, eastern Juniperus virginiana L.

Spruce, blue Picea pungens Engelm.

Spruce, Engelmann P. engelmannii Parry.

Spruce, Siberian P. obovata Ledeb.

Spruce, Sitka P. sitchensis (Bong.) Garr.

Spruce, white (includes Black

Hills) P. glauca (Moench) Voss.

Tamarack Larix laricina (Du Roi) K,

Koch.

Broadleaves

Cottonwood, eastern .... Populus deltoides Bartr.

Elm, Chinese Ulmus parvifolia Jacq.

Elm, Siberian U. pumila L.

Oak, bur Quercus macrocarpa Michx.

Peashrub, Siberian Caragana arborescens Lam.

Rose, Japanese Rosa multiflora Thunb.

3. Prohibit smoking during the mixing or application of flammable or explosive substances.

4. Bum or bury empty packages and bags that

have contained poisons. Bury unused or discarded

materials. When mixing vessels, sprayers, etc., are

washed after use of the more poisonous substances,

empty washwater into a hole in the ground, and fill in

the hole. Do not bum empty arsenical containers

except in open air. (Addition by authors: Avoid

breathing smoke or fumes from burning empty chemical containers.)

5. Always wash hands and face thoroughly after

mixing or applying poisonous substances. After long

exposure, bathe and change clothes. Wash the clothes

after each day's spraying.

6. Be sure that no poisonous spray matenal can

get into domestic or livestock water supplies.

7 If sulfuric acid must be diluted (as for acidifying soil to control damping-ofl"), always pour the acid,

which is the heavier liquid, into the water. Water

poured into sulfuric acid spatters badly, with serious

danger, especially to the eyes.

Only the most responsible and trustworthy personnel should be allowed to handle chemicals that are

explosive, flammable, or toxic to humans. It is extremely important that the directions on the labels on

insecticides, fungicides, or weed killers be carefully

read and followed. Containers for chemica s that

have been emptied should be stored in a safe place or

destroyed. Surplus mixtures should be buried and

covered with soil. They should not be poured into
90 AGRICULTURE HANDBOOK 2 79, U.S. DEPT. OF AGRICULTURE

Streams or ponds where they may endanger human life,

fish, or livestock.

Workers handling concentrated acid should be

equipped with goggles, rubber gloves, and acidproof

aprons. Once the acid is diluted to a 2-percent solution, it is not particularly hazardous to handle.

Workers should not breathe the fumes of chemicals,

especially methyl bromide, allyl alcohol, and parathion (Frear 1959). In the manual application of

methyl bromide, special injectors, as supplied or

recommended by the manufacturer of the chemical,

should be used. Masks or respirators should be worn

when handling allyl alcohol, methyl bromide, Ferbam,

and parathion.

Allyl alcohol, methyl bromide, chlordane, Ferbam,

nicotine, and parathion should not be brought into

contact with the skin. This precaution should also

be observed when handling seedlings treated with such

chemicals as Endrin and nicotine. These chemicals

are used to repel rabbits after fieldplanting.

Some chemicals, such as carbon disulfide, are explosive. Others, such as chlorates and mineral spirits,

are quite flammable. Ammonium nitrate (Moore

1960) and allyl alcohol are both explosive and flammable. Therefore, they must be stored in well-ventilated buildings well separated from warehouses and

other buildings.

Certain insecticides are harmful to bees, which help

pollinate many plants. If spraying with DDT is necessary, it should be done when the flowers are in the bud

rather than the bloom stage. However, if the flowers

are in bloom, toxaphene can be sprayed in the early

morning or late evening.

Use of oil sprays in the summer is not recommended

because the oil may injure the foliage or new growth of

small nursery trees. In the dormant season, sprays

should be thoroughly mixed or emulsified before application. Oil emulsions of more than 4 percent strength

may damage trees. If oils or oil emulsions are used,

tanks must, in most cases, be reasonably free of any

hme sulfur residues, since these may break down the

emulsion.

Many insecticides and fungicides tend to stain wood,

painted surfaces, and stone. The stain damage caused

by direct application or drift can be lessened by thoroughly wetting the object before and after an application. ^

Sprayers used for weed or brush killers, such as 2,4-D

or 2,4,5-T, should not be used for spraying insecticides

or fungicides in the nursery because minute residues

of these chemicals may damage or kill the trees. If it

IS necessary to use these sprayers, they should be

scrubbed out thoroughly with soap and water and

rinsed repeatedly.

SPRAY FORMULAS FOR

INSECTICIDES AND FUNGICIDES

A number of well-tested formulas have been deT.^^^'^J'"'' P^^eparing insecticides and fungicides

Use of these formulas will help

nurserymen protect nursery beds as well as larger trees

in windbreaks near the nursery.

TABLE 20.—Formulas for insecticides and fungicides,

after Potts and Waterman {1952)

Formu- Sticker or

la No. Ingredients Water spreading

agent

INSECTICIDES

Gallons

1 Lead arsenate 2 to 5 (av. 100 1 pt. of fish

4) lb. oil.

2 Derris or cube powder 100 }i gal. fish

4% rotenone) 2-8 lb. oil.

3 Nicotine sulfate (40% 100 '3 lb. solid

nicotine) 1 pint. soap or 6

lb. liquid

4 Pyrethrum powder (0.8

to 1% pyrethrins) 1 lb.

100

soap.

Do.

5 Emulsifiable pyrethrum

extract (1% pyrethrins) 1 pint.

100 None.

6 Derris or cube powder 100 3 lb. soHd

(4% rotenone) 1.5 lb. soap or 6

lb. liquid

7 Oil emulsion (75% oil) 4

gal.

Miscible oil (90% oil) 5

96

soap.

None.

8 95 Do.

gal.

9 Miscible white oils 1 gal... 100 Do.

10 Lime sulfur (10 gal.

liquid or 40 lb. dry).

90 Do.

11 Parathion 1 lb 100

100

Do

11a Tetraethyl pyrophos- Do.

phate (40% emulsifiable) y2 pt.

12 Aramite 15 W. Neotran,

or Dimite, 2 lb.

100 Do.

13 DDT (emulsifiable, 25%

DDT) 1 qt.

100 Do.

13a DDT (50% DDT wettable powder) 1 lb.

FUNGICIDES

100 Do.

14 Lime sulfur (2.5 gal.

liquid or 6-8 lb. dry).

100 None.

15 Bordeaux-copper sulfate 8 100 Calcium

Ib., hydrated lime 10 caseinate

lb. 2 1b.

16 Bordeaux mixture powder

16 1b.

100 Do.

17 Wettable sulfurs 0) According

to directions on

container.

18 Sulfur dust 2 0

100

None.

19 Puratized agricultural Do.

spray 1 to 1.5 pts.

20 Ferbam 1.5-2 lb 100

100

Do.

21 Ferbam }^ lb., wettable Do.

sulfur 3 lb.

22 Elgetol 1 gal 100 Do.

(tables 20 and 21).

^ According to directions on container.

2 For control of chewing insects, 2 pounds of lead arsenate or

1 pound of 50 percent DDT powder can be added per 10 pounds

of sulfur.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS

TABLE 21—Concentrated-spray formulations for use in mist blowers, aircraft, and hand atomizers,

after Potts {¡952)

91

Formula No.

4

5

6

7

8

9

10

11

12

13

14

15

16

17

Ingredients

DDT

Kerosene

DDT, technical

Xylene

Kerosene

DDT, technical

Xylene

Triton X-100

Water

DDT, 50% wettable powder

Water

Benzene hexachloride, emulsifiable 20% gamma

isomer.

Water

Ghlordane, 50% emulsifiable

Kerosene or water

Chlordane, 50% wettable powder

Water

Nicotine sulfate

Water

Rotenone, 5% emulsifiable extract

Water

Rotenone, 5% powder

Water

Mineral oil (50 to 90 sec. Saybolt)

Pyrethrum extract, 1 % emulsifiable

Water or kerosene

Lead arsenate

Water

Mineral oil (50 to 90 sec. Saybolt)

Refined white mineral oil (45 to 75 sec. Saybolt). ,

Refined white miscible mineral oil (50 to 100 sec.

Saybolt).

Water

DN-111

Water

Aramite 15W

Water

Soybean oil or linseed oil

Liquid lime sulfur

Quantity to make

Igal.

%lb.

Igal.

Klb.

1% pt

ó%pt

Klb.

l^pt

% oz.

6^2 pt

1 lb..

Igal.

4 oz.

Ipt..

7pt..

1 lb..

Igal.

8 oz. .

ly, pt

ipt..

7pt..

1 lb..

7/2 pt

3 oz.

Ipt..

7pt..

2 1b..

71/5 pt

Hpt.

1 gal.

Iqt..

3 qt..

8 oz.

Igal.

1 lb..

m pt

Vs pt.

Igal.

100 gal.

40 1b...

99 gal..

50 1b...

15% gal

81% gal

50 1b...

152/á gal

fggal..

82 gal..

100 gal.

97 gal..

3K8gal.

97 gal..

12^2 gal

87^2 gal

1001b..

97 gal.,

ó^gal.

933/^ gal

12/2 gal

87>^ gal

100 lb. , 94 gal..

2/2 gal.

12/2 gal

87>^ gal

200 1b..

90 gal..

5 gal...

100 gal.

26 gal..

74 gal..

501b...

98Hgal,

100 1b..

95 gal..

2/2 gal.

100 gal.

Gallons to apply

Per acre

2%

2

6

15

6

6

15

Per 60-ft.

tree

>1

1

1

íy2

1/2

3%

1K2

1/2

3^4

Percent

of

toxicant

.67

6

6

2,5

.6

.6

.125

21

100

25

6

2

100

MOUSiE BAITS

Zinc Phosphide Formula

The zinc phosphide formula (Garlough and Spencer 1944) is as follows:

Steamed rolled oats 98 pounds.

Zinc phosphide 1 pound.

Amber petroleuni jelly 10 ounces.

Mineral oil 10 ounces.

The mineral oil and petroleum jelly are wanned

together until they are fluid, but not hot. Zinc phosphide is added to the mixture and stirred vigorously.

This material is then poured over the oats and mixed

thoroughly. Zinc phosphide baits are generally effective for about 3 weeks after preparation.

Stryehnlne Alkaloid Formula

Because of its bitter taste, strychnine alkaloid sometimes is not as readily accepted by certain mice. The

formula is as follows:

Steamed rolled oats 12 pounds.

Powdered strychnine alkaloid .... 1 ounce.

Baking soda J <^^n^^-

Gloss starch H ounce.

Water J PP^'

Heavy com sirup A Pinr«

Glycerine or petrolatum 1 tablespoonful.

The starch is mixed with one-fourth teacup of cold

water, stirred into three-fourths pint of boiling water,

and cooled until it forms a thin paste. Strychnine is
92 AGRICULTURE HANDBOOK 2 7 9, U.S. DEPT. OF AGRICULTURE

mixed with the baking soda, added to the starch paste,

and stirred until free of lumps. The com sirup and

glycerine or petrolatum are then added. The mixture

is poured over the oats and allowed to dry before

sacking.

SOURCES OF INFORMATION ON NURSERY

PRORLEMS

Nurserymen who have problems with nursery insects

or diseases can obtain advice on identification and control by writing to their State agricultural college or

their State nursery inspector; the latter is invariably a

trained pathologist or entomologist. The inspector

may also send out releases on new quarantine regulations affecting the nursery industry. Another source

of information on nursery disease and insect problems

is the Division of Forest Protection Research, Forest

Service, U.S. Department of Agriculture, Washington,

D.C, 20250.

Advice on control of mammals and birds can be obtained from the Fish and Wildlife Service, U.S. Department of the Interior, Washington, D.C, 20240,

or from the conservation departments of the respective

States.

Nurserymen who plan interstate shipments of stock

should become familiar with Federal and State regulations which may affect their shipments. This information can be obtained from the Plant Quarantine

Division, Agricultural Research Service, U.S. Department of Agriculture, Washington, D.C, 20250.

Problems on nursery soils can be referred to the soils

departments of State colleges and universities.

SOURCES OF INFORMATION

ON NURSERY MACHINERY,

EQUIPMENT, AND CHEMICALS

The nursery industry as much as possible uses equipment and products of standard manufacture. A list of

manufacturers of nursery machinery, equipment, and

chemicals can be obtained from the Forest Service,

U.S. Department of Agriculture, Washington, D.c'

Blueprints of specialized equipment, either assembled from manufacturers' parts or to be built by the

nurseryman, can be obtained from one of the several

regional offices of the U.S. Forest Service.

The North Central Region of the U.S. Forest Service

(consisting of North Dakota, Minnesota, Wisconsin,

Michigan, Iowa, Missouri, Illinois, Indiana, and Ohio)'

has blueprints of certain items of special equipment

(tree lifters, hand trenchers, root pruners, tree balers,

etc.) or of buildings (central warehouses, cold storage

sheds, cone storage sheds, and extractories, etc.).

Nurserymen can obtain these blueprints at cost by

writing to the Regional Forester, U.S. Forest Service

Milwaukee, Wis. '

In the Rocky Mountain Region (consisting of South

Dakota, Nebraska, Kansas, Colorado, and a major

portion of Wyoming) similar blueprints can be obtained by writing to the Regional Forester, U.S. Forest

Service, Denver, Colo.

Requests of nurserymen in Oklahoma and Texas

should be addressed to the Regional Forester, U.S.

Forest Service, Atlanta, Ga.

Nurserymen in Montana can obtain blueprints from

the Regional Forester, U.S. Forest Service, Missoula,

Mont.

REQUIREMENTS AND PROCEDURES FOR

NURSERY STOCK INSPECTION

IN THE PLAINS STATES

Each State has laws requiring inspection of trees

before they can be sold and removed from the nursery

premises. In brief, these laws provide for an annual

inspection of the nursery by the State nursery inspector

or his representative, define the fees to be charged,

and provide for the issuance of a certificate of inspection. The law names certain species on which there is

a quarantine regarding shipment into the State; defines

the power of the nursery inspector to recommend and

enforce destruction of certain pest-infested stock or

to enforce its treatment with appropriate insecticides

or fungicides; provides for tagging State shipments of

nursery stock and wildings; and provides for penalties

for violations of quarantine and other aspects of

nursery regulations.

Individuals in any of the Plains States contemplating growing or selling nursery stock can obtain detailed information on current laws affecting the

business by writing to one of the following agencies:

1. In Colorado : State Department of Agriculture,

3130 Zuni Street, Denver, Colo.

2. In Kansas (for portion of State north of

Smoky Hill and Kansas Rivers) : Nursery Inspector, Department of Entomology, Kansas

State College, Manhattan, Kans.

3. In Kansas (for portion of State south of

Smoky Hill and Kansas Rivers) : Nursery Inspector, Department of Entomology, University of Kansas, Lawrence, Kans.

4. In Montana: State Nursery Inspector, East

Broadway, Missoula, Mont.

5. In Nebraska: State Entomologist and Nursery Inspector, Bureau of Plant Industry, State

Capitol Building, Lincoln, Nebr.

6. In North Dakota: State Nursery Inspector,

North Dakota State University, Fargo, N. Dak.

7. In Oklahoma: Nursery Inspector, Entomology

Division, State Department of Agriculture,

Oklahoma City 5, Okla.

8. In South Dakota: State Nursery Inspector,

State Department of Agriculture, Pierre, S.

Dak.

9. In Texas: State Entomologist, 308 Capitol

Building, Austin, Tex.

10. In Wyoming: State Entomologist, 308 Capitol Building, Cheyenne, Wyo.
CONIFER NURSERY PRACTICE IN THE PRAIRIE-PLAINS 93

Plant quarantine regulations that are in force on a

national basis by the U.S. Department of Agriculture

are available from the Plant Quarantine Division,

Agricultural Research Service, U.S. Department of

Agriculture, Washington, D.C., 20250.

r.lS. DEPARTMENT OF AGRICn^TURE

FOREST TREE SEED POLICY (1939)

The U.S. Department of Agriculture has adopted a

forest tree seed policy regarding seeds of trees and

shrubs to be used in reforestation, shelterbelt, and

erosion control planting. It provides guidance for its

various conservation agencies engaged in such work.

The policy is given below :

Recognizing that trees and shrubs, in common with

other food and fiber plants, vary in branch habit, rate

of growth, strength and stiffness of wood, resistance to

cold, drought, insect attack, and disease, and in other

attributes which influence their usefulness and local

adaptation for forest, shelterbelt, and erosion-control

use, and that such differences are largely of a genetic

nature, it shall be the poUcy of the United States Department of Agriculture insofar as practicable to require for all forest, shelterbelt, and erosion-control

plantings, stocks propagated from segregated strains or

individual clones of proven superiority for the particular locality or objective concerned.

Furthermore, since the above attributes are associated in part with the climate and to some extent with

other factors of environment of the locality of origin, it

shall be the policy of the U.S. Department of Agriculture :

1. To use only seed of known locality of origin

and nursery stock grown from such seed.

2. To require from the vendor adequate evidence

verifying place and year of origin for all lots of seed

or nursery stock purchased, such as bills of lading, receipts for payments to collectors, or other evidence

indicating that the seed or stock offered is of the

source represented. When purchases are made from

farmers or other collectors known to operate only

locally, a statement capable of verification will be required as needed for proof of origin.

3. To require an accurate record of the origin

of all lots of seed and nursery stock used in forest,

shelterbelt, and erosion-control planting, such records

to include the following minimum standard requirements to be furnished with each shipment:

( 1 ) Lot number.

(2) Year of seed crop.

(3) Species.

(4) Seed origin: State—County—LocalityRange of elevation.

(5) Proof of origin.

4. To use local seed from natural stands whenever available unless it has been demonstrated that

seed from another specific source produces desirable

plants for the locality and uses involved. Local seed

means seed from an area subject to similar climatic

influences and may usually be considered as that collected within 100 miles of the planting site and differing from it in elevation by less than 1,000 feet.

5. When local seed is not available, to use seed

from a region having as nearly as possible the same

length of growing season, the same mean temperature

of the growing season, the same frequencies of summer droughts, v^th other similar environment so far

as possible, and the same latitude.

6. To continue experimentation with indigenous

and exotic species, races, and clones to determine their

possible usefulness, and to delimit as early as practicable climatic zones within which seed or planting

stock of species and their strains may be safely used

for forest, shelterbelt, and erosion-control.

7. To urge that States, counties, cities, corporations, other organizations, and individuals producing

and planting trees for forest, shelterbelt, and erosioncontrol purposes, the expense of which is borne wholly

or in part by the Federal Government, adhere to the

policy herein outlined.

IVHERE TO PURCHASE SEED

A partial list of tree-seed dealers in the United

States and a few foreign countries can be obtained by

writing to the Forest Service, U.S. Department of

Agriculture, Washington, D.C., 20250.

A list that includes tree-seed dealers in the Plains

States and dealers who handle seed native to the

Plains States can be obtained from the Rocky Mountain Forest and Range Experiment Station, Colorado

State University, Fort Collins, Colo.; and the Lake

States Forest Experiment Station, St. Paul Campus,

University of Minnesota, St. Paul 1, Minn.

U.S. GOVERNMENT PRINTING OFFiCE : 1965 O—748-005