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DIRECTSEEBiNG PINES

Harold J. Derr qnd Williatfi F^ Mann, Jr.

U.S. DEPARTMENT OF AGRICULTURE • FOREST SERVICE • AGRICULTURE HANDBOOK NO. 391

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9l)L 1 8 1991

DIRECT-SEEDING PINES IN THE SOUTH

Harold J. Derr and William F. Mann, Jr.

AGRICULTURE HANDBOOK NO. 391

U.S. Department of Agriculture Forest Service

Issued April 1971

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

Washington, D.C. 20402 - Price 65 cents

CONTENTS

Direct seeding in southern pine

management 2

Seeding situations 3

Plant or seed? 7

Natural or artificial regeneration? 10

Choice of species 13

Longleaf pine 13

Loblolly pine 14

Slash pine 16

Shortleaf pine 17

Virginia pine 19

White pine 19

Site and seedbed preparation 22

Prescribed fires 22

Disking 24

Furrowing 26

27

28

Site clearing

Site amelioration

Direct-seeding techniques 29

Seed procurement 29

Seed storage and testing 33

Stratification of seed

Coating seed with repellent

Time of sowing

Sowing rates

.33

-35

-.39

..40

Distributing seed —^ground methods 41

Aerial seeding 44

Calibrating seeding equipment 49

Protecting seed and seedlings 51

Birds 51

Small mammals 52

Large animals 54

Livestock 54

Insects 55

Disease 58

Weather 58

Appraisals 58

Estimating predator activity before

and during germination 59

Seedling inventories 60

Literature cited 62

111

DIRECT-SEEDING PINES IN THE SOUTH

by

Harold J. Derr and William F. Mann, Jr/

Direct seeding of the southern pines is a

versatile reforestation technique that is being

widely accepted by land managers. On many

sites it is more economical than planting

nursery-grown seedlings or waiting for natural

reproduction. It is applicable on some sites

where access, terrain, or drainage conditions

make planting difficult. Commercial trials have

proved it fast and reliable with all the important

southern pines and in operations ranging from

a few acres to units of 35,000 acres (68).^

While the technique for direct seeding is new,

the basic concept is not. For more than a century, foresters throughout the world have been

intrigued by the apparent ease and simplicity

of starting stands by sowing limited quantities

of seed at the right time on a suitable forest

seedbed. Through the years pioneers in the regeneration of southern pines conducted sporadic

trials, but their occasional successes were far

outnumbered by failures. Usually work was

stopped after a few setbacks. The early attempts clearly showed, however, that seed

depredation by birds and rodents was the biggest obstacle.

In 1947, scientists of the Southern Forest

Experiment Station began a concentrated, continued effort to make direct seeding a reality.

The research, which was centered at Alexandria, La., was aimed chiefly at finding a practical method of protecting seed from birds.

^ Silviculturist and principal silviculturist, respectively, at the Southern Forest Experiment Station's

field headquarters at Alexandria, La.

* Italic numbers in parentheses refer to Literature

Cited, p. 62.

since in the South both resident and migratory

species are usually numerous when pine seed is

sown. Rodents, though a problem, were regarded as easier to cope with. Ways of improving and speeding germination were studied with

a view to reducing the time seed is exposed to

predators and weather. Information was also

sought on the best seasons for sowing the various species and on methods of seedbed preparation.

The first breakthrough came in 1953, when

sublimed synthetic anthraquinone and an imported commercial repellent containing anthraquinone were found to be effective, nontoxic

bird repellents. In the first successful field

demonstration of a chemical bird repellent,

longleaf pine (Piniis palustris Mill.) seeds

coated with the commercial preparation and

sown at the rate of about 12,000 per acre

yielded 4,500 seedlings in contrast to 195 for

the uncoated seeds (70), Birds destroyed most

of the untreated seed within 10 days.

In the next few years, thiram formulations,

as well as several more anthraquinone compounds, were also found to protect seed from

birds. By the fall of 1957, a seed coating that

was repellent to birds, rodents, and many insects had been thoroughly tested. Pilot trials

were undertaken immediately by industrial

landowners, mostly in Louisiana where the research had been done. Pioneer operations succeeded so well that 75,000 acres were sown in

the State during 1959—only 2 years after the

first operational seedings (67), The practice

quickly spread to other parts of the South, and

within 10 years almost 1 million acres were

direct-seeded. The recommendations developed
initially have proved basically applicable in all

parts of the region and to the major southern

pine species.

This handbook summarizes information from

intensive research and operational direct seedings made under a broad array of conditions

within the South. It includes published and unpublished information that has accumulated

from 20 years of research and usage. Undocumented statements represent the best opinion

of qualified observers with wide practical experience. The first section is intended largely

for the land manager who makes policy decisions. It describes site conditions under which

seeding is or is not feasible, and it weighs the

alternatives of seeding, planting, and depending

upon natural regeneration. Following sections

provide detailed information for those who v^dll

be planning, executing, and evaluating a direct

seeding. Experience has been greatest with

longleaf, loblolly (Pinus taeda L.), and slash

pine (P. elliottii Engelm.) ; but enough work

has been done with shortleaf (P. echinata Mill.)

and Virginia (P. virginiana Mill.) pine to permit firm recommendations. Because it has been

seeded in the southern Appalachians, white pine

(P. strohus L.) is also discussed. Careful adherence to prescriptions is suggested, especially

in early trials for consistent success with this

reforestation technique.

DIRECT SEEDING IN SOUTHERN PINE MANAGEMENT

Direct seeding should be regarded as another

technique, along with planting and natural regeneration, for restoring depleted forests and

for restocking lands promptly after cutting. As

such, it affords the manager substantially more

flexibility and, in many situations, greater economy in maintaining full productivity of his

forests than he had previously. Rising costs for

-planting, an increasing shortage of labor, and

the demand for prompt restocking to insure

maximum timber production all are reasons for

giving this technique careful consideration.

Landowners have shown great imagination

and ingenuity in adapting direct seeding to

many situations. It has been effective from Virginia to Texas, in the mountains and in the

Lower Coastal Plain, on wet and dry sites, on

lands with heavy grass sods or with dense

stands of worthless hardwoods, on areas where

seed trees failed to restock pines, and on sites

with heavy debris from salvage cutting of

stands damaged by fire or storm. Landowners

of all types have used it, and several firms seed

on contract and guarantee stocking.

A few landowners have switched completely

from planting to seeding. Others believe planting is the better method for attaining their objectives. Most are using both techniques to

maximum advantage by fitting each to situations where it is best suited.

Direct seeding is as reliable as planting when

operations are executed according to recommendations. Most of the failures recorded over

the last 10 years were due to human error. Use

of poor seed, sowing too late, and attempting to

seed sites on which planting had failed repeatedly have been major reasons for avoidable

failures. Unfortunately, some landowners have

judged seeding on hearsay from these trials,

without learning the full reasons for the outcome. In other instances, managers have

marked off their own efforts as failures when

casual inspection (instead of systematic inventories) appeared to indicate an inadequate

stand. Dozens of seeded areas have been planted

before it was recognized that their stocking was

already adequate. The only way for a manager

to appraise the reliability of seeding is to conduct trials on his own land, making certain all

recommendations are followed precisely.
Seeding Situations

Sites that can be seeded advantageously are

numerous and extensive in the South. Practically speaking, they fall into tvs^o classes: open

lands and those partially or wholly occupied by

brush or low-value hardwoods.

Open lands with heavy grass sods (fig. 1),

found predominantly in the Lower Coastal

Plain, are often seeded with loblolly, slash, or

longleaf pines {,2U, 71,72). Such sites are relatively inexpensive to plant, but the speed of

seeding large acreages has prompted many

operations. Most longleaf pine has been sown

on these sites. As longleaf is difficult to plant,

seeding is the most practical means of reforestation.

Included in the category of open sites are

abandoned fields and land on which timber has

recently been clearcut. Normally, these sites can

be seeded after a preparatory burn to reduce

surface litter.

Direct seeding has also proved useful in restocking stands destroyed by wildfire and windstorms. Salvage cutting scarifies the soil, creating an excellent seedbed. Tops, stumps, and

other impediments to planting are no obstacle

to aerial seeding (fig. 2). Thousands of acres

throughout the region have been regenerated

in the same year in which their stands were

destroyed {16).

Many open areas are on sandy flatwoods sites

in the Atlantic and Gulf Coastal areas. Soils are

wet most of the year, and a high water table in

winter seriously impedes planting. These are

among the easiest seeding chances, because

there is ample soil moisture for germination

and first-year survival. Outstanding results

have been achieved on large tracts with no

more site preparation than is needed for planting. If there is a medium to heavy growth of

gallberry and palmetto or a dense sod of native

grasses, disking or furrowing after burning

usually improves survival and early growth.

This is especially true for loblolly and slash

FS-81897a

Figure 1.—Cutover sites with dense grass sod have been sown extensively v^ith longleaf, slosh, or loblolly pine.
pine ; if palmetto and gallberry are sparse, longleaf normally can be seeded on open sites without mechanical preparation.

Lands occupied by brush and hardwoods predominate in the South. They include a tremendous range of stand conditions—from cull

stands of commercial species to dense thickets

of low-value species and shrubs such as myrtle,

gallberry, and titi. Some of the cover variations

are due to regional differences in soils, drainage, and species composition; others are the

result of previous management and fires.

Throughout the Lower Coastal Plain, pines

have been sown extensively on sites preempted

by low-value hardwoods (fig. 3). Grasses, which

would compete vigorously with seedling pines,

are largely shaded out by the hardwood canopy.

Where the hardwoods are large, mechanical

site preparation is unnecessary; individual

stems are deadened soon after the pines germinate. Seeding has rarely failed on these sites.

Sites with small, dense hardwoods are more

costly to regenerate, but they do not involve

any greater risk. Usually the hardwoods are

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Figure 2.—Salvage cutting of pine stands destroyed by fire often leaves so much debris that aerial seeding is the best method of

reforestation.
destroyed in advance of sowing by chemical

sprays or mechanical treatments like chopping,

disking, or shearing. Mechanical control of the

brush also prepares a seedbed ; burning may be

necessary when foliar sprays are used. Heavy

debris from hardwood control does not hinder

aerial sowing. In contrast, windrowing is often

necessary before machine planting.

In the Southeast, titi flats and pocosins with

heavy brush (ñg. 4) are being seeded with

consistent success (fig. 5) ; high water tables

provide ample moisture for seedling establishment and survival. Mechanical reduction of

hardwoods followed by hot fires gives sufficient

site preparation for seeding. Debris from the

hardwoods, a wet organic layer 12 inches or

more deep, and thick masses of roots just below

the surface make these sites difficult and costly

to plant.

Stands of cull hardwoods in the Piedmont and

the mountains of Georgia, Tennessee, and Ar-

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Figure 3.—Upland pine sites occupied by low-value hardwoods can

easily be seeded to pine. Hardwoods must be deadened soon

after pine germination is complete. (Photo by Louisiana Forestry

Commission.)

kansas have been converted to pine in largescale seeding operations. They are treated like

similar areas in the Coastal Plain, although

soils are often rocky and the terrain is steep

(fig. 6). Since dense, small hardwoods usually

are present also, heavy machinery has been used

for site preparation in advance of sowing (38).

In Alabama, direct seeding has been successful on spoil banks left after strip mining (Fig.

7). The steep, rocky slopes are almost impossible to plant. Sowing at normal rates has given

good stands of loblolly, shortleaf, Virginia, and

longleaf pines. Even embankments with slopes

of 70 to 80 percent have been reforested; apparently many seeds become lodged behind

stones and in crevices that prevent them from

washing away. Seeding has been more successful on fresh spoils than on those left for 5 or 6

years, probably because competing vegetation

is absent. However, low soil pH has caused

planting and seeding failures on some spoils

where overburden from just above the coal

seam was put on top of the banks.

On substantial acreages in the South, heavy

clays compose the surface soils. They are virtually impossible to plant either by machine or

hand; problems are encountered both in opening and closing a slit for the trees. These sites

are readily seeded, and survival is usually high

because the soils have excellent moisture-holding

capacity.

Some soil or terrain conditions are unsuitable

for direct seeding or require special treatment.

Most prevalent, perhaps, are localized tracts of

deep upland sands whose surface dries so

rapidly that moisture is inadequate to sustain

germination of broadcast-sown seed (fig. 8). On

these sites, seeds must be covered with l^ to %

inch of soil (39, i3, 75, 92).

In addition, there are general areas where

recurrent droughts or soils with poor moistureholding capacity make pine regeneration difficult to achieve by any means. In such places,

notably the extreme western portion of the

southern pine belt, planting probably is more

reliable than seeding.

Sowing should not be attempted on steep

slopes if soil or cover conditions allow excessive

washing of the seed in heavy rains. Slopes of 30

to 40 percent ordinarily are not too steep even
FS-SI8973

Figure 4.—In the Southeast, heavy stands of saw-palmetto, gallberry, and t!t! must be reduced with machines and then burned before

pines are seeded.

where erodible soils are relatively bare. On

more stable soils, especially those with some

cover to hold seed in place, and on spoil banks,

slopes up to 80 percent have been seeded successfully. Finally, sowing should not be attempted on poorly drained sites where the seed

or seedlings will be under water for more than

1 or 2 weeks (60, 78). Practical means of preparing wet areas include drainage, elevating

seedbeds by disking, or creating artificial tussocks. In some situations, sowing can simply

be deferred until danger of seasonal submergence is past.

In summary, sites suitable for direct seeding

include most of those available for commercial

pine production in the South. Among these

sites there are wide variations in soil and cover

conditions. Usually some site preparation is
F5-5I8973

Figure 5.—Wet coastal sites support dense titi (right) that must be destroyed with herbicides and fire before pines can be seeded. Slash

pines at left are 3 years old. (Photo by Buckeye Cellulose Corporation).

needed; it may vary from intensive treatment

that is essential for survival and growth to

simple methods used primarily for increasing

the probability of getting adequate stocking.

Plant or Seed?

Most of the sites described above can be

planted or seeded with equal reliability. Why

then choose seeding ? There are two compelling

reasons: lower costs, and a growing shortage

of labor.

Costs of broadcast seeding vary by species

and site conditions, ranging from about $4 to

$8 per acre. The price of seed is the big item

of expense, and many companies have cut costs

substantially by collecting their own seed. Reports of row seeding (done with machines that

prepare seedbeds and sow simultaneously)

sometimes quote costs of about $3 per acre,

primarily because less seed is required than for

broadcast sowing. Of course, outlays for equipment are greater for row sowing than for sowing done with aircraft. None of these prices

include hardwood control, which generally costs

the same for seeding as for planting.

As a general rule savings from seeding are

greatest where planting costs are highest. Differences average from $3 per acre on welldrained, open land to $15 or $20 per acre on

rough sites where debris from hardwood control would slow down planting crews. Though

seedbed preparation and control of hardwoods

are the same for both methods in most situations, there are two major exceptions. First,

disking is often needed before seeding on welldrained grassy sites, whereas pines can be

planted directly in the rough. Second, felled

hardwoods must be windrowed to allow movement of planting machines, while sowing can be

done without this added expense.

Seeding has economic advantages in addition

to lower direct costs. Large capital outlays for

supplies and equipment are unnecessary (-^9).

Contractual services are available for seed procurement and treatment, and for sowing. Then,

too, large tracts can be seeded so rapidly that

supervisory personnel are freed for other duties

in a relatively short time.

Labor is becoming scarce. In many places, it

is no longer possible to obtain hand crews for

planting large tracts that are too rough for
FS-51a974

Figure 6.—Direct seeding is effective in regenerating steep, rocky sites such as this one in north-central Alabama. The pines are longleaf.

machine planting. In consequence, many com- of the number of trees per acre justifies the

panies with long-standing planting policies have higher costs of planting, since stocking influbeen forced to start seeding. enees tree size and time of first thinning. Moreover, well-defined rows are desirable for The major objections to direct seeding are

that it gives less control of stocking than does mechanical harvesting systems, which are gaining acceptance in the South. planting, and that trees are not established in

rows when sowing is by broadcast methods. These reasons are valid. It should not be overMany forest managers believe that regulation looked, however, that stocking can be partially

8
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FS-5I897S

Figure. 7.—Spoil banks left from strip mining con be seeded readily.

The growth of seeded and planted trees has

controlled by adjustments in sowing rate, al- often been compared and, though data are limthough not so precisely as in planting. Row and ited to young stands, there is no evidence that

spot seeding are alternatives for those who the densities commonly achieved in direct seedwant trees in well-defined array (fig. 9). ing afl'ect growth and yield {28, 3i, 4-7, 50, 80).
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FS-S18977

Figure 8.—Localized upland areas of deep, sterile sand are difficult to seed—or to plant. If seeding is attempted it should be

done wi»h machines that cover the seed.

Much tree improvement work is in progress,

and in coming decades seed orchards will produce quantities of seed from selected superior

trees (106). Will such seed be too scarce and

expensive to use in direct seeding? It is doubtful that all production anticipated from

orchards already established can be used in

planting. Some form of spot or row seeding

may be feasible. Possibly the elite seed can be

mixed with some of lower quality, for if the

seedlings from elite sources are truly superior

they will dominate the stand. The others will

be readily identifiable and can be removed whenever they have served their purpose as fillers.

Natural or Artificial

Regeneration?

Artificial regeneration is becoming more important in the management of southern pine

forests as the demand for wood increases. Consequently, greater effort will be expended to

increase productivity on existing ownerships.

Acquisition of new lands, the usual recourse in

the past, will slow down because the acreage for

sale is comparatively small and prices are high.

Silvicultural systems aimed at securing natural regeneration have been used widely

throughout the South. The seed tree, shelterwood, selection, and strip-cutting systems have

all been tried. Where summer rainfall is abundant, seed crops are frequent, and trees are not

f^-^n^'^ii'^ß'^ ' -'• ^ *!.'-"

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FS-5IS97e

Figure 9.—These 3'/2-year-old longleaf pines demonstrate that row

seeding gives good control of stocking.

harvested until they are over 50 years old,

natural regeneration will be relied upon for a

long time. But these conditions are lacking in

much of the region. In the middle and western

portions, summers tend to be dry and some

areas have not had a seed crop in 12 years.

Furthermore, as management intensifies, the

average rotation may be shortened to less than

50 years.

Natural regeneration is not always obtained

cheaply or easily, especially by the seed-tree

and shelterwood methods. Lightning, wind, and

insects take a steady toll of the reserved trees

(fig. 10), and since these are usually choice

stems the loss of even a few per acre is costly.

Harvest of the seed trees often damages the reproduction, and stumpage prices are usually

less than for trees cut initially.

The success of natural regeneration hinges

primarily on early occurrence of a seed crop.

While crops fail or are delayed, sites remain

unproductive, seedbed scarification from logging rapidly disappears, and dense brush may

develop. The presence of seed trees also limits

the intensity of fires that may be set for hardwood control and hampers mechanical control.

During this unproductive period, taxes and

management costs continue.

Naturally seeded stands are often patchy,

with densely stocked and open areas interspersed. It is very difficult to fill the voids, and

precommercial thinning is the only means of

10
FS-518979

Figure lO.-Notural regeneration area with about eight loblolly seed trees per acre. While the forester awaits a seed crop, brush is

invading the site and a high-quality tree has been killed by lightning.

11
regulating the overdense patches. If a bumper

seed crop occurs immediately after logging,

stands may contain as many as 20,000 pines

per acre (fig. 11).

Many landowners have already recognized

the shortcomings of natural regeneration and

have started to liquidate seed trees, prepare

sites, and restock pines by artificial means. In

many parts of the South, natural regeneration

probably is doomed to disappear as lands are

managed intensively to obtain the full growth

potential.

^'•;#vS':»i''''*

F5-E18980

Figure 11.—Little control of stocking is possible when stands are regenerated naturally. Here slash pine seed trees have produced a

stand averaging 12,000 trees per acre.

12
CHOICE OF SPECIES

Choice of the best species is difficult on some

sites; on others one species is clearly superior.

In the coastal flatwoods, for example, slash pine

has proved to be best suited. On the Upper

Coastal Plain, where terrain is rough and hardwood competition is aggressive, loblolly pine is

best. But there are broad areas where both

species grow well on the same sites and where

longleaf pine can also be used. Where there is

a choice, the best course is to take the species

that is superior in growth and yield. This is generally safer than following the oft-repeated rule

of using the species that formed the original

stand. Management problems such as disease,

wildfire and unrestricted grazing are sometimes

considered in selecting species.

On occasion, a mixture of two species has

been sown, generally in the hope that if one

failed the other would provide adequate stocking. Slash-loblolly mixtures have been tried,

but with no clear advantage over either species

alone. Conceivably, mixtures of loblolly and

shortleaf and of loblolly and Virginia pine also

could be used, but it is doubtful if the stands

would excel those of a single species carefully

selected for the site. Good separate stands of

two species have been established adjacent to

each other within fairly small areas. For example, longleaf has been seeded on upland

ridges and slash pine has been planted on the

interspersed lowlands where seeded longleaf

does not compete well with dense grasses and

sedges.

Basic direct-seeding procedures do not vary

greatly from species to species. The same repellent formulation can be used, sowing methods

are essentially alike, and all but one of the six

species discussed here should be sown in the

same season. There are, however, species differences in fruiting habits, seed size, seed

dormancy, and site requirements. These and

other relevant species characteristics are discussed in the following sections.

Longleaf Pine

Because it germinates rapidly and in cool

weather, longleaf is often regarded as the

easiest species to seed. It can be sown in the fall.

when moisture in the surface layer of soil is

less variable than in the spring. Fall-germinated

longleaf seedlings survive early summer

droughts better than seedlings that germinate

in spring. Spring sowing is preferable, however, where danger of frost heaving or other

winter damage is great.

Longleaf produces large quantities of seed

at intervals of 3 to 5 years, and somewhere

within the species' range there is a collectable

crop nearly every year {101), Cones are easy to

gather; yields of 10 bushels or more per tree

are common in good years. Seeds are the largest

of the southern pines and the least expensive

when collected in quantity. Partially dewinged,

they average about 4,500 per pound. They are

never dormant, even after storage.

In planning for direct seeding, several characteristics of longleaf should be considered.

First are its site requirements {99), While it

does well on a wide variety of soils, its survival

and early growth are best on well-drained sandy

loams and sandy clay loams (fig. 12). It does

not tolerate the dense herbaceous competition

common to many poorly drained sites, and it

requires prompt and complete release from

overstory hardwoods.

A second important characteristic is its need

for intensive protection and management during its grass stage—normally 3 to 6 years. It

must be fully protected against hogs, sheep, and

goats ; and grazing by other animals should be

regulated {1Í, 62). Within their respective

ranges, Texas leaf-cutting ants (tov^ ants)

and pocket gophers favor well-drained sites

where longleaf pine is most likely to be used.

These pests must be controlled before longleaf

can be established. Most seedling stands require

one or more prescribed burns for control of

brown-spot needle blight, caused by the fungus

Scirrhia acicala (Deam.) Siggers. Longleafs

early tolerance of fire is an advantage in areas

where the incidence of wildfires makes other

species a risky choice.

The natural range of longleaf pine extends

from Virginia to Texas and from the Gulf of

Mexico to the mountains of north Alabama.

The Southwide Pine Seed Source Study, which

was undertaken during the early 1950's, has

13
FS-5189al

Figure 12.—Aerially seeded longleaf starting height growth on an open, well-drained site.

shown that within this range there is substantial genetic variation associated with physiography and climate, and that some geographic sources are superior in specific planting

zones (103).

Loblolly Pine

Its wide geographic distribution and adaptability to a broad array of sites—in particular

those on which hardwoods are aggressive—

make loblolly pine the most widely sown species

(fig. 13).

Loblolly pine stands produce seed abundantly,

but with somewhat less frequency than either

longleaf or slash pine. Cones are most difficult of the three to collect; consequently, seed

costs are highest. Cleaned, dewinged seed averages about 18,500 per pound.

With few exceptions, fresh or stored lots of

seed are dormant and require stratification for

maximum field germination (57). Unlike longleaf, unstratified loblolly seed does not germinate during fall or winter. Fall-germinated

seedlings from stratified seed are often destroyed by freezing weather. Though fall sowing of unstratified seed for spring germination

is possible, a more effective course is to break

dormancy through artificial stratification, then

sow in the spring when temperatures are reaching levels needed for germination (71). Juvenile

seedlings are sensitive to drought in late spring

or early summer but develop considerable tolerance of drought later in the summer. They are

relatively intolerant of competition from dense

grass or low brush ; in fact, seeding loblolly is

seldom advisable without some form of site

treatment, such as disking, to reduce competition.

Within the main part of its range, loblolly is

adapted to most sites capable of supporting

pine. In many situations, management is not as

demanding as for longleaf, though loblolly requires complete fire exclusion for the first 5 to

10 years. It grows best in soils with poor surface drainage, a deep surface layer, and a firm

subsoil (99). It is a questionable choice for dry

ridgetops, such as those occurring throughout

the original range of longleaf pine, and on

poorly drained soils having a hardpan (fig. 14).

It can be established on these sites, but growth

14
FS-5I898Z

Figure 13.—Loblolly pine can be reliably seeded on sites dominated by cull hardwoods.

or tree form may be poor. Loblolly is attacked

by the Nantucket tip moth {Rhyacionia fnistrana (Comstock)) and the southern fusiform

rust (Cronartium fusiforme Hedge. & Hunt ex

Cumm.). Both may be locally severe, and adverse sites tend to increase the hazard, particularly from tip moth. As neither pest can be

controlled economically, each is a factor to be

considered before loblolly is chosen for areas

v^^here it is not a prevalent species or for specific

sites where it does not occur naturally.

Geographic variability within the broad range

of loblolly pine has been recognized for many

years ; thus, all sources of seed are not equally

adapted to a particular locality {101). Tenyear results from the Southwide Pine Seed

Source Study have shown tentative possibilities

for maximizing growth, survival, and fusiformrust resistance by moving seed beyond local

zones {103, lOU). Forest managers who must

utilize nonlocal seed should review carefully the

latest reports of the Committee on Southern

Forest Tree Improvement, which is sponsoring

the Southwide Study.

as
Figure 14.—Loblolly pine (left) does not grow as well as slash (right) on poorly drained soils having a hardpan layer. These planted trees

are 9 years old.

Slash Pine

Slash pine was the last of the three major

southern pines to be used extensively in direct

seeding, though for no clearly apparent reason.

It is easy to start from seed, and many good

stands have been established (fig. 15).

Some seed is produced within the slash pine

range nearly every year, and cones are collected

readily from standing trees. Consequently, seed

costs are moderate, generally about midway between those for longleaf and loblolly seed when

all three are available in commercial quantities.

Cleaned, dewinged seeds average about 13,000

per pound. Seeds vary in their requirements for

stratification. Some lots do not need it; others

benefit.

If soil moisture is adequate, seed will germinate during warm periods in the early fall.

Usually only a fraction of the sown seed germinates, the balance overwintering until late

February or March. Spring sowing is favored

in most places because fall germination is unpredictable and a winter-long delay reduces

eifectiveness of the repellent coating. In the extreme southern portion of the Gulf Coast States

temperatures are high enough so that germination can usually be expected throughout the

winter, and here fall sowing is recommended

(72).

Juvenile seedlings grow rapidly, developing

tall, succulent tops early in spring. They are

sensitive to early droughts, and therefore benefit greatly from site preparation treatments

(88) that reduce competition, conserve soil

moisture, and permit rapid root development

(fig. 16).

Slash pine is versatile. It has been planted

and seeded on dry, sandy ridges as well as on

heavy, poorly drained flatwoods soils. It is, perhaps, the best species for soils having a shallow

claypan or hardpan, slow internal drainage, or

a high water table. It has been used extensively

outside its natural range, especially on former

longleaf sites west of the Mississippi River.

Northward extension of its range is limited

principally by susceptibility to stem breakage

in ice storms. Like loblolly, it is very susceptible

16
PS-SIS984

Figure 15.-Seeded slash pine grows rapidly on many sites. These are 5-year-old trees on wiregrass-polmetto land in Georgia.

to fusiform rust, but it is resistant to tip moth

attack and thus has been favored for areas

where this pest abounds.

Of the two recognized varieties, var. densa

does not thrive in continental United States outside its limited natural range in south Florida.

Typical slash pine, var. elliottii, has the smallest natural range among major southern pines.

There is apparently continuous variation in

Florida between variety densa in the south and

variety elliottii in the north. The result is that

genetic potential for fast growth and good survival decreases the farther south seed is collected in peninsular Florida {96). Several old

seed-source plantings within the natural range

of the species have shown that there is little

geographic variation in volume growth, rate

of infection by fusiform rust, or oleoresin production {8, 23, 93) among trees grown from

seed collected along an east-west transect

through the slash pine range from South Carolina to Louisiana. If plantings are planned very

far outside of the slash pine natural range, however, seed from northern Florida and southern

Georgia has less potential for growth and survival than seed from Mississippi, Louisiana, or

South Carolina. The caveat also applies if seed

is to be collected in old slash pine plantations, as

practically all of them established before 1940

and many even later were from seed collected

in northern Florida or southern Georgia {93).

Shortleaf Pine

Shortleaf pine has been seeded mainly in the

northwestern part of its range, where it is the

principal coniferous species. In the large Midsouth region where shortleaf and loblolly pine

are associates on many sites, landowners favor

loblolly. There are many reasons for their

choice; from the standpoint of direct seeding,

cost and availability of seed are the main ones.

Though shortleaf has exceptionally heavy seed

crops periodically, its cones are small and difficult to collect. Cleaned, dewinged seeds average

about 45,000 per pound. They resemble loblolly

in many of their characteristics—they normally

germinate in the spring, they tend to be dormant, and they respond to stratification.

Shortleaf is a wide-ranging species, both

geographically and among the many site conditions that occur within its range. Its best

growth is on silt loams or fine sandy loams

with good internal drainage, found mainly in

17
PS-5IS98S

Figure 16.—Site preparation enables slash pine seedlings to extend their roots rapidly and thus achieve a measure of protection against

early drought. These 3-month-old seedlings had roots more than 10 inches long.

18
the flood plains of small streams (99). Hardwood competition is a common problem in

shortleaf pine seeding. If soil moisture is critical, seedlings may benefit from shade during

their establishment period, but they require

release fairly soon after that (82, 99), Shade

is not prerequisite, however, and stands have

been established on sites completely cleared in

advance of sowing. As with most broadcast

seeding of pine, exposed mineral soil is needed

for maximum catch.

Shortleaf is commonly regarded as droughtresistant, possibly because it colonizes dry sites

where other species fail. The ability of young

trees to sprout vigorously after a fire also helps

perpetuate it under adverse conditions. It is

relatively immune tc fusiform rust, but is attacked by tip moths and bark beetles (99), On

heavy soils in some parts of the range, littleleaf disease has discouraged use of shortleaf

pine in all forms of stand regeneration.

North-south geographic variation in shortleaf

pine growth has been suspected for many years.

These impressions have been confirmed by the

Southwide Pine Seed Source Study, and seedcollection and planting zones have been proposed to enable land managers to take advantage of the inherent geographic variation in the

species (103),

Virginia Pine

Virginia pine was long regarded as a lowvalue tree because of its poor form and persistent branches (fig. 17). Its ability to colonize

and grow on impoverished sites and to produce

pulpwood on short rotations has generated interest. Direct seeding is appealing because many

of the sites to which it is suited are rocky and

steep, hence difficult to plant. Seed is abundant

because good crops occur frequently. Occasionally, there are good crops in two successive

years, and normally some seed is produced

every year (98), Cones and seeds vary greatly

in size; the number of seeds per pound range

from 40,000 to 78,000, averaging about 45,000.

Virginia pine is unique among southern pines

in that its seeds become viable at least 2 months

before the cones open. Viability is indicated by

a change in color of the cones from green to

dark purple, and usually occurs in September.

For cones collected at this time, however, a

period of afterripening storage improves viability (29), Seedfall normally starts in late

October and continues for approximately 3

months.

The seed normally germinates in the spring

following seedfall. It is not as often dormant

as loblolly pine seed, but some lots respond to

stratification, and hence all lots should be routinely tested for dormancy. Delayed germination

has been observed on several seedings, often

until summer droughts ended in July or August

of the first year (95), Apparently, the seed can

maintain its viability through dry weather.

Virginia pine has been described as a disaster

species, since it readily invades areas denuded

by fire, storm, or cutting. It grows well on a

variety of soils, but does best on well-drained

clay, loam, or sandy loam soils. It readily invades impoverished sites such as eroded old

fields, and is commonly the prevalent species on

the poorer ridgetops, especially on soils derived

from shale (99),

Virginia pine is intolerant, especially to overhead competition for light. That successful

direct seeding requires fairly intensive site

preparation was indicated by a series of 23

trials in West Virginia (9I^, 95), In these, various sites were prepared by methods that gave

several degrees of competition control. Best

results were achieved with treatments that

eliminated grass sod as well as woody vegetation. On the Cumberland Plateau in Tennessee,

Virginia pine can be seeded beneath hardwoods,

where grass is sparse (32), Complete control

of competing hardwoods in the first year is

essential on such sites.

White Pine

Direct seeding of eastern white pine in the

southern part of its range—the southern Appalachians in North Carolina, Tennessee, and

Georgia—has been limited mainly to small

trials. White pine has a good seed crop at intervals of 3 to 5 years (99), but lapses of 10 or

more years may occur locally if attacks of cone

insects are heavy or weather is adverse (59),

Cleaned seeds average 27,000 per pound. They

require prolonged stratification for optimum

germination; 30 to 60 days or more is recommended (18, 31), Seed can be stored for 10

years or more (8^),

19
FS-518986

Figure 17.—Virginia pine has poor form, but is a good pulpwood species on many sites. This 5-year-old stand was established beneath

hardwoods, then released.

20
Much of the effective direct seeding in the

northern part of the white pine range has been

done on scarified spots, usually with soil covering the seed. Fall sowing of unstratified seed

has been favored {2, 3, 5). Spring sowing of

stratified seed has been effective in the southern

Appalachians, and in at least one trial maximum germination (75 to 80 percent) resulted

from a soil covering of 14 to 1 inch Ul).

In the southern Appalachians, white pine

grows at 1,200 to 3,500 feet above sea level, and

is generally restricted to northerly aspects,

coves, and stream bottoms. The ideal seedbed

has been described as one with exposed mineral

soil, roughened surface to facilitate seed coverage, and a light plant cover to cast patchy

shade (59). Complete removal or drastic reduction of hardwood competition is considered

essential, and old-field sites are not regarded

as good seedbeds after heavy grass sods develop.

Seedlings benefit from low shade during the

establishment period, but later respond to full

release.

Initial growth of seedlings is slow. On the

Cumberland Plateau, 4-year-old trees from seed

were as tall as planted seedlings of the same

age (87). In this test satisfactory stocking was

achieved by broadcasting about 10,000 full

seeds per acre in early April on a hardwooddominated site that had been scarified with a

light disk (33). Much of the experimental work

indicates that this relatively tolerant species

may be better adapted for stand conversion

than to the harsher conditions found on abandoned fields or on completely cleared sites (fig.

18).

^

W

W;~, :,- »> /^.itfeis

FS-5IS9S7

Figure 18.—Eight-year-old white pine that was seeded in Tennessee on a site dominated by low-value hardwoods. , ,

21
SITE AND SEEDBED PREPARATION

Selecting sites that can be seeded to pine and

choosing presowing treatments are closely related planning tasks. Sites cannot be judged

without considering the cost, time requirements,

and silvicultural effects of the treatments

needed to put them in shape. Methods vary in

cost and intensity, but in most cases conditions

on the site determine the method that must be

used. Undertreating a site is more common

than overtreating, for it is easy to overestimate

the long-range effect of a single treatment—

especially on sites with aggressive, fast-growing

weed hardwoods. Increasing demand for land

and raw materials is moving pine regeneration

efforts onto sites heretofore neglected because

of adverse terrain or preemption by worthless

and low-value species. Such sites require expensive preparation, whose justification or longrange impact on land and timber values is

beyond the scope of this handbook.

Site preparation has two objectives, usually

achieved concurrently: to expose the mineral

soil that pine seeds need for germination, and

to control competing vegetation that will interfere with the survival and early growth of the

new stand.

Fire is the simplest and least expensive

method of site preparation, and on open sites

it is often sufficient by itself. On areas with

hardwood trees or brush, it is combined with

mechanical treatments like disking, chopping,

or shearing. Whatever means are chosen, fairly

complete removal of competing hardwoods is

usually requisite, even where the trees occur

in groups and pine seeding is restricted to openings. All southern pines, including Virginia

pine, can be established beneath hardwoods, but

none can survive much beyond the first year

without considerable mortality and loss of

vigor. Figure 19 and table 1 illustrate the point

for loblolly pine, which is relatively tolerant of

hardwood competition. In appraising a hardwood-dominated site, the likelihood of sprout

growth must be considered. If the trees are

large enough to be treated individually with a

chemical, sprouting is not likely to occur. But if

a dense stand of small stems is treated superficially, as by light disking or single chopping,

sprouts may develop rapidly and in such abundance as to overwhelm the pine seedlings.

Table 1.—Ejfect of time of release on survival and

height of seeded loblolly pine ^

Survival after—- Height a

1 2

fterTreatment 1 2 3 3

yr. yrs. yrs. yr. yrs. yrs.

Seeded February 1959

Released May 1959

Released April 1960

No release

Pet.

51

58

57

Pet.

43

45

46

Pet.

35

37

36

In.

5

3

3

In.

13

7

4

In.

31

23

7

Seeded February 1960

Released May 1960

Released April 1961

No release

72

58

59

51

48

50

39

41

33

5

3

3

17

9

5

39

25

9

Seeded February 1961

Released February 1961

Released May 1961

Released April 1961

No release

79

75

78

88

71

61

62

71

2 5

5

3

3

15

16

7

4

2

^ From Hatchell (35). Release was obtained by injecting hardwoods with chemicals.

" No third-year data—study terminated.

Prescribed Fires

Prescribed—i.e., controlled—burns may be

made on almost any site except in the mountains, where they are difficult to control and

may induce erosion. Low coastal areas with

deep organic soils may be so wet that fires are

impossible during most of the year. They are

normally burned just ahead of sowing—that is,

in fall and winter for spring seeding. For early

fall sowing of longleaf pine on grassy sites,

burning should be done one growing season in

advance. The light grass rough that then develops provides a better germination environment for longleaf than does a newly burned site

While exposure of mineral soil is the main

effect of a presowing burn, there are additional

benefits. For longleaf seeding, fire removes

brown-spot infected foliage from natural seedlings. On sites with a heavy grass rough it

destroys the habitat of troublesome rodents

such as the cotton rat. Contrary to popular belief, burning does not have much effect on most

other common species of small mammals. Most

trapping studies have shown only temporary

reductions in animal numbers following a burn,

22
PS-5ISSS8

Figure 19.—Early release from overtopping hardwoods is essential for rapid pine growth. One-year-old loblolly seedlings on the

right were released in June; smaller ones were not released.

23
and in some cases numbers have increased (10,

36,91).

A single burn will also reduce competition

somewhat, but will not give sufficient control of

shrubs, small hardwoods, and palmetto. Though

a well-timed fire normally kills the aerial portions, sprout regrowth is often rapid. Thus additional preparation may be needed.

Disking

Disking is a more intensive treatment that is

widely used on open, grassy sites or where

palmetto and gallberry are abundant. It exposes

mineral soil and reduces competition—the

amount depending on its timing and intensity.

A single pass with a heavy-duty agricultural

disk harrow is sufficient on most grassy sites.

When confined to strips—separated by 6- or

7-foot undisked balks—this treatment has been

accomplished for about $2.50 per gross acre.

Disking for control of grass, palmetto, or

gallberry is most effective if done during the

summer or early fall. Hot weather and low soil

moisture increase the kill, and there is ample

time for the loosened soil to settle, thus reducing the proportion of seed lost by silting. Burning ahead of disking increases effectiveness of

the cutting blades.

Several studies with longleaf, slash, and loblolly pine have shown that disking markedly

benefits first-year survival in dry years (table

2). In two studies the subsequent seedling

growth was also improved (fig. 20a and 20b).

Heavy disks have proved useful in hardwood

stands in the northern part of the southern pine

range. The disks, which weigh several tons and

require large tractors, uproot small hardwoods

and at the same time expose a seedbed by turning under the heavy layers of leaves and duff

that are typical of such sites (fig. 21). The

disks are also effective on heavy soils that cannot be worked with ordinary machinery.

FS-5IS9S9

Figure 20a.—These slash pines were seeded on disi<ed beds. Af 6 years of age they averaged 3 feet taller than those shown on the

opposite page (fig. 20b), which were established in a grass rough on the same area.

24
Table 2.—Average survival and height of seeded pines

on disked and untreated seedbeds on open grassy

sites; data are from four studies

Species and First-year

survival ^

Height of dominants

seedbed At 5 yrs. At 9 yrs.

Pet. Ft. Ft.

Slash pine

Disked 28 8.2

Untreated 10 6.4

Loblolly pine

Disked 58 19.2

Untreated 37 16.2

Longleaf pine

Disked 65

Untreated 10

Slash pine

Disked 22

Untreated <1 —

' The first summer was dry during all trials.

Disking elevated seedbeds is a common practice on sandy flatwoods sites where water tables

are high (fig. 22). Competition from wiregrass,

titi, gallberry, and palmetto is greatly reduced,

and the soil is mounded for good seed germination and seedling growth. This treatment requires a special implement that throws the soil

inward from both sides, in contrast to the flat,

offset disks used in most situations.

While disking often improves survival and

early growth, initial seedling catch usually is

somewhat less than on comparable undisked,

burned beds, because some seeds are silted over

deeply by loose soil. Such losses can be partially avoided by letting disked soil settle before

pine is sown, but usually they must be compensated for by a higher sowing rate. Simple broadcast sowing is effective on disked ground,

though greater yields can be achieved with

machines that drop seeds in rows and have

packing wheels that put them into firm contact

with the soil.

Figure 20b.

26
fE

X- ^:f;-^''t-^^.

Figure 21.—A 3y2-ton disk destroys small, dense hardwood In preparation for direct seeding in Tennessee. (Photo by Tennessee River

Pulp and Paper Company.)

Furrowing

Another intensive seedbed treatment is furrowing with middlebreaker plows. It is costlier

than disking because the production is considerably less for the same expenditure of power.

On many soils, deep furrows create drainage

problems as well as a surface roughness that

hampers vehicle travel for fire control or other

purposes. Consequently, furrowing as a separate operation is usually limited to small ai»eas

or to well-drained sands. Furrowing plows,

however, are an integral part of many rowseeding machines that have been developed for

preparing seedbeds and sowing in one operation.

The principal advantage of furrows is the

complete removal of nearby competing vegetation. If sites are droughty, furrows usually are

superior to any other method of seedbed treatment. They are particularly advantageous on

some deep sandy soils. The firm soil at the bottom of the furrow has more moisture than untreated or disked surface soil and is ideal for

operation of equipment that sows seed at precise depths. Occasionally, furrow-making equipment is used to elevate a seedbed; seeds are

then placed on the common ridge between two

adjacent furrows.

On heavy soils, siltation or standing water

may cause substantial loss of seed in furrows.

Applicability of row seeders on such soils is

26
limited, because there is no time lapse for

initial melt-down of the loose soil. The problem has been alleviated somewhat by attachments that elevate a small ridge within the

furrow, but such ridges do not protect the seed

if furrows impede natural drainage or if erosion occurs on slopes not properly contoured.

On deep infertile sands, such as occur in western Florida, furrowing may reduce seedling

growth by displacing essential topsoil (89). In

more northerly areas, deep furrows may expose

heavy subsoil on which seedlings are subject to

frost heaving. Furrows, therefore, should be

cut no deeper than necessary to remove competing vegetation.

Site Clearing

Where disking or furrowing are inadequate

or impossible to apply, much more expensive

treatments are used. These are essentially landclearing operations and include removal of

vegetation by bulldozing, chaining, shearing,

or cutting with heavy drum choppers (fig. 23).

Except where erosion is a hazard, a burn is

generally made to reduce the debris (after it

has dried) and kill sprouts. Usually these treatments create a mineral seedbed, but occasionally the cleared site is also worked with a heavy

disk. Chaining and bulldozing are most effective on sandy soils, where large hardwoods are

easy to uproot. Shearing and chopping are in

greater use on all types of soils and sites. All

these methods give adequate control of hardwoods up to 12 inches in diameter, and there

is little apparent advantage between them.

Shearing is cheaper in some situations that

would require a double pass with a chopper.

Heavy-duty machines can be recommended

only for large-scale operations, after thorough

study of alternatives. They are most applicable

when a massive treatment is required to reclaim

sites from invading hardwoods and a large

volume of material must be removed or reduced.

They provide excellent conditions for direct

seeding, and have been used to convert many

thousands of acres to pine.

FS-SIS9gl

Figure 22.—Disking elevated beds improves tree growth on flatwoods sites with high water tables.

27
Site Amelioration

Direct seeding has been extended to sites that

require modification for optimum growth of

pine. Site modification, sometimes referred to

as site amelioration, includes drainage, high

bedding, and creation of artificial tussocks. Two

or more of these treatments may be applied to

the same site. They are often necessary in low

coastal areas and other places where drainage

is slow and water tables are high during much

of the year (-^2). Pines have shown a striking

growth response after sites were drained by

canals (61). Drainage has proved beneficial on

both sandy and deep organic soils.

High bedding (fig. 24) is an intensive disking or furrowing treatment done with equipment that elevates the seedbed about 5 inches.

In a modification of the treatment, small

mounds are created at regular intervals by

pushing up topsoil with a bulldozer blade. Seedlings established on the elevated beds have

grown faster than those on untreated sites. In

some wet areas, mounds or tussocks are the

only places where pine seedlings will survive

and grow (17).

FS-518992

Figure 23.—A heavy drum chopper preparing a site in north Georgia.

28
V i^'-^-<i.

k»M

áü^".

Figure 24.—Where surface flooding occurs, elevated beds can be made with furrowing plows.

~^» ¿-t. «i - «' ?¿

FS-SISeS3

DIRECT-SEEDING TECHNIQUES

This section is for the guidance of those responsible for the sowing phase of the directseeding job—the men on the ground. It summarizes research and operational experiences in

procuring, testing, and treating seed ; in selecting the optimum date and rate of sowing ; and

in distributing seed accurately by various

methods.

Seed Procurement

Only good seed should be used. If stocks do

not meet reasonable standards of quality, seeding should be deferred. Frequently, sowing is

done with seed that becomes available at the

last minute, or with "bargain" lots of dubious

quality—often on sites not properly prepared.

29
Some of these attempts succeed, but most fail,

and often it is the seeding technique itself that

is ultimately blamed for the failure.

Experience has shown that 85 percent viability is a realistic minimum when procuring

seed. Properly handled, most lots meet this

standard; mishandling or improper storage

should be suspected for lots that do not. If seed

viability falls much below 85 percent—to 60

percent, perhaps—vigor may be declining fast

and field sowing may be futile except under

ideal conditions. Frequently, sowing rates are

raised to compensate for low seed viability. This

procedure may be used for lots having 70 to 85

percent viability, but lots below this range

should be diverted to nursery sowing, where

germination conditions are under some control.

Purity or cleanness of the seed is also of concern. Foreign material or a large proportion of

empty seed reduces accuracy of all metering

equipment, and, of course, lowers the number of

sound seeds per pound. Modern seed-cleaning

machines are capable of removing most impurities. A reasonable specification for commercial seed is less than 2 percent impurities by

weight. A minimum of 95 percent sound seed

should also be specified, along with a moisture

content of 10 percent or less.

Commercial dealers have furnished the bulk

of the seed sown to date. Most of them have

modern facilities for handling large quantities

of cones, for dewinging and cleaning seed, and

for storing it. Consequently, they have been

able to supply seed in large quantities and at

reasonable cost. The main disadvantages of depending on commercial sources are the uncertainties of supply in poor seed years, nonavailability of local seed, and the possibility that

seed was collected from trees of poor form and

vigor.

While dealers may not always have "local"

seed, they can generally identify the geographic

source for lots available. Seed should be tested

for purity, germination, and moisture content

before it is purchased, and price should be

based on dry seed (10 percent moisture content

or less) without a coating. Costs of stratification and repellent treatment, if furnished by

the vendor, should be negotiated separately.

Both treatments add considerable weight to a

lot of seed.

Some landowners have economized by collecting their own cones. Such collections are especially effective when supplies for several years

can be obtained from a bumper crop. In addition, local seed is assured. On the other hand,

large-scale collections require an organization

trained to obtain needed quantities in a few

weeks. Equipment for drying cones and processing seed must also be available, unless this work

is contracted to a commercial firm.

A landowner should try to collect cones from

the best stands. When such stands are not producing cones or cannot be cut to facilitate seed

harvest, the only possible control of quality is

to avoid trees that are obviously defective or of

poor form (fig. 25). Open-grown trees often

bear the most cones and are a good source for

species that can be gathered by climbing—

longleaf, slash, and in some cases loblolly pine.

The quality of individual open-grown trees is

hard to judge, because all tend to have large

crowns and coarse branching, but if the defects

illustrated in figure 25 are absent such trees

may be considered acceptable. Most collections

from loblolly, and practically all those from

shortleaf, Virginia, and white pine, are made

from felled trees. Coordination of cutting operations is necessary, so that the cone-bearing

trees are felled after the seeds are ripe but before cones begin to open. With longleaf and

slash pines, mechanical tree shakers, of the

kind used in pecan orchards, are an alternative

to climbing or felling.

Cone and seed yields can be estimated in advance. There is, for example, a consistent relationship between the total yield of cones from a

tree and the number visible from a single position on the ground. On loblolly and slash pines

a careful man with binoculars can count onehalf of the total cones from a single observation

point {100, 102, 105). Several investigators

have developed formulas for estimating the

number of full seeds per cone from the number

of sound seeds exposed when sample cones are

bisected longitudinally with a sharp knife (fig.

26). Table 3 illustrates relations between count

of exposed seeds and seed yields from cones of

the major species. Since yields per bushel of

cones vary widely, these techniques are useful

in locating collection areas well in advance of

cone maturity.

Cones should be allowed to mature on the

30
-üíR:

FS-5I89B4

Figure 25.—Forking, low branch angle, and disease ore obvious defects to avoid in selecting trees for cone collection.

Table 3.—Seed yields per cone, as estimated from

number of seeds exposed when cones are

bisected longitudinally

Average

number

of sound

seeds

exposed

Total sound seeds per cone for—

Longleaf.'i

Louisiana

LobloUy.i

Louisiana

Slash.i

Louisiana

Slash,=

Ga.-Fla.

Shortleaf,=

Virginia

No. No. No. No. No.

2 23 31 20 31 12

4 35 44 35 50 22

6 47 57 50 69 31

8 59 70 65 87 41

10 71 83 80 106 51

12 83 96 95 124 60

14 95 109 110 143 70

' Prom McLemore (55).

"Prom Asher U).

^ Prom Bramlett and Hutchinson (11).

tree. Premature collection is a common error;

it reduces seed yield per bushel and probably

also depresses seed vitality for all species except perhaps Virginia pine (51, 101). Cones

may be considered mature when their specific

gravity drops to 0.89 or less. As dates of maturity vary from tree to tree, a fairly large sample is needed to estimate this stage for a stand.

Wakeley's method of estimation—when sound,

fresh cones from 19 out of 20 trees float in

SAE 20 motor oil—has stood the test of time

and is the easiest to apply (101).

Cones are often stored for varying periods—

either through necessity or to allow some predrying before kilning. The length and condition

of storage should be controlled. Bagged cones

stacked loosely on racks in a well-ventilated

31
FS-BIS99B

Figure 26.—A iongleaf cone sliced longitudinally to expose sound seeds, which are counted to predict seed yields.

building or an open shed can usually be held

for 30 days without loss of seed yield or vigor

(15). Longer storage may affect quality of the

seed (52), and any condition that allows molding of the cones is detrimental.

Gas-fired kilns, developed in recent years, are

capable of drying large quantities of cones

quickly. The final drying needed to open a cone

is often accomplished in less than 48 hours.

Small kilns, suitable for research and for the

landowner with 1,000 bushels or less to process

annually, have been developed (53). Local extraction also requires a tumbler for removing

seed from opened cones, a dewinger, and a small

fanning mill for cleaning the seed. Tumblers

and dewingers must be built locally. If im32
properly designed or operated, dewingers will

damage seed. Inspection of models in operation

is recommended before one is constructed.

Seed Storage and Testing

At one time, fresh seed was considered essential for direct seeding, but it is now known that

seeds of all species can be used after storage

for 10 years or more. Some species retain their

viability better than others, but all have essentially the same requirements for storage. These

are prompt drying after extraction to a moisture content of 6 to 10 percent (based on dryseed weight), followed by storage in sealed

containers at a temperature between 0 and

32° F. {Uy 46), Seeds of longleaf are the most

difficult to store ; they deteriorate faster and are

more sensitive to improper storage. High viability can be maintained for long periods (5^),

however, and good stands of longleaf have been

established with stored seed (6).

Proper storage in the few days or weeks during or immediately before seeding is important,

though frequently neglected. The safest procedure is to place seed immediately after receipt

under refrigeration at 34 to 36° F. However,

most lots, including stratified ones, can tolerate

a few days or even a week in a cool, dry, wellventilated warehouse. Common errors include

storage on damp ñoors, in warehouses where

temperatures exceed 80° F., and in compact

piles. Individual bags should have free ventilation to permit some drying and to prevent heat

buildup. For stratified seed, it is advisable to

repackage into sublots of 50 pounds or less if

short-term storage is necessary and coldstorage facilities are not available. Lots should

be examined frequently for evidence of heating

or molding, which can destroy viability in a

short time. If trouble is detected in time, the

solution is to spread the seed in thin layers for

aeration and drying, then repackage in smaller

containers.

Routine storage of repellent-coated seed is

not recommended, but occasionally seeding is

delayed by adverse weather or other factors

after the seed has been stratified and coated.

Several tests of repellent-coated, stratified seed

of loblolly, shortleaf, and slash pine have shown

that cold storage for 40 to 120 days is not

detrimental (Í5, 74, 76) ; storage for 1 year is

also possible {56), Slash pine, however, should

be dried to 10 percent moisture content before

storage. Restratification after storage is not

necessary for seed of any species. If storage of

loblolly and shortleaf pine becomes necessary

after stratification is completed but before the

repellent is applied, the seed should also be

dried before storage. Repellent-coated longleaf

seed, which is never stratified, can be stored for

a year if the moisture content is reduced to 10

percent or less (7). The recommended posttreatment storage temperature for all species

is 25° F. Chemical analyses of the repellent

coating have shown no loss of effective material

during 1 year of storage {56),

Hazards of the repellent coating should be

kept in mind in selecting storage space. Thiram

is not ordinarily considered dangerous, but the

endrin component is highly toxic. Treated seed

must be stored where it is inaccessible to livestock, pets, or children. It should not be placed

in cold lockers with unsealed food items.

Before use, seed lots should be carefully

tested to determine if (1) viability meets minimum standards, (2) sowing rates must be adjusted, and (3) stratification is needed for

spring sowing. Therefore, the tests must include

representative samples of both stratified and

unstratified seed and must be timed so that

results are available when needed. For example,

loblolly seed that may need 30 days of stratification must be sampled at least 31/^ months

before the planned sowing date. Facilities of

specialized seed-testing laboratories should be

used. In sand-flat tests on an office windowledge, variations in temperature, moisture, and

light may invalidate results. The Forest Service's Eastern Tree Seed Laboratory (P. 0. Box

1077, Macon, Georgia 31202) and some State

seed laboratories perform all tests needed to

evaluate purity and viability, and their fees are

nominal. Such laboratory tests also provide a

firm basis for judging the value of seed offered

for sale. Seed destined for long-term storage

should be tested before storage begins, and at

yearly intervals thereafter.

Stratification of Seed

Cold stratification usually improves the speed

and completeness of germination if seed is dormant (table 4). Rapid germination is desirable

33
Table 4.—Field germination of cold-stratified and

unstratified loblolly pine seed in three studies

Year of study

and seed

treatment

Germination after—

17 days 27 days 37 days 60 days

Pet. Pet Pet, PcU

1952

Stratified 12 27 31 32

Unstratified 0 1 5 9

1952

Stratified 24 36 38 38

Unstratified 0 2 4 14

1953

Stratified 26 30 30 39

Unstratified 9 16 26 32

in spring sowing, because it reduces the time

seed is exposed to predators, assures maximum

germination while weather conditions are optimum, and gives seedlings time for development

before the onset of hot, dry weather. Early

germination of stratified seed often improves

total seedling yield. In one study in which loblolly pine was spring-sown on four seedbeds,

stratified seed germinated promptly, but untreated seed gave low initial stocking when

drought reduced surface moisture below levels

needed for germination (table 5). Stratification

Table 5.—Initial stocking from stratified and

unstratified loblolly pine seed sown at

the rate of 1 pound per acre

Seedbed condition

and seed treatment

Seedlings

per acre

Increase from

stratification

No. Pet.

Heavy grass

Stratified

Unstratified

518

111

367

Light grass

Stratified

Unstratified

3,666

3,000

22

Disked

Stratified

Unstratified

1,556

278

460

Burned and disked

Stratified

Unstratified

2,333

1,334

75

All seedbeds

Stratified

Unstratified

2,018

1,181

71

is unnecessary in fall seeding, since seeds overwintering on the ground are adequately conditioned.

Stratification usually improves total germination as well as speed of germination. Occasionally a slight reduction in total germination

occurs, but long periods of stratification are

usually no more harmful than short ones. Substantial reductions have been observed only in

lots of such low viability that they were unsuited for direct seeding. Apparently the weak

seeds are killed soon after stratification starts.

Longleaf seed, which germinates promptly,

never requires stratification, but the other

southern pines usually benefit {18, 30, 31, 58,

6Í, 65, 90). Optimum length of treatment varies

by species and lots. Fresh, well-handled seed is

usually less dormant than seed that has been

stored or mistreated. The only sure way to

determine stratification needs is to compare

laboratory germination of sublots stratified for

various periods.

How are test data interpreted when deciding

whether and how long to stratify? There are

no hard-and-fast rules. Properly conditioned

seed should reach peak germination in 7 to 10

days, and germination should be essentially

complete in 15 days. (Peak germination is the

highest value obtained by successively dividing

number of days of test into cumulative germination percent (57).) If stratification shortens

time to peak germination by 1 or 2 days in

laboratory trials, a greater improvement may

result in the field where germination is slower

and differences between lots are accentuated.

If tests to determine stratification needs are

infeasible, blanket recommendations are to

stratify loblolly pine seed for 60 days, shortleaf

for 45 to 60, and slash, Virginia, and white

pine for 30 days. In emergencies, shorter

periods—10 to 15 days—are better than no

treatment.

Stratification can be accomplished in several

ways. The main requirements are to keep the

seed moist and at a temperature between 34

and 36° F. Seed should not be allowed to freeze,

and when large lots are treated, frequent inspection and other precautions are needed to

prevent heating and molding.

Granulated peat moss may be used to maintain moist conditions ; a suggested procedure is :

34
1. Cut drainage holes in the bottom of a

metal container (a 55-gallon steel drum

will handle about 150 pounds of seed),

then support upright container on three

or four bricks to allow free drainage of

excess water.

2. Weigh out 25-pound sublots of seed, putting each sublot in a separate cloth bag.

Tie the bags loosely so that they can be

spread to a uniform thickness in the

drum. Dip each bag in water to wet seeds

thoroughly.

3. Pulverize granulated peat moss, soak it,

and squeeze out excess water. Place a 4-

inch layer in bottom of container and

tamp firmly.

4. Place a bag of seed on top of the moss and

spread it evenly so that the layer of seed

is not more than 2 inches thick.

5. Continue alternating layers of moss and

seed ; each layer of moss, including the top

one, should be at least 4 inches thick.

6. Refrigerate the filled containers at 34 to

36° F. Inspect drums weekly, and add

water at 2-week intervals to keep the moss

wet but not saturated.

In another method, used for small lots and

becoming popular for large ones, lightweight

polyethylene bags are substituted for the container and peat moss (25, iO, ^8, 68). Seeds are

soaked in water for about 12 hours, then placed

in the bags and refrigerated at 34 to 36° F. The

sealed, impervious bags hold in moisture. However, they must be inspected frequently and the

seed re-wetted if its surfaces become dry. The

amount of seed per bag should not exceed 25

pounds; larger quantities may heat or mold.

Bags should be stacked one layer deep, and

turned weekly.

The stratification methods described are not

new ; they have been used for many years. Seed

dormancy is the subject of much research, and

developments may be expected. Ways of shortening the period of treatment would be desirable, but to date no shortcut methods have

proved reliable. For example, soaking in hydrogen peroxide, citric acid, or water has some

stimulating effect but usually fails to give the

fast and complete germination that is desired

in direct seeding.

Seeds gain considerable weight during stratification. If the 25-pound sublots are kept intact,

the subsequent repellent treatment and field

sowing can be done easily on a dry-weight basis.

Coating Seed with Repellent

Only one repellent formulation is described

in this handbook; others that were recommended for southern pines in earlier reports

are either obsolete or no longer available

through commercial sources. The current formulation containing thiram and endrin gives

a high degree of protection against all important species of seed-eating birds, deters

small mammals, and destroys troublesome insects common to most southern pine sites {1,21 y

78, 85). Scores of field studies, tests with caged

animals, and operational seedings since 1956

have confirmed the repellent properties of these

chemicals. Typical results are given in table 6,

which compares initial stands from properly

coated seeds with those from untreated seeds.

The trials were on sites having normal populations of birds and rodents.

Table 6.—Seedling yields in field studies comparing

repellent-coated seed with untreated seed

Species

Seedlings per

acre from— Tree percent i

Year

Thiramendrin

repellent

untreated

control

Thiramendrin

repellent

Untreated

control

No. No. Pet, Pet.

1956 Longleaf 8,220 55 51 <1

1956 Slash 2,335 705 10 3

1957 Longleaf 8,720 0 75 0

1957 Slash 4,705 330 30 2

1958 Loblolly 10,185 1,590 54 8

1958 Longleaf 5,610 170 38 1

1959 Longleaf 8,670 0 67 0

1959 Longleaf 6,080 110 47 1

1962 Loblolly 5,670 640 28 3

1962 Slash 5,140 440 26 2

^ Percent of total seeds that produced a seedling.

Thiram is the bird-repellent component in the

formulation. It is a commonly used seed-treating fungicide that is available in many forms.

A water suspension of finely ground thiram,

equivalent to the proprietary material called

Arasan 42-8,^ is best for treating pine seed

^ Mention of trade names is solely for information.

No endorsement by the U.S. Department of Agriculture

is implied.

35
(22), It contains no harmful additives, creates

no dust problems, and forms a hard coating.

Wettable endrin is blended with the bird repellent for control of small mammals and insects. It is a toxic material that must be applied

at a carefully controlled, low dosage rate, and

always in combination with the bird-repellent

chemical. Studies in various parts of the South

have invariably shown that endrin is needed.

Rodents are nearly always present in sufficient

numbers to destroy or severely damage a seeding. Furthermore, endrin provides protection

against damage by insects of many species.

Proposed seeding projects should be reviewed

with State Fish and Wildlife and State Health

Departments to determine possible adverse effects on non-target animals. Some species of

birds and other wildlife feeding on treated

areas may not be repelled by the thiram, and

occasionally there may be ingestion of a lethal

amount of endrin.

Endrin is marketed in several forms, some of

which cannot be blended into the thiram suspension. The form most successful is a 50-percent

wettable powder, equivalent to the Stauffer

Chemical Company's Endrin 50-W Seed Protectant.

A latex sticker must be added to bond the

repellents to the seed. Though a number of such

adhesives are available, only one has been used

with the liquid suspension. It is Dow Chemical

Company's Latex 612 (formerly Latex 512-R),

which was selected initially because it is widely

available, has good adhesive properties, and

does not affect germination.

The final ingredient in the repellent formulation is aluminum powder applied as an overcoating to hasten drying and to lubricate the

treated seed. It is produced in many grades. A

100-mesh leafing powder has proved satisfactory. A proprietary product is Varnish Lustre

Powder M.D. 2100, manufactured by Metals

Disintegrating Company, Inc., Elizabeth, N. J.

The repellent formulation must be prepared

by the user. A mixture containing I/2 pound of

Endrin 50-W and 5 fluid ounces of undiluted

Latex 612 per gallon of Arasan 42-S has proved

satisfactory for treating all species. A simple

four-step procedure for preparing about 6 gallons follows, and smaller amounts can be mixed

in a similar manner :

1. Place 2V2 pounds of Endrin 50-W in a

coated-metal or glass container, add 2V2

gallons of Arasan 42-S, and stir slowly

with a paddle until the powder is wetted.

Caution: Endrin is highly toxic. Wear

rubber gloves while treating seed and use

a respirator during the mixing phase

when endrin dust is present. Clean or destroy empty containers so as not to endanger man or animals,

2. Beat to a smooth lump-free mixture with

a paint stirrer attached to an electric

drill having a no-load speed of at least

1,200 r.p.m.

3. Add 25 fluid ounces of undiluted latex to

another 2^4 gallons of Arasan 42-S and

stir briefly with paddle.

4. Blend the two mixtures by pouring from

one container to another about 10 times.

The final mixture is a heavy water suspension

of thiram and endrin solids that tends to thicken in storage but thins out quickly with a little

stirring. No additional water is required for

thinning. The formulation is stable and can be

prepared several days in advance. However, it

must be mixed and stored at above-freezing

temperatures and in the original coated-metal

cans or in glass containers.

Figure 27 illustrates the main steps in preparing the repellent and coating the seed. Small

concrete mixers are excellent for applying the

repellent. The model illustrated will handle 25

pounds of dry longleaf seed per batch and at

least 50 pounds of the small seeded species.

The amount of liquid repellent required for

an optimum seed coating varies by species and

moisture content of the seed. Small-seeded

species need less than the big, light seeds of

longleaf; stratified seeds take less than unstratified. Consequently, it is advisable to do

some testing initially. As a start, about 1 gallon

of the mixture can be applied to 50 pounds of

seed. The first batches should be examined carefully to determine if all seeds are fully coated

with no surplus. The dosage should be increased

or decreased until a complete, uniform coating

is obtained. If too much is applied, seeds will

stick together in large clumps.

A batch can be coated in about 3 minutes.

Once seeds are thoroughly coated, continued

tumbling does no further good and may be

harmful. The aluminum powder overcoating

36
Figure 27.—Directions for preparing repellent and applying if to seed.

FS-B18996

Add 21/2 pounds of Endrin 50-W to Th

gallons of Arasan 42-S.

FS-518997

Stir with wooden paddle.

FS-518998

Beat with paint stírrer.

Î

, -.

^^^Vij^^

FS-518999 FS-5I9000 F5-5I900I

Add 25 fluid ounces of undiluted Dow Latex 612 Blend by pouring from can to can about Pour finished repellent directly onto seed

to another 2V2 gallons of Arasan 42-S. 10 times. as mixer is turning. Tumble about 2 min.

FS-5I9002

Add aluminum powder and tumble for another minute.

FS-519003

Seed is fully coated; it should be spread out to dry.

37
should be applied as the last step—in the final

minute after seed and repellent have been

thoroughly mixed. It should be put on at the

rate of about 8 tablespoons per 50 pounds of

seed.

Small lots can be treated in an open container

by stirring seed and repellent with a ladle.

About 3 ounces of repellent will treat a pound

of seed. The aluminum is added last, just as

with large batches.

The coating should cure for several hours;

it is similar to latex paint, which dries rapidly

but requires setting time before it can withstand exposure. Freshly treated seed can be

spread out on a floor in a layer 3 to 4 inches

deep and stirred frequently with a rake during

initial drying—until the color of the coating

changes from gray to white. The raking reduces

clustering. Seed can also be dried in bags in

forced-draft kilns if kiln temperature is held

to 100° F. or less. However, this procedure

favors formation of clusters, which must be

broken apart before the seed can be sown.

The type and amount of adhesive represents

a compromise between durability and permeability. The coating must hold up in the field,

but it must also permit passage of moisture and

gases needed for normal germination. A coating

should remain effective for 3 or 4 months under

field conditions. With poor application, its lifespan will be shorter.

All coatings, whether applied on the job or by

a commercial dealer, should be checked for

durability. After the coating is thoroughly dry,

a simple test can be made by placing a representative sample of several hundred seeds in a

food strainer, holding them under a cold-water

faucet for 2 minutes, and then redrying. If

the coating remains on at least two-thirds of

each sample seed, the repellent will weather

satisfactorily (fig. 28). If the loss is greater,

or if 20 percent or more of the seeds lose their

coating entirely, application was unsatisfactory

and the seed should be thoroughly washed and

re-treated. Common causes of poor durability

are improper mixing of the repellents, inadeFS-&19004

Figure 28.—Rapid field lots of repellents from improperl/ treated seed (right) can be predicted by washing a sample in cold running

water. Properly treated seed (left) loses very little coating.

38
quate amount of sticker, or use of latex that

has deteriorated in storage or has been damaged by freezing (20),

When the repellent treatment is to be furnished by a vendor on a custom basis, coating

ingredients and treatment methods should be

specified exactly. It is not suflScient to specify

"repellent-treated seed," as this term properly

applies to seed treated with several materials

and to a wide range of dosages.

There has been a tendency to alter the treatment to save money, or from a belief that the

recommended maximum amounts are not required.

Labor cost is nominal; a three-man crew

using a small concrete mixer can easily treat a

ton of seed per day, and altering the treatment

seldom speeds the work much. Cost of materials

runs about 21 cents per pound of dry seed.

Skimping on chemicals therefore saves only

pennies per acre. For example, cutting the

amount of thiram from 8 to 2 percent saves

12 cents per pound of seed. While the lower rate

has been used with some success, it rarely is as

effective as the higher one. This was clearly

demonstrated in a series of trials in Virginia

where the 8-percent concentration consistently

outperformed a 2-percent concentration, sometimes with twice as many 1-year-old seedlings

from the same amount of seed (79).

The recommended dosage for endrin is 0,5

percent active ingredient^ by weight, A 50-percent reduction in this rate will save only 2,5

cents per poimd of seedy and the lower level will

not afford adequate protection,

Thiram is slightly phytotoxic to seeds of the

southern pines. Germination is often adversely

aifected in laboratory tests, where seeds are

concentrated in a small tray. But in numerous

field trials germination of thiram-coated seed

has equalled or exceeded that of untreated seed.

Seeds of some species may not tolerate thiram

as well as do the southern pines, and the dosages recommended here should not be applied

to other conifers without preliminary testing

under field conditions.

Time of Sowing

There are two distinct sowing seasons—

spring and fall—over most of the South. Fall

is generally recommended for longleaf pine.

Seeds of the other species—^loblolly, slash, shortleaf, white, and Virginia pine—have been sown

in both seasons, but spring generally gives the

best results. Germination characteristics of the

individual species were described earlier (p.

13) ; of concern here is selection of the best

date within each season.

The best time for fall sowing is the earliest

date after natural seedfall and after soil moisture has been recharged by 2 to 4 inches of rain.

With rainfall as a factor, the date may vary

considerably from year to year. The alternative

is to sow on a preselected date regardless of soil

moisture, but then the hazard is that initial

rains may be suflScient to start germination but

not adequate to sustain it.

If rains are delayed, longleaf can be sown

well into December, though temperatures for

germination usually are better in November.

Longleaf will, in fact, germinate throughout

the winter, but cold weather from midDecember through mid-February slows the

process and lowers seedling yield.

Slash pine can be sown for fall germination

if moisture supplies become adequate when

temperatures are still warm. The best months

are October and November. If conditions delay

sowing beyond December 1, the seed should be

held in storage until spring. Near the Gulf

Coast fall sowing is more reliable than elsewhere in the species' range. It is hazardous

where winter temperatures drop well below

freezing, because the young seedlings may be

killed by cold weather.

The spring season, for direct-seeding purposes, is defined as the transition period between winter dormancy and appearance of new

foliage—about the time first blooms appear on

redbud and red maple. It varies by latitude and

is generally about February 15 in the latitude

represented by a line from Shreveport, La.,

through Jackson, Miss., to Macon Ga. Normally,

prolonged periods of freezing weather are past,

soil moisture is adequate, and daily temperatures

are reaching levels needed for germination.

Stratified seeds of loblolly, slash, shortleaf, and

Virginia pine sown in mid-February usually

complete germination by mid-April, though

prolonged cool weather or drought can extend

germination into May.

Delays in spring sowing are likely to affect

results adversely (S7), If dates for seed de39
livery or performance of contractual services

are uncertain, it is best to schedule the work

earlier than the desired date. On the other

hand, danger of seed submergence may justify

postponement for as long as 60 days. Flatwoods

sites, for example, often have standing water

in early spring, and sowing must be deferred

until they dry. Similarly, the chance of flooding

in or adjacent to creek bottoms and other water

courses may dictate late sowing.

Table 7.—Average number of seeds per pound and

suggested sowing rates per acre

Sowing Rates

Sowing rates vary considerably, even within

species. They are influenced by quality of the

seed, method of sowing, and stocking desired

by the individual landowner.

As table 7 indicates, general recommendations for broadcast sowing are 3 pounds of seed

per acre for longleaf pine, 1 pound for slash

and loblolly, and 0.4 pound for shortleaf and

Virginia pine. These rates provide between

12,000 and 19,000 viable seeds per acre. They

have proved to be realistic ; under average conditions, initial stands have ranged between

2,000 and 5,000 seedlings per acre. For sowing

strips, rows, or spots the rate is much less.

The rates proposed in the table are for dry,

untreated seed with viability of 95 to 100 percent and for average numbers of seeds per

pound. Counts per pound vary considerably,

and precision can often be improved by determining the count for an individual lot and then

adjusting the sowing rate.

Strip seeding, as envisaged for the table,

means broadcasting seed only on disked strips

and not on the undisked balks between strips.

If the disked and undisked portions are of

equal width, the rates recommended for broadcast sowing can theoretically be halved. It has

been found in practice, however, that disked

ground requires a slightly higher sowing rate

to compensate for seed lost by silting. Hence,

0.6 as much seed as required for complete broadcasting is a realistic quantity per acre for strip

seedings in which one-half of the total area is

prepared. Other ratios of prepared to unprepared ground are handled similarly, except that

where the strips are very narrow the operation

becomes a form of row seeding.

Species

Seeds

per

pound 1

Weight of dry seed per acre

for seedingBroadcast

Disked

strips 2

Rows 3 Spots ^

Longleaf pine

Slash pine

Loblolly pine

Shortleaf pine

White pine

Virginia pine

No.

4,500

13,000

18,500

45,000

22,000

45,000

Uhs.

3.00

1.00

1.00

.40

1.00

.40

JJDS.

1.80

.60

.60

.24

.60

.24

1.60

.55

.39

.16

.33

.16

U)s.

1.33

.46

.32

.13

.27

.13

^ Dry, untreated seed, with viability of 95 to 100 percenty

^ Seeding restricted to disked ground, which is assumed to be 50 percent of the total ground surface.

^ Six feet between rows.

* One thousand spots per acre.

In row seeding, the sowing rate is controlled

by the number of seeds per chain (66 feet) and

the distance between rows. That is, number of

seeds per acre equals —^ X S, where x is the

average distance between rows in feet, and S

is number of seeds per chain of row. Experience

has shown that placement about 1 foot apart

is usually adequate. For rows spaced 6 feet

apart, as assumed in table 7, this provides more

than 7,200 seeds per acre.

In spot seeding, the objective is one established seedling per spot. Extra trees are superfluous, though clustering of several per spot

does not affect growth of the most vigorous one

{13, 81), To achieve this objective consistently

requires sowing about six seeds per spot {69),

If site conditions permit, about 1,000 spots per

acre are desirable. In terms of seed requirements, spotting is roughly equivalent to row

seeding.

The weight of seed per acre must be increased when a lot contains material amounts

of nonviable seed. If a lot of shortleaf pine seed

tests 80 percent viable, for example, a pound

containing 45,000 seeds would have only 36,000

viable seeds. The weight of seed required to

give 45,000 viable seeds per acre would be 125

percent of the recommended weight (45,000/

36,000 X 100), or an increase of 25 percent.

Control of sowing rates in the field is normally based on weight of dry untreated seed,

because treated seed, especially if stratified,

changes weight constantly. Such control is

40
facilitated if dry-weight records are retained

for each bag of seed. When this information is

not available the treated weight must be used

to control the rate of sowing. In these situations, a current estimate of the number of

treated seeds per pound is helpful in determining the weight required per acre.

The rates suggested here are for average sites

and normal weather. They can be reduced

locally after enough experience is acquired for

prediction of yield. A prerequisite for such

"prescription sowing" is an experience record

of sowing rate and subsequent first-year survival by soil types and cover conditions (9, 79).

Conversely, higher rates are sometimes desirable on adverse sites or where there has been

a substantial investment in site preparation. If

a higher rate will insure success, the cost of

extra seed usually is less than the cost of retreating an inadequate stand.

Distributing Seed-Ground

Methods

Hand sowing is the oldest form of direct

seeding. By this method, hundreds of research

plots were seeded as well as many of the early

practical trials. The term, as used here, includes

broadcasting, sowing with hand-operated cyclone seeders, and spot seeding with or without

special scalping and seed-dispensing tools. In

this age of mechanization, hand seeding is

limited to small areas and to those where soil or

cover conditions prevent operation of larger

equipment.

Simple broadcasting by hand i mentioned

only because it is a way of scattering seed over

disked strips when the intervening undisked

ground is to remain unseeded. It is not very

accurate ; with small-seeded species an extender,

such as sawdust, is needed to keep sowing rates

within rough limits.

For broadcasting on areas up to several

hundred acres in size, hand-cranked seeders are

very efficient (fig. 29). They have a simple

metering device which, if properly adjusted,

will regulate seedflow to within 10 percent of

the desired rate. Their effective swath is about

16 feet; thus, to sow an acre requires V2 mile

of walking. Where movement and swath control

are easy, a daily production of 15 acres per man

is common. On rough terrain or in heavy brush,

the rate averages about 10 to 12 acres per manday. Crew organization is simple and flexible;

men can be used singly or as a team with up to

six walking abreast. Larger crews are difficult

to control accurately. Operators need training

to walk in proper alignment and to maintain

a uniform rate of seedflow through the machines.

FS-G1'J00S

Figure 29.—Hand-operated grain seeders can be used for tracts up to several hundred acres in size.

41
Vehicle-mounted broadcast seeders designed

for seeding pastures and forage crops can be

adapted for pine. Their use has been limited,

because the large open areas where they are

most effective also are good opportunities for

aerial seeding. A common type mounts on the

front or rear of a tractor and has a centrifugal

slinger similar to that of a hand-cranked seeder.

Preferably the slinger is driven with an electric

motor. Connection to the power takeoff is less

desirable, because a constant engine-to-ground

speed is difficult to maintain on rough sites.

These machines will seed a 1/2-chain swath (33

feet), and on favorable terrain can cover 10 to

15 acres per hour.

Spot seeding is a good alternative where vehicles cannot operate and especially good where

other seedbed treatments, including fire, are

impractical. A spot is raked, hoed, or kicked

free of vegetation and litter, and six seeds are

dropped and pressed into mineral soil with the

foot (fig. 30). Several hand tools have been

developed to ease the task {12, 66). Most combine a scarifying blade with a metered container that releases the proper number of seeds

onto the spot when a lever is pulled.

Spot seeding is better adapted to areas with a

ground cover of hardwood litter than to sites

with grass sod. Prepared spots should be at

least 1 foot in diameter—larger where hardwood litter is deep—and the cleared-off debris

should be scattered to prevent blowback. Burn-

.' ■■ .n; - "• '^ "- »''W ' '.««,. **'ifc. TKS^

55? A--

FS-SI9O06

Figure 30.—Spot sowing, in which six seeds are ploced on hoed or releed spots and pressed into firm contact with mineral soil, is a

good method for small tracts and rough terrain, or where other seedbed treatments cannot be used.

42
ing before spotting eliminates blowback and

makes the work easier.

At the recommended minimum rate of 1,000

spots per acre, 2 to 4 acres can be covered per

man-day.

Mound or tussock seeding, a variation of

spotting, is useful in the swampy or flooded

portions of the Lower Coastal Plain. Seeds are

dropped by hand on clumps of grass or rotten

logs, at the base of stumps, and on any other

suitable spots above water level.

Some exposure to the repellent chemicals is

inevitable with all methods of hand seeding.

Precautions should include use of rubber gloves

for direct handling of treated seed, thorough

washing of hands before eating or smoking,

and a daily change of clothing.

While the methods just described are useful

in many situations, most seeding from the

ground has been done with row-seeding machines. Many types of row seeders have been

developed. Some simply drop seed in rows on

previously prepared ground, but most plow a

furrow or pulverize a narrow strip with disk

blades and then meter out seeds and press them

into the mineral soil with packing wheels. Hence

the term "row seeder" usually denotes a machine that prepares beds and sows in a single

operation. Width and proñle of the treated

strip vary considerably.

The first successful machine of this type (fig.

31), still in use, combines a conventional fireplow, a mounding or hilling device, and an

agricultural seed dispenser (19), It has proved

effective in fairly heavy brush and on a variety

of soils, except poorly drained ones. Heavy

power requirements and high maintenance on

the plow limit its usefulness. A production rate

of 15 acres per day has been reported, but it is

doubtful if this rate could be sustained for long

periods.

A row seeder that has been widely used in

sustained operations is illustrated in figure 32.

The front-mounted V-blade cuts a broad, shallow furrow and makes a shallow groove in the

center of it. Seeds are dropped into the groove,

and a dragplate at the rear of the tractor covers

them lightly with soil. This machine is designed

for light sandy soils; it operates effectively

where hardwoods are small enough to be uprooted with the V-blade.

Several compact row seeders have been developed. They are designed for fast operation

with minimum power requirements. Consequently, they cut a narrow, shallow furrow for

placement of the seed. They operate best on

sandy soils and can maneuver around large

hardwoods. All current models have a device

for covering the seed. Several deposit the seed

in a shallow trench that is opened by an agricultural sword and closed by a packing wheel.

On one, a small set of rolling blades cuts shallow slots into which the seed is dropped; the

slots are partially closed by a packing wheel but

full coverage is dependent upon movement of

soil by rainwater. None of these seeders assure

coverage to a uniform depth, but they are superior to machines that simply drop seed on

loosened soil.

In row seeders of still another type, disks are

used to prepare the bed. One model, used extensively on open, grassy sites, has two 2-foot sections of an agricultural disk arranged in tandem

to create a flat bed just ahead of the seeder

(fig. 33). This machine requires less power

than a plow—two units can be pulled by a light

crawler tractor—and it can function on poorly

drained soils where furrows might accumulate

water. The dual unit can cover 30 acres per day.

Another disk seeder has been developed

specifically for low, poorly drained sites that

are cleared and disked initially in the summer

before seeding. Its disk blades elevate a narrow

bed, 3 to 4 inches high, which prevents seed

submergence and improves initial growth on

sites where water tables are high. The same

principle is employed in a larger unit designed

for grass-covered flatwoods sites. The elevated

bed it creates is about 6 inches high and 6 feet

wide.

Disk seeders have two main drawbacks. First,

they leave rough beds on which considerable

seed is lost by silting. Second, disking in cool,

wet weather fails to control grass adequately.

Disk and furrow seeders alike are equipped

with modified agricultural seed-dispensing devices that work satisfactorily under optimum

conditions but are inaccurate on rough ground

or where there are numerous roots in the plow

zone. A recently developed device that is accurate under normal forest conditions employs a

vacuum system to move seeds from a hopper

and drop them at precise intervals (83), Plans

and specifications are available from the San

43
B

.«.• ^

.t»..'ii-3?ii^^i

FS-519007

Figure 31.—This row seeder elevates a low ridge in the center of a plowed furrow and drops seed onto it at regular intervals.

Dimas Equipment Development Center, USDA

Forest Service, 444 E. Bonita Avenue, San

Dimas, Calif. 91773.

Aerial Seeding

An estimated 75 percent of the total acreage

seeded has been sown from the air, either with

small fixed-wing craft or helicopters. On operations exceeding 500 acres, aerial seeding is comparable in cost to most ground methods of

broadcasting seed. It is also fast, permitting

completion of work while conditions are suitable for germination. Frequently, it is the only

practical means of sowing inaccessible terrain

or debris-covered areas. Properly calibrated

and controlled, aerial seeding is the most accurate broadcasting method, giving complete cov44
FS-SI9008

Figure 32.—A front-end row seeder designed for sandy sites and capable of operating in brush.

erage regardless of terrain, brush, or debris.

Pine seeding offers off-season employment

for pilots whose main income is from agricultural work or maintenance of utility rights-ofway. The flying techniques are essentially the

same, but seeding requires a very low application rate per acre, and terrain or tree cover

usually makes control of flight lines difficult.

In seed distribution there is not much difference between planes and helicopters. Powerdriven seed meters and a centrifugal slinger

must be used on a helicopter (fig. 34), while

planes can operate with gravity flow of seed

into a venturi-type distributor (fig. 35). The

power-driven equipment can be calibrated more

accurately and gives good distribution across

the flight strip, but the simpler equipment on

fixed-wing craft is adequate when properly

m
Ijj^ljj^têÊÊMMÊmJÊfÊStr y' '

'fl^W

&«JBIr • •'-•'* •' '^ ' •'

*^

Figure 33.—Disks on this seeder prepare a fiai bed.

FS-5I9009

used. Both types require constant checking and

precision flying for best results.

The main distinction between the two types

of aircraft is in width of the night strip. Helicopters will seed a strip 1.5 chains wide (99

feet), while planes should be limited to 1 chain.

Both types will distribute seed farther than

these distances, but some overlapping of strips

is needed to insure uniform coverage.

Helicopter charges are more per acre but the

sowing rate is about 300 acres per hour, as

compared to 180 for a plane. The difference is

mostly in time required for loading ; helicopters

can land on or near the site, while planes

usually operate from a landing strip several

miles away. Since faster operations lessen overhead costs and outlays for ground crews, total

expense is about the same for both types of

craft.

The following discussion is written in terms

of the helicopter, whose use in agriculture is

increasing rapidly. With minor modifications,

however, the information is applicable to airplanes.

Aerial seeding has evolved as a cooperative

venture between the contractor and his customer. Usually the flying service charges a peracre fee and furnishes the aircraft, pilot, and

one or two additional men to assist in loading

seed and calibrating equipment. The landowner

supplies the seed, overall supervision, and personnel for ground control. He also does any

mapping required for control of flight lines.

The role of each party should, of course, be

agreed on in advance.

Accurate aerial seeding requires good ground

control, which is often diflicult on rolling terrain or where there is a high canopy of hardwoods. Preparation for it is needed in most

cases; requisites include a large-scale map of

the area to be seeded, location of the flagmen's

positions for each flight line, and marking tract

boundaries with a plowline where they are not

distinct from the air. In addition, most flying

services insist on a preliminary reconnaissance

flight to check location and boundaries. A helpful technique is to delineate each flight strip on

the map (fig. 36). Flight strips should be numbered on the map and in the field to facilitate

systematic positioning of flagmen where the

46
Figure 34.—The power-driven slinger on a helicopter distributes seed over a 99-foot swath.

FS-BI90I0

Figure 35.—Up to 1,500 acres per day can be sown from a light airplane. Seed flows by gravity into a distributor that spreads a 66-

foot swath.

47
149.6

SEC. 25 T. I N. R. 14 E. SCALE 1,000'

Figure 36.—A large-scale map, showing tract boundaries and estimated acreages in each flight strip, is essential for accuracy.

pilot will be able to see them. Numbering is

particularly helpful when mechanical trouble

or adverse weather interrupts seeding. The

acreage and seed requirements for each mapped

strip can also be calculated in advance, thus improving control of seeding rate.

On most tracts, at least three flagmen are

needed—one on each flight strip terminal and

a third in the center. More may be required on

long strips, on rolling terrain, or where large

trees restrict the view from the aircraft's operating altitude of about 150 feet. After finishing a strip and turning, the pilot needs at least

two flags in view to align a new strip ; the nearest flagman ordinarily cannot be used, since he

will either be moving to the new strip or not

easily seen from the turning craft (fig. 37).

Correct alignment of flags is essential for accuracy and usually is not difficult when positions

are located by measurement in advance. If flagmen are expected to estimate strip widths by

pacing, huge errors in flight alignment may

result.

Adequate coverage of the area and control of

the sowing rate are responsibilities of the pilot.

He calibrates the metering equipment, determines flying altitude and speed, and instructs

flagmen on procedures for correct alignment of

flight lines. For pilots experienced in aerial

seeding, calibration is a routine procedure

normally done in cooperation with the project

supervisor just before seeding starts. For

others, a detailed description of this important

step is given in the next section.

Windspeed and wind direction must be considered carefully. Both can distort the seedfall

pattern beyond the capability of the pilot to

control it. Calm air is best, though rare during

the seeding seasons. On most jobs, therefore,

some work must be done in the wind. Steady

winds up to 10 or 12 m.p.h. do not seriously

affect the seedfall pattern, but if winds are

stronger, or if they are gusty, seed distribution

becomes erratic. Since some pilots are inclined

to continue work in high winds, the landowner

should retain the option of suspending operations whenever good seed distribution cannot be

attained.

48
f^-â*

:i.*ew,i«»., r,_

^¿ 0 U*f^"'

^'

rV'

1, ',•„ .,,»•

^..jaHHHHWBBHWi

PS-SI9012

Figure 37.—Flagmen must be placed so that the pilot can align his course on two flags at the start of each flight line.

When there is a choice, flying crosswind is

preferable to flying parallel, as it permits more

accurate control of groundspeed in both directions. A crosswind blows seed downwind and

has a tendency to windrow it, i.e., to cause

bands of alternating high and low densities, as

windspeeds increase. Flying can be done with

a paralleling wind if it is steady and the pilot

feels he can adjust his airspeed to maintain a

constant groundspeed in both directions. On

operations where ground-control points are

established in advance, planned flight lines

should be at right angles to the direction of the

prevailing wind. The lines usually are not

changed for a paralleling wind unless terrain

requires it or the pilot insists.

With experienced and responsible contractors,

strict performance standards are seldom required. However, there are opportunities in

aerial seeding for the irresponsible contractor,

simply because the timberland owner, unlike

the farmer, cannot see results of the work for

several years. Performance standards should

specify the allowable error in rate of sowing,

time limits set for doing the work, and the percent of random milacre (1/1,000 acre) plots

acceptable without seed. It is not realistic to

specify a minimum average number of seeds

per plot, for this implies that observers can

find all seeds that fall on a sampled plot.

Calibrating Seeding

Equipment

Proper calibration—adjustment of the seed

release mechanism to the desired sowing rate—

is important in all operations; precision calibration is essential in some. For example, a

49
helicopter flying at the usual speed of 60 m.p.h.

can release up to 36 pounds of seed per minute.

A row seeder, at the other extreme, may not

use this amount in 2 days. For best results, the

rate of seedflow should be rechecked frequently

during the seeding operation and readjusted as

necessary. Repellent-treated seeds of the six

pines vary considerably in flow characteristics ;

none are outstanding, and satisfactory flow of

partially dewinged longleaf seed is difficult to

obtain with any equipment.

Seeds of all species should be screened to remove clusters and foreign objects, which can

cause much delay and inaccuracy, especially in

aerial work. A simple wooden frame supporting

14-inch-mesh hardware cloth is adequate for all

species except longleaf, which requires 1/2-îïich

mesh.

The weight of treated seed required per acre

must be determined before calibration. It can be

obtained in two ways: (1) weigh several representative bags of treated seed for which the untreated weight is known. Calculate the difference

in percent and apply this correction factor to

the weight of untreated seed desired per acre,

or (2) divide the total weight of treated seed

allocated to an area by the area's net acreage.

Since treated seed fluctuates in weight, especially when stratified, the amount required per

acre should be determined just before seeding

starts.

Many unsuccessful attempts have been made

to calibrate aircraft equipment with seedtraps

or other means of estimating the number of

seeds distributed per acre. Sample variation has

been high, and it has seldom been feasible to

examine enough samples to insure accurate adjustment. As a workable alternative, the following step-by-step calibration procedure has been

developed from experience with many operational seedings. It is written for the helicopter

but with slight modification is applicable to

fixed-wing aircraft.

1. Select a likely meter opening and adjust

the meter on each hopper to this setting.

2. Place 20 pounds of seed in each hopper.

Load it in 5-pound increments, level, and mark

the hopper wall so that the amount remaining

can be estimated at any time during the operation.

3. Loosen the seed tubes from the slinger,

place a net bag over each, and make a 30-second

trial with the engine running. Waste air from

the cooling fan is normally used to move seed

through the tubes from hoppers to slinger. If

the system depends on ram air (created by

movement of the craft in flight), short tubes

should be available to permit gravity flow of

seed from the hoppers into the bags.

4. Weigh seed released from each hopper

separately to determine if meters are operating

at the same rate. Then calculate the rate per

acre from the total weight of seed released.

Acreage covered in any given time depends on

flying speed. At 60 m.p.h. it is .40chains_x 1.5 chains

= 6 acres in 30 seconds. For other operating

speeds, simply substitute the distance covered

(in chains) per 14 minute of operation. If the

sowing rate per acre is high or low, adjust

meter openings and repeat trials until the desired rate is attained.

5. If helicopter equipment is operating properly, the rate set in ground tests is usually

accurate. However, rate should be checked on

an area basis under actual operating conditions.

This can be done by seeding a selected area of

known dimensions and determining the weight

of seed expended ; or it can be accomplished by

starting the operation on flight strips of known

length, so that the acreage covered with a load

of seed can be computed. Usually, minor meter

adjustments are needed. As the job progresses,

it is advisable to maintain a constant check on

the seeding rate by recording the weight of seed

carried and acreage covered in each helicopter

load. Adjustments are also required occasionally to compensate for changes in humidity or

temperature, or for conditions that affect the

ability of the pilot to maintain the planned

ground speed.

Distributors on fixed-wing aircraft are calibrated similarly, but the static ground check is

not precise and is usually omitted if there is any

information or experience to suggest an approximate setting for the hopper gate. Rate of

seedflow into the distributor is affected by airspeed, vibration, and other features of the aircraft. Also, the hopper gates vary in size and

shape. Equipment for agricultural work must

be modified for best results in pine seeding.

Usually, metal plates are inserted to provide

short, wide apertures in place of long, narrow

ones. Calibration is checked on the basis of area

sown per load, in the same manner as described

50
for a helicopter except that the swath is only

1 chain wide. Interruptions in seedflow, due

either to presence of foreign material or bridging of the seed above the openings, is more common in fixed-wing craft than in helicopters, and

less easily detected in flight. Therefore, it is

essential to record the weight of seed in each

load and the area covered.

Frequently, aerial seeding is done on irregularly shaped tracts or on areas containing

stream bottoms and islands of pine reproduction where seedflow is normally cut off. In these

situations, continuous monitoring of sowing

rate is diflficult, and it is then doubly important

to have a measured calibration area.

Seed stoppages and mechanical breakdowns

occur with both types of aircraft. When not

detected promptly, they cause areas of unknown

size to be seeded too lightly or not at all. To

refly such areas at the full sowing rate is

wasteful of seed, and if done at a reduced rate

requires recalibration of the equipment. A compromise procedure frequently used is to refly

alternate strips at the full rate but at higher

altitude. This procedure does not insure full

and uniform coverage, but it does provide stocking on areas that are difficult to identify precisely.

Ground-operated machines for broadcasting

seed are also calibrated and checked by a system

of area control. The quantity of seed released

over an area of known size is determined, and

meters are adjusted until the desired rate is

reached. Hand-operated cyclone seeders sowing

a 14-chain (16i/^-feet) swath cover 1 acre each

V^ mile; tractor-mounted units have twice the

capacity, covering 4 acres per mile of operation.

Row-seeding machines are calibrated by

checking, on a hard surface, the number of

seeds dropped per chain of travel. This value

can be used to compute average spacing within the row and the number of seeds per acre

for a given interval between rows. Drop plates

on row seeders are usually modified to release

one or sometimes two seeds at a time. Adjustments in the rate of sowing are made by changing sizes among sprocket wheels that drive the

rotating plate.

PROTECTING SEED AND SEEDLINGS

A single prescription has not been devised

that will protect seed and seedlings completely

and under all conditions. In most operations

not much more than the repellent coating is

needed to assure success. But large losses occur

occasionally and hazards not forestalled by the

repellents may be encountered. Some hazards

can be avoided prior to sowing ; others may not

appear until seeds are on the ground or have

completed germination. Careful, systematic

examinations should be made during germination and in the first year, for losses can often

be reduced if timely action is taken. Such examinations are particularly important for localities

where there is little direct-seeding experience.

They should be included in the initial plan.

A method of establishing observation stations

for systematic appraisal of predator activity is

described in a later section. Here, emphasis

is on recognition of damage by animals, disease,

and weather. Detailed knowledge of hazards

will permit sowing rates to be adjusted to localities.

Birds

Despite the general effectiveness of the repellent, local losses to birds may occur—as

when the repellent coating is deteriorated by

heavy rains or repeated exposure to freezing

temperatures. Also, there is one common bird—

the crow—that has demonstrated indifference to

repellents, though its damage has not been observed frequently and is considered minor.

Sometimes migratory flocks of blackbirds or

other species may destroy the seed on small

areas. An understanding of bird attack is important in appraising damage to direct seeding.

Birds consume longleaf seeds either by

swallowing them whole or by shattering the

seedcoat and removing the endosperm. Meadowlarks, quail, mourning doves, and wild turkeys

normally take longleaf seeds whole. Fortunately,

repellent treatment is highly effective against

these species. Birds that shatter longleaf seeds

include common blackbirds and associates.

51
juncos, and sparrows. The repellents are effective against this group also, but when damage

occurs it is likely to be caused by these species.

Seeds of the other pines are small enough to

be swallowed whole by most birds.

Fragments of shattered seedcoats are good

evidence of bird attack. Generally damage is

concentrated in small areas. Remains of longleaf seeds look as if they had been struck repeatedly by a sharp object; seedcoats of other

species are usually broken into small pieces but

sometimes are simply split in half. Meadowlarks

often break off the wing stub of longleaf before

they eat the seed. Rodents also shatter seedcoats, but theirs is a tearing or cutting action

that can usually be distinguished on close inspection. Small ants occasionally cut the seedcoat; the fragments resemble those left by birds,

but uneaten portions of the endosperm frequently remain to identify the damage as insectcaused.

When seeds are eaten whole, bird activity

is difficult to detect. Indirect signs such as

tracks or droppings are often obscure, and if

present do not establish conclusively that feeding occurred. Direct observation of birds is

helpful but difficult, as some species feed during

the early morning or late evening and others,

moving in large flocks, may visit an area

sporadically. Whole seeds are also removed by

other animals, and an observer must guard

against blaming birds (and the repellent) when

other predators may be responsible. Observation stations, with seeds concentrated in a small

area, are invaluable for detecting seed losses

and identifying predators.

There is no effective control of bird attack

except patrolling, which is practical only on

small areas. The best defense is to insure that

all seeds are properly coated with repellent.

Small Mammals

Small seed-eating mammals common in southern forests include white-footed mice, harvest

mice, cotton rats, and squirrels. In some areas,

hispid pocket mice, pine voles, and golden mice

may also be prevalent {36, 77, 91, 97). The least

shrew, which is widely distributed and sometimes numerous in local areas, is included

through its role as a seed and seedling predator

is not fully documented. This is a secretive animal, seldom seen, difficult to trap, and hard to

evaluate in captivity.

Small mammals are far less numerous on

southern pine sites than in the West. All species

combined rarely number more than 10 individuals per acre, but such a population is

enough to destroy a seeding if repellents are not

used. A single mouse can eat 50 to 100 untreated seeds daily (fig. 38).

FS-SiaOI3

Figure 38.—Unless the repellent coating contains endrin, mice will destroy mucli of the seed.

52
Most mice are deterred by the repellents

when populations are normal and alternative

foods are adequate. Numerous cage tests have

shown that rodents stop eating treated seed

after sampling four or five. In hulling the seed,

they apparently ingest enough endrin to cause

aversion, and thereafter they reject treated seed

even when it is the only food offered. Mice cause

some damage in all seedings, but usually the loss

is serious only when the repellent coating is

depleted, when the seeded area is small, or when

small quantities of seed are used, as in spot

sowing.

Mice sometimes shatter and split seeds, but

often they merely bite off one end of the seedcoat and remove the endosperm (97) ; such

empty hulls therefore distinguish depredations

of mice from those of birds. Toothmarks and

clean cuts on the seedcoat fragments are other

evidence. Mice will, however, often remove seed

to a secluded location before eating it. If seed

is disappearing from observation stations and

mice are suspected, traps may be set.

Control of mice by poisoning has not been

tested widely on southern pine sites, but it is

doubtful if this approach would have much

value in direct seeding. On areas up to 40 acres,

studies of removal by trapping have shown

rapid reinvasion (36).

Squirrels are not repelled or deterred by the

repellent recommended here, or by any other

chemical that has been tested and can be used

operationally on seed. Where numerous, they

may destroy seedings completely, especially of

longleaf pine. They are not a problem on extensive open areas ; the most likely situation for

squirrel damage is where seeding is done under

large hardwoods or on small clearings surrounded by hardwoods. They usually destroy

seed in place. They are adept at robbing seedspots, which are useful therefore in preliminary

evaluation of a site to determine if a squirrel

problem exists.

Squirrel damage to longleaf seeds is distinctive: The fox squirrel removes one broad side

of the seedcoat; the eastern grey squirrel cuts

off the rounded end (fig. 39). Coats of smaller

seeds hulled by squirrels may resemble those

left by the white-footed mouse (97), and thus

identification of squirrel feeding may be difficult if other rodents are present. Elevated sta-

'^

^

1/

»

^/

\ *^H

FS.519014, 5190I5

Figure 39.—Repellent-coated longleaf seed hulls left by fox

squirrels (above) and eastern grey squirrels (below). Repellents

do not protect against these animals.

tions baited with other preferred foods such as

peanuts or pecans may be necessary to confirm

squirrel activity. The only effective control is

trapping or hunting—of course, in cooperation

with game authorities. Since the range of each

animal is relatively large, hunting is usually the

better method. It should be done before seeding

starts, and should be followed by frequent

checking during germination.

Cotton rats may kill young seedlings, especially of longleaf, by girdling them at the groundline. They ordinarily are not a nuisance where

site preparation has been adequate. If their

cover cannot be burned, the rats can be con68
trolled by placing strychnine bait in their runways. Such baits may also be used to reduce

infestations of pocket gophers, which feed on

the roots of established seedlings.

Large Animals

Of the large wild animals that have been

observed feeding on seed or seedlings, only the

cottontail rabbit appears to do widespread damage. It does not take treated seed but feeds on

cotyledons of germinating seedlings.

Loss to rabbits during or immediately after

germination frequently averages 25 percent of a

stand; occasionally it has been much higher.

Feeding usually occurs during late winter and

early spring, when other green vegetation is

scarce. It is most prevalent on areas fall-sown

with longleaf pine. Frequently the clipping is

done in a period of 1 to 3 weeks. Often it occurs

before the seedcoats drop off. Seedlings destroyed by rabbits are severed smoothly just

above the groundline; the stem and cotyledons

are then removed to a point about one-eighth

of an inch below the seedcoats (fig. 40).

Rabbits are fairly common on upland pine

sites, yet difficult to detect on a specific area

unless they are numerous (2-4). Their damage

can be very inconspicuous, especially when it

occurs after the seedcoats are off, because

nearly the entire plant is removed. There is also

little indirect evidence of their activity, such as

tracks or droppings, even when many seedlings

are removed from a small area. A series of

staked seedlings at representative locations offers the best means for appraising losses. These

seedlings must be inspected frequently, because

prompt action is necessary to prevent serious

losses. Removal by hunting or trapping is the

recommended control. Night hunting is especially effective. Permits for it and for off-season

hunting must be obtained from State game

authorities.

Raccoons, skunks, and opossums have damaged longleaf seedings in limited areas, but if

their populations are normal, these animals

seldom destroy enough seed to justify control.

When there are large unexplained losses from

observation stations, a local concentration of

one or more of these species should be suspected.

Hunting and trapping are the only practical

controls.

FS.5I90I6,SI90I7

Figure 40.—Clipping by rabbits usually occurs shortly before

seedlings shed their seedcoats (above); all that remains is a

short stub of stem and the untouched seedcoat containing cotyledon fragments (below).

Livestock

Entire seeded stands have been lost through

error in judging the intensity of use and damage by domestic animals. These losses begin

during germination and accumulate over the

first year or two.

Most young stands can tolerate moderate

grazing by cattle. Generally, moderate grazing

is defined as the intensity at which approximately one-half of the annual production of

forage is utilized. On open areas, this is achieved

with 30 to 40 head of cattle per section of land

(26). Sites occupied by hardwoods have lower

carrying capacities, and the distribution of

grazing on them is likely to be spotty. After

hardwoods are treated, cattle concentrate under

54
the deadened trees, where the seedlings are also

apt to be concentrated (fig. 41). Management of

grazing on hardwood-dominated sites is not

simple; often the best course is to exclude

animals for the initial 2 or 3 years.

Prepared seedbeds of any kind attract cattle,

usually early in the first season when seedlings

are most susceptible to trampling. On areas

open to unrestricted grazing, temporary fencing

may be needed. Intensity of seedbed treatment,

number of cattle in the vicinity, and opportunities for diversionary burns are factors helpful

in deciding if fencing is desirable.

Range hogs must be excluded from longleaf

pine regeneration, and they are destructive,

directly or indirectly, to other species as well.

Hogs eat treated seed but seldom in large quantities. They feed heavily on longleaf seedlings

and often cause serious damage by uprooting or

burying other seedlings in their normal foraging for food, especially on disked or furrowed

sites. Total exclusion of hogs, sheep, and goats

by fencing or other means is strongly suggested

by experiences with seedings of all species.

Insects

Several insect pests may be troublesome.

Though it is doubtful if any have been primarily responsible for a seeding failure, they

reduce yields and create undesirable variations

in tree distribution.

For convenience, insect predators can be

classified into two broad groups: those that

move seed or seedlings to their nest sites and

those that destroy them in place. Short-tailed

crickets and harvester ants move ungerminated

seed into underground chambers; the crickets

occasionally take germinating seed as well. The

Texas leaf-cutting ant (town ant) cuts emerging radicles and cotyledons from germinating

seed, moving them to underground chambers

Figure 41.—Cattle are attracted to areas where hardwoods have been deadened, and concentrated grazing endangers seedling stands.

55
and leaving the expended seed behind. Predators that destroy seed or seedlings in place

include minor species of ants and several miscellaneous pests.

Short-tailed crickets are widely distributed

in Louisiana; extent of their occurrence elsewhere is not known. They are especially prevalent on poorly drained sites. Heavy populations may be damaging to a direct seeding;

concentrations of 10,000 per acre have been

reported, but densities of 2,000 to 5,000 per

acre are more common.

Small mounds of soil on the surface are signs

of their presence (fig. 42). Excavation below a

mound reveals a single tunnel leading to a food

storage chamber 1 to 2 inches below the surface.

The adults are usually found singly at the bottom of a 12- to 18-inch gallery running downward from the food storage chamber. Crickets

may forage and raise fresh mounds in a single

night, then remain inactive for long periods.

Their mounds are inconspicuous when washed

down by rain ; heavy infestations are apparent

only during periods of activity. When foraging,

a cricket will move seed and occasionally germinating seedlings into the food chamber, along

with bits of green vegetation (86). Feeding on

treated seed usually kills crickets, but before

dying an individual may move several seeds into

its burrow.

Harvester ants of four species are found

within the southern pine region. The Florida

harvester ant occurs in sandy soils from south

Mississippi eastward to the Atlantic coast. The

FS-5I9OI0

Figure 42.—The short-tailed cricket lives in an underground burrow marked by a small mound of excavated soil.

56
other three, the western, red, and Comanche

harvester ants, live in similar soils in north

Louisiana and Texas. They are large, fastmoving ants that have underground nests in

which they store seeds of many species, including pines. A typical surface mound is illustrated

in figure 43. Densities of two to five nests per

acre are common on some sites. The ants sometimes remove treated seeds ; their potential for

damage has not been fully evaluated.

Several insects or other pests destroy seed or

seedlings in place. None can be classified as

generally serious, though each is capable of

causing heavy damage in small areas. Following is a list of those that have been identified :

Small red and black ants: Enter germinating

seed and eat the endosperm.

Small fungus-growing ant (Trachymyrmex) :

Suspected of cutting cotyledons of newly

germinated seedlings.

Slugs, snails: Feed on emerging radicle of

treated or untreated seed, cutting it flush

with the seedcoat. Occasionally mine lower

one-third of endosperm.

Millipedes: Feed on untreated seed; there

have been few instances of damage to

treated seed. Portions of a cotyledon are

taken occasionally.

Cutworms: Sever cotyledon-stage seedlings

at the groundline, leaving them in place or

partially consuming them.

White-fringed beetles: Destroy first-year

seedlings by feeding on the roots. Found

under sod on abandoned fields.

White grubs: Destroy or stunt first-year seedlings by feeding on the roots. These, too,

are most prevalent on old fields.

With present knowledge, direct control of

insect predators is practical, and essential, only

for the Texas leaf-cutting ant. This pest must

» *ii^

,\'-"''

4^.-^ ^íh V?«'^:íJm/-^SU

FS-S19020

Figure 43.—The nest of the harvester ant can usually be identified by a ring of charred debris around the entrance hole.

57
be eliminated well in advance of sowing, for it

can destroy all germinating seeds and seedlings

within range of its nest. An ant colony can be

eliminated with a single application of a special

mirex bait {27), or by fumigation with methyl

bromide. When populations of other insects—

particularly crickets and harvester ants—are

heavy, the most practical course is to increase

sowing rates 10 to 20 percent.

Disease

Damping-off, caused by any one of several

fungi, is the only disease of concern in direct

seeding. It is primarily a nursery disease, and

there have been few instances of extensive

damage to field-sown seedlings—a fortunate

situation, since control is difficult and uncertain

even in intensely managed nursery beds. The

disease appears during germination or soon

after. The stems of infected seedlings wilt and

shrivel near the groundline; the affected part

of the stem turns dark. Longleaf seedlings flatten out on the ground, seedlings of other species

topple over.

In preemergence damping-off, the embryo or

radicle is destroyed before the seedling appears.

The thiram used in the repellent coating is basically a fungicide, and probably controls some of

the organisms causing damping-off. Such an

effect is suggested by field comparisons in

which coated seeds have consistently germinated better than untreated seeds on protected

spots where prédation by animals and insects

was minimized.

Weather

Drought, seed movement and silting by heavy

rain, and frost heaving are the main effects of

adverse weather. They are in some respects inherent risks, though loss from drought and

water can be lessened by proper site and seedbed preparations.

Moving surface water from high-intensity

rains may displace germinating seedlings before the radicles are firmly anchored in the soil.

Losses are most likely on steep terrain burned

just before seeding. If burning can be scheduled

6 to 8 months ahead of sowing, the light regrowth of vegetation usually reduces water

movement enough to prevent serious loss. The

large, buoyant seeds of longleaf pine are most

easily dislodged by moving water. But a light

1-year-rough is a good seedbed for this species.

Frost heaving has been reported as causing

excessive seedling losses on some soils, particularly those that are bare or poorly drained, or

have a high proportion of clay in the surface

layer. Repeated freezing and thawing of the

soil lifts the seedlings and exposes the roots.

Most losses have been to longleaf pines sown

in the fall, and for this species the only preventive is to retain some cover on the site or to

sow in spring. On some sites damage may also

occur in the first winter after spring germination, and here sowing rates should be high

enough so that stocking will be adequate even

if there is some loss.

APPRAISALS

Seed losses begin on the day of sowing and

continue throughout the germination period.

Then attrition of seedlings starts. A successful

seeding is one in which losses are minimized,

so that adequate first-year stocking is achieved

with the least amount of seed. For consistent

success, a landowner must have reliable estimates of controllable losses, of stand density,

and of losses from uncontrollable factors such

as drought.

Two or three estimates are normally made

during the establishment period. They are : (1)

predator activity before and during germination, (2) initial stocking, and (3) stocking at

the end of the first year. The second evaluation

is often omitted in routine seeding when initial

yields are not required to evaluate sowing rates

or site treatments. A stocking survey may also

be needed at the end of the second year or later

if heavy losses from cattle, rabbits, or dry

weather are suspected.

Direct seeding often has been done without

adequate appraisals. Some well-stocked stands

have been "discovered" several years after a

58
cursory initial examination caused them to be

written off as failures. Worse, perhaps, are

situations in which seeded areas are carried on

the record as stocked when, in fact, the stands

are inadequate. In these cases, opportunities

for reseeding are lost and expensive site preparation must often be done again.

Estimating Predator Activity

Before & During Germination

Observation stations, where repeated examinations can be made, are essential for detecting

predator activity in initial seeding trials. Because the seeds are exposed and concentrated,

prédation on these plots may be greater than

elsewhere. Nevertheless, the stations provide

the best reference points for determining

whether important predators are at work. Occasionally, they must be supplemented by other

means when unusual losses are found. After

several successful sowings the stations usually

can be discontinued.

An effective observation station consists of an

identification stake and two small cleared spots

containing 25 exposed seeds each and located

at least 3 feet from the stake in opposite directions (fig. 44). An additional screened spot

with 10 seeds is usually added nearby to provide an estimate of maximum field germination.

All spots should be sown with treated seed from

the same lot used on the general area. Small

seeds, as of loblolly or shortleaf pine, are easily

lost from view if moved by water or covered

by soil and debris. Some of the difficulty can be

overcome by placing them on small concave

disks of window screen laid in contact with the

soil. Also, the number of seeds per spot can be

increased substantially. Increasing the number

precludes accurate counting but still permits

gross estimates of predator activity.

Concentration of the seed in small spots allows rapid examination, thus permitting placement and examination of an adequate number

of stations. It also increases the likelihood that

predators will leave evidence of their visit.

Simultaneous destruction of both spots at a station indicates a higher level of predator activity

than single-spot attacks.

The number of stations varies with size of

Figure 44.—A typical observation station, consisting of screened

and exposed seeds placed near an Identification stake.

the seeding and with the number of distinct

cover conditions. Fifty well-dispersed stations

are usually adequate for areas of 100 to 1,000

acres in size. More are needed on larger areas

or one where there are wide differences in site

or cover conditions. For small areas the number

can be scaled down, but 15 is about the minimum.

The frequency at which the stations are examined may range from daily to weekly. The inter-
val need not be fixed, but examinations more

than a week apart tend to defeat their purpose.

The usual procedure is to start on a weeklyschedule, then shorten the intervals when a

significant amount of damage is detected or

germination begins. Only in rare situations are

daily observations needed; an example would

be while rabbits are being controlled on areas

where their damage to seedlings has been detected.

A simple record form is helpful in maintaining continuity of observations for each station.

The number of seeds destroyed or missing between examinations should be recorded, and

notes should be made on evidence left by the

predator. Other information to be documented

includes apparent condition of the repellent

coating, number of undamaged seeds still visible, progress of germination, and insect activity.

Germinated seedlings should be marked with

pins, because seedlings are often destroyed with

very little evidence remaining. Spots losing

seeds early in the observation period should be

reseeded to maintain their usefulness for detecting additional damage.

Some losses can be expected on any series of

observation stations, but it is difficult to say

how much damage must occur to indicate serious prédation. Usually a minor loss of seed

occurs during the initial 2 weeks. The loss may

include all of the 25 seed samples from some

spots. Seed fragments or damaged spots usually

indicate rodent activity. This activity normally

stops after the initial attack, indicating that a

local animal has been conditioned by the repellent against further feeding.

Initial losses are of minor concern unless they

occur on a majority of the stations and unless

they continue. Then, the possibilities of a high

rodent population or damage by migratory

birds should be investigated. Heavy and sudden

losses occurring late in the germination period

usually signify migratory birds, or if germinating seedlings are removed, rabbits. Both agents

should be checked by direct observation at times

of the day when they are most likely to be

feeding. Rabbits, of course, are seldom active

during daylight.

Data from the observation stations should not

be regarded as providing a true sample of conditions on the seeded area. This is not the purpose of the stations. True samples, i.e., random

plots of a prescribed size on which sown seeds

are observed in place, require considerable effort. Observation stations simply provide a

quick means of detecting damage. When damage does occur, further checking of the seeded

area is required to evaluate it properly. Supplemental methods are sometimes needed in initial

seeding trials to identify a predator or measure

the extent of its damage. They include trapping

with live or snap traps, night observation with

a light, or staking of established seedlings.

Seedling Inventories

The first year is critical for all southern pines.

New seedlings are highly vulnerable to drought

before their root systems are well formed. Mortality varies greatly by climate, soil type, and

cover conditions. Climate is the most important

single factor. On flatwoods sites in the Southeast, summer rainfall is usually well distributed

and mortality normally averages less than 5

percent. In the West Gulf region, where summer droughts of 4 to 8 weeks' duration are common, mortality may reach 70 percent in dry

years, even on well-prepared seedbeds.

At least two seedling inventories are advised

—one at the beginning of summer when germination is completed, the other at the end of the

first growing season when danger of mortality

from drought is past. The early inventory indicates the eflSciency of repellents in new localities. The second usually estimates overall

success, for loss after the first year is normally

low. The difference between the first and second

inventories represents first-year mortality, a

highly useful statistic in adapting future operations to local conditions. Occasionally losses are

heavy between the first and second years, and

then a third inventory may be desirable.

Seeding success can be judged by number of

seedlings per acre and by distribution of these

seedlings; the two values are closely related.

Tree percent, the ratio of seedlings to seed, is

often calculated too. It should be about 25 in

early summer (that is, one seedling for four

seeds) ; if it is substantially lower there is good

chance that something unusual has occurred.

Stocking, a measure of seedling distribution,

is normally expressed as the percent of milacre

(1/1,000-acre) sample plots having one or more

pines. Land managers judge success most fre60
quently by the stocking present after the first

growing season. In broadcast sowing, distribution approaches 100 percent when seedlings

number 5,000 to 6,000 per acre. It may drop to

about 50 percent with 1,000 seedlings per acre.

When densities are between 1,500 and 3,500

seedlings per acre the usual range of stocking

is between 60 and 80 percent (ñg. 45). A commonly accepted minimum criterion for success

is 55 percent.

Both number of seedlings per acre and stocking can be determined for the same set of sample plots. Little extra time is required to count

all seedlings on a milacre once the plot has been

established. The two values allow better interpretation of results than does stocking alone.

For example, low stocking but a high number of

seedlings per acre suggests either non-uniform

sowing or uneven germination or survival.

Circular milacre plots are convenient for

sampling broadcast seedings, as only a sweep

of the plot radius (44.7 inches) is necessary to

delineate the plot boundary. Plots are usually

on a systematic grid, with distance between

plots and between lines of plots dependent on

the number taken. Plot centers must be established without bias, plot areas must be carefully

searched for seedlings, and borderline seedlings

must be accurately classified as on or off the

plots. The mean number per plot multiplied by

1,000 provides an estimate of number per acre.

Stocking, based on 1,000 perfectly distributed

6P00-

5^

^4,000

I

2,000 -

Y = 1.0908 -0.0647 X + 0.0012 X'

r = 0.845

20 40 60 80

PERCENT OF MILACRE PLOTS STOCKED

100

Figure 45.-~Relationship between number and stocking of seedlings

obtained from broadcast sowing. Data are from 209 research

and operational seedings.

seedlings per acre, is expressed as the percentage of sample plots with at least one seedling.

When stocking alone is desired, the field procedure is the same except that searching on a

plot is discontinued after the first seedling is

found.

The number of sample plots required depends

on desired accuracy and the expected plot-toplot variation (expressed as coefficient of

variation). Experience has shown that the

coefficient of variation for average number of

seedlings per plot is close to 100 percent on

milacres sampling broadcast seedings. This

means that there is a 1:1 ratio between the

mean and its standard deviation. For example,

a stand with a mean value of four seedlings per

milacre would have two out of three sample

plots falling in the range of 4 ±: 4, or from zero

to eight seedlings per plot.

The intensity of sampling for 67-percent reliability is calculated as ( coefficient of variation X2 ^

•^ V desired accuracy /

number of sample plots. Thus, if an accuracy of

±1 10 percent is required and a coefficient of

variation of 100 percent is assumed, the number

of sample plots needed would be ( -~— y or 100.

Generally, 100 plots are adequate for sampling

seedling numbers on areas up to several thousand acres. If separate estimates are wanted for

subunits, approximately 100 sample plots will

be required for each. In practice, subunits are

usually sampled with a smaller number of plots ;

the resulting error of estimate is larger, but the

combined total for all subunits gives a sufficiently accurate estimate of the whole seeding.

Such sampling allows rough identification of

subunits that may require supplemental seeding. These subunits are then sampled more

intensively before a final determination is made.

A modification in sampling procedure is

desirable for areas that are disked in strips and

sown broadcast. Seedlings on the undisked portions contribute to the stand, but may differ in

number and distribution from seedlings on

disked portions. Both populations can be determined simultaneously by examining a pair of

sample plots at each location—one on the disked

strip and one on the untreated balk. Stocking

and average number of seedlings per acre on

each type of seedbed are computed separately,

then weighted by the proportion of area in each

category for the estimate of overall stocking. If

unknown, the percent of the area disked can be

61
estimated by measuring edge-to-edge distances

between strips at each plot location.

On tracts seeded in rows or strips, rather

than broadcast, the sample plot becomes a linear

segment of the row. The procedure is to establish, on regular transect lines, a plot consisting

of two adjacent 6.6-foot segments. A location

marking the common boundary of the two subplots is selected in an unbiased manner. The

total number of seedlings on each subplot is recorded. Finally, the distances from the center

of the sampled strip or row to the center of each

adjoining one are measured at each location.

The estimate of seedlings per gross acre is computed by multiplying the mean stocking per

sample location (both 6.6-foot subplots) by

For example, if the 3,300

average distance between centers * mean stocking per 13.2-foot sample plot is 12

and the strip or row centers average 16.5 feet

apart, stand density is ^^-^|^^=: 2,400 seedlings

per gross acre. The constant, 3,300, is derived

by dividing the number of square feet per acre

(43,560) by the total length of the sample segment (13.2 feet). Sampling with a plot length

other than 13.2 feet simply requires computing

an appropriate constant.

Stocking percent is derived by multiplying

the percent of subplots (6.6-foot segments) stocked with one or more seedlings by

:rr-2—^-i ;^. Obviously, any strip average distance between centers J 7 *7 MT

or row spacing over 6.6 feet reduces the maximum stocking that can be attained. If the average interval between centers is 13.2 feet, full

sample-plot stocking will be 100 ( —j||— ) or 50

percent.

Stocking of spot-sown tracts is normally estimated as the proportion of spots with at least

one seedling. The total yield of seedlings may

also be tallied to evaluate sowing rates, though

more than one seedling per spot is excess (13),

Occasionally, seeded spots are difficult to relocate after germination is complete. In these

cases, sampling methods described for broadcast-sown areas must be used.

LITERATURE CITED

(1) Anonymous.

1960. A wide spectrum repellent for rodents and wildlife. DuPont Agr.

Newsletter 28(3) :9.

(2) Abbott, H.G.

1961. Direct seeding of conifers. Northeast. Logger 10(4):20.21, 32-33,

37.

(3) Abbott, H. G., and Hilton, R. L.

1965. Seeding white pine under poor

quality hardwoods. In Direct seeding in the Northeast—1964. A

symposium, pp. 34-37. Univ. Mass.

(4) Asher,W.C.

1964. A formula for estimating slash

pine seed yields. J. Forest. 62:37-

39.

(5) Baldwin, H.I.

1965. Summary of direct seeding in New

Hampshire 1924-62. In Direct

seeding in the Northeast—1964.

A symposium, pp. 59-64. Univ.

Mass.

(6) Barnett,J.P.

1964. Stored longleaf seed successfully

direct seeded. USDA Forest Serv.

Tree Planters' Notes 65, pp. 3-5.

(7) Barnett, J. P., and McLemore, B. F.

1966. Repellent-coated pine seed can be

stored. Forest Farmer 25(9) :14.

(8) Barrett, J. P.

1963. Slash pine gum flow unaffected by

seed origin. Forests and People

13(2):18-19.

(9) Beers, W. L., Jr.

1959. Sowing criteria by sites. In Direct

seeding in the South. A symposium, pp. 129-135. Duke Univ.

(10) Boyer,W.D.

1964. Longleaf seed losses to animals on

burned seedbeds. USDA Forest

Serv. Res. Note SO-6, 3 pp. South.

Forest Exp. Sta., New Orleans, La.

(11) Bramlett, D. L., and Hutchinson, J. G.

1964. Estimating sound seed per cone in

shortleaf pine. USDA Forest Serv.

Res. Note SE-18, 2 pp. Southeast.

Forest Exp. Sta., Asheville, N. C.

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(12) Burns, R. M.

1961. Seed sowing tool USDA Forest

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3-4.

(13) Campbell, T. E.

1964. Development of slash pine on

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822.

(14) Cassady, J. T., Hopkins, W., and Whitaker, L. B.

1955. Cattle grazing damage to pine

seedlings. USDA Forest Serv.

South. Forest Exp. Sta. Occas.

Pap. 141,14 pp.

(15) Cobb,H.C.

1959. Seed collection and processing. In

Direct seeding in the South. A

symposium, pp. 40-46. Duke Univ.

(16) Cooper, E.N.

1959. The industrial need for direct

seeding. In Direct seeding in the

South. A symposium, pp. 7-12.

Duke Univ.

(17) Cooper, E.N.

1961. Tussock seeding and mound planting. USDA Forest Serv. Tree

Planters' Notes 46, pp. 5-7.

(18) Cotrufo,C.

1962. Pretreatment of eastern white

pine seed. USDA Forest Serv.

Southeast. Forest Exp. Sta. Res.

Notes 176, 2 pp.

(19) Croker, T. C, Jr.

1960. The H-C furrow seeder. USDA

Forest Serv. Tree Planters' Notes

43, pp. 15-16.

(20) Derr,H.J.

1960. Preventing sticker failures in direct seeding. USDA Forest Serv.

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(21) Derr,HJ.

1963. Better repellent for direct seeding. USDA Forest Serv. Tree

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(22) Derr,H.J.

1964. New repellent formulation for direct seeding. J. Forest. 62:265.

(23) Derr, H. J., and Enghardt, H.

1960. Is geographic seed source of slash

pine important? South. Lumberman 201(2513) : 95-96.

(24) Derr, H. J., and Mann, W. F., Jr.

1959. Guidelines for direct-seeding longleaf pine USDA Forest Serv.

South. Forest Exp. Sta. Occas.

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L.

1961. Polyethylene bag storage versus

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and loblolly pine. USDA Forest

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15-16.

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1963. Supplemental feeding increases

beef production on bluestem-longleaf pine ranges. La. State Univ.

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1966. Texas leaf-cutting ant controlled

with pelleted mirex bait. J. Econ.

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1959. Seeded and planted pines grow at

similar rates. USDA Forest Serv.

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1965. Effects of storage treatments on

the ripening and viability of Virginia pine seed. USDA Forest

Serv. Res. Note NE-31, 6 pp.

Northeast. Forest Exp. Sta., Upper Darby, Penn.

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1964. The effect of pretreatment on

germination of slash pine seed.

Forest. Comm. New South Wales

Res. Note 14,11 pp.

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1965. Germination of eastern white pine

seed as inñuenced by stratification. USDA Forest Serv. Res. Pap.

NE-36, 9 pp. Northeast. Forest

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1958. Virginia pine seeded in Tennessee.

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1960. Direct seeding white pine. USDA

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1964. Immediate release needed for

maximum growth of seeded loblolly pine. USDA Forest Serv.

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1964. Small-mammal species and populations in the loblolly-shortleaf

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Forest Res. Counc. Res. Pap. 40,

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1959. Site preparation for direct seeding in the Piedmont and mountain

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1962. Soil cover aids germination of pine

seed on sandy sites. USDA Forest

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Lw

1959. Storing loblolly pine seed in polyethylene bags as a substitute for

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496.

(41) Jarrett,T.W.

1964. Depth of planting affects germination of white pine seed. J. Forest. 62:502.

(42) Jarvis, W. T., and Beers, W. L.

1965. Reclamation of a wasteland in

Central Gulf Coastal Florida. J.

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(43) Jones, E. P., Jr.

1963. A test of direct seeding depths for

slash and longleaf pine. USDA

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(44) Jones, L.

1962. Recommendations for successful

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1963. Germination of repellent-treated

southern pine seed before and

after storage. USDA Forest Serv.

Res. Note SE-15, 4 pp. Southeast.

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(46) Jones, L.

1966. Storing pine seed : What are best

moisture and temperature conditions? Ga. Forest Res. Counc. Res.

Pap. 42, 8 pp.

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1962. Comparison of early development

of planted and direct seeded slash

pine. Union Bag-Camp. Pap. Corp.

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1960. Stratifying pine seeds in plastic

bags. Amer. Nurseryman 111

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(49) Lewis, C.H.

1959. The economic advantage of seeding over planting on large ownerships in Louisiana. In Direct seeding in the South. A symposium,

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(50) Little, S., and Somes, H. A.

1964. Root systems of direct-seeded and

variously planted loblolly, shortleaf, and pitch pines. USDA Forest Serv. Res. Pap. NE-26, 13 pp.

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(51) McLemore, B. F.

1959. Cone maturity affects germination of longleaf pine seed. J. Forest. 57:648-650.

(52) McLemore, B. F.

1961. Prolonged storage of longleaf

cones weakens seed. USDA Forest

Serv. South. Forest Exp. Sta.

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(53) McLemore, B. F.

1961. Small, fast-drying cone kiln.

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Notes 47, pp. 9-12.

(54) McLemore, B. F.

1961. Storage of longleaf pine seed.

USDA Forest Serv. Tree Planters'

Notes 47, pp. 15-19.

(55) McLemore, B. F.

1962. Predicting seed yields of southern

pine cones. J. Forest. 60:639-641.

(56) McLemore, B. F., and Barnett, J. P.

1966. Storing repellent-coated southern

pine seed. J. Forest. 64:619-621

(57) McLemore, B. F., and Czabator, F. J.

1961. Length of stratification and germination of loblolly pine seed. J.

Forest. 59:267-269.

(58) McLintock, T. F.

1942. Stratification as a means of improving results of direct seeding

of pines. J. Forest. 40:724-728.

(59) McQuilkin, W. E.

1959. Establishing white pine on open

land. In What's known about managing eastern white pine, pp. 31-

44. USDA Forest Serv. Northeast.

Forest Exp. Sta., Sta. Pap. 121.

(60) McReynolds, R. D.

1960. Mortality of newly germinated

southern pine seedlings following

inundation. USDA Forest Serv.

Tree Planters' Notes 43, pp.

23-25.

(61) Maki,T.E.

1968. Drainage and soil moisture control

in forest production. In Ecology

of southern forests, pp. 139-153.

La. State Univ. 17th Annu. Forest. Symp. Proc. 1968. La. State

Univ. Press.

(62) Maki, T. E., and Mann, W. F., Jr.

1951. Some effects of sheep grazing on

longleaf pine. J. Forest. 49:278-

281.

(63) Malac,B.F.

1960. More on stratification of pine seed

in polyethylene bags. USDA Forest Serv. Tree Planters' Notes 42,

pp. 7-9.

(64) Mann, W. F., Jr.

1952. Stratified pine seed for direct

seeding. USDA Forest Serv. Tree

Planters' Notes 11, p. 3.

(65) Mann, W. F., Jr.

1959. Preparing seed for direct seeding.

In Direct seeding in the South. A

symposium, pp. 52-61. Duke Univ.

(66) Mann, W. F., Jr.

1962. Tools for direct seeding. Forest

Farmer 21(5): 13-16.

(67) Mann, W. F., Jr.

1965. Progress in direct-seeding the

southern pines. In Direct seeding

in the Northeast—1964. A symposium, pp. 9-13. Univ. Mass.

(68) Mann, W. F., Jr., and Burkhalter, H. D.

1961. The South's largest successful

direct seeding. J. Forest. 59:

83-87.

(69) Mann, W. F., Jr., and Burns, E. B.

1965. Direct seeding for the small landowner. Forest Farmer 25(3): 7,

14.

(70) Mann, W. F., Jr., and Derr, H. J.

1955. Not for the birds. USDA Forest

Serv. Tree Planters' Notes 20, pp.

3-6.

(71) Mann, W. F., Jr., and Derr, H. J.

1961. Guidelines for direct-seeding loblolly pine. USDA Forest Serv.

South. Forest Exp. Sta. Occas.

Pap. 188, 23 pp.

(72) Mann, W. F., Jr., and Derr, H. J.

1964. Guides for direct-seeding slash

pine. USDA Forest Serv. Res. Pap.

SO-12, 27 pp. South. Forest Exp.

Sta., New Orleans, La.

(73) Mann, W. F., Jr., Derr, H. J., and Meanley, B.

1956. A bird repellent for direct seeding

of longleaf pine. J. Forest. 54:

190-191.

(74) Maple, W.R.

1961. Treated shortleaf pine seed can

be stored. USDA Forest Serv.

South. Forest Exp. Sta. South.

Forest. Notes 136.

(75) Maxwell, K. F., Cech, F. C, and Driver,

C.H.

1960. Covering southern pine seed. Forest Farmer 20(2): 9, 12.

65
(76) Meade,F.M.

1963. Storage of repellent-treated pine

seeds. Ark. Farm Res. 12(6) :5.

(77) Mignery, A. L., and Yeatman, H. C.

1960. Mice hinder pine seeding on Cumberland Plateau. USDA Forest

Serv. South. Forest Exp. Sta.

South. Forest. Notes 129.

(78) Miller, S.R.

1957. Germination of slash pine seed

following submergence in water.

Union Bag-Camp Pap. Corp.

Woodland Res. Notes 3, 2 pp.

(79) Miller, S.R.

1966. Prescription direct seeding as an

operational program. Proc, Direct

seeding workshops, Alexandria,

La., and Tallahassee, Fla., pp. 99-

109. USDA Forest Serv., Atlanta,

Ga.

(80) Phares, R. E., and Liming, F. G.

1960. Comparative development of

seeded and planted shortleaf pine

on a forest site in the Missouri

Ozarks. J. Forest. 58:957-959.

(81) Phares, R. E., and Liming, F. G.

1961. Development of shortleaf pine

seedlings in seeded spots. J. Forest. 59:515-516.

(82) Phares, R. E., and Liming, F. G.

1961. Shortleaf pine direct-seeding success affected by month of seeding,

release method, and weather. J.

Forest. 59:804-807.

(83) Richardson, B. Y.

1965. New tools for direct seeding.

South. Lumberman 211(2632):

150-151.

(84) Roe,E. L

1948. Viability of white pine seed after

10 years of storage. J. Forest. 46:

900-902.

(85) Royall, W. C, Jr., and Ferguson, E. R.

1962. Controlling bird and mammal

damage in direct seeding loblolly

pine in east Texas. J. Forest. 60:

37-39.

(86) Russell, T.E.

1958. Cricket hazard. Forest Farmer

17(12):12-13,15.

(87) Russell, T.E.

1964. From oak-hickory tie orchards to

profitable white pine—by direct

seeding. USDA Forest Serv. Tree

Planters' Notes 67, pp. 19-21.

(88) Russell, T. E., and Rhame, T. E.

1961. The advantages of disking for

slash seeding. Forests and People

11(1):12-13.

(89) Scheer, R. L., and Woods, F. W.

1959. Intensity of preplanting site preparation required for Florida's

sandhills. USDA Forest Serv.

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Pap. 168,12 pp.

(90) Seidel, K.W.

1963. Germination of treated shortleaf

pine seed. USDA Forest Serv.

Res. Pap. CS-5,12 pp. Cent. States

Forest Exp. Sta., Columbus, Ohio.

(91) Shadowen, H. E.

1963. A live-trap study of small mammals in Louisiana. J. Mammalogy

44:103-108.

(92) Shipman,R. D.

1963. Seeding depth—its inñuence on

establishment of direct-seeded

pine in the South Carolina sandhills. J. Forest. 61:907-912.

(93) Snyder, E. B., Wakeley, P. C, and Wells,

0.0.

1967. Slash pine provenance tests. J.

Forest. 65:414-420.

(94) Sower, D. W., Jr.

1964. Suggested guidelines for direct

seeding Virginia pine in West

Virginia. North. Logger 12(8):

12-13, 36-39.

(95) Sowers, D. W., Jr.

1965. Direct seeding experiments with

Virginia pine in West Virginia. In

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1964. A symposium, pp. 68-71.

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(96) Squillace, A. E.

1966. Geographic variation in slash pine.

Forest Sei. Monogr. 10, 56 pp.

(97) Stephenson, G. K., Goodrum, P. D., and

Packard, R. L.

1963. Small rodents as consumers of

pine seed in east Texas uplands.

J. Forest. 61:523-526.

66
(98) Sucoff, E. I., and Church, T. W., Jr.

1960. Seed production and dissemination

by Virginia pine. J. Forest. 58:

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(99) USDA Forest Service.

1965. Silvics of forest trees of the

United States. USDA Agr. Handbook 271, 762 pp.

(100) VanHaverbeke, D. F., and Barber, J. C.

1964. Seed crop estimation in a loblolly

pine seed production area. Ga.

Forest Res. Counc. Res. Pap. 21,

5 pp.

(101) Wakeley,P. C.

1954. Planting the southern pines.

USDA Agr. Monogr. 18, 233 pp.

(102) Webb, C. D., and Hunt, D. L.

1965. Seed crop estimation in a slash

pine seed production area. Ga.

Forest Res. Counc. Res. Pap. 28,

5 pp.

(103) Wells, 0.0.

1969. Results of the Southwide Pine

Seed Source Study through 1968-

69. Tenth South. Forest Tree

Impr. Conf. Proc. 1969: (inpress).

(104) Wells, 0. 0., and Wakeley, P. C.

1966. Geographic variation in survival,

growth, and fusiform-rust infection of planted loblolly pine. Forest Sei. Monogr. 11, 40 pp.

(105) Wenger,K.F.

1953. How to estimate the number of

cones in standing loblolly pine

trees. USDA Forest Serv. Southeast. Forest Exp. Sta. Res. Notes

44,2 pp.

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1959. Seed sources for direct seeding. In

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¿/4ep^4áo¿a!e4^a^

FOLLOW THK LABEL

U.S. DIPAIITMENT OF ACIKUITURE

67
Pesticides used improperly can be injurious to man, animals, and plants.

Follow the directions and heed all precautions on the labels.

Store pesticides in original containers under lock and key—out of the reach

of children and animals—and away from food and feed.

Apply pesticides so that they do not endanger humans, livestock, crops, beneficial insects, fish, and wildlife. Do not apply pesticides when there is danger

of drift, when honey bees or other pollinating insects are visiting plants, or in

ways that may contaminate water or leave illegal residues.

Avoid prolonged inhalation of pesticide sprays or dusts; wear protective

clothing and equipment if specified on the container.

If your hands become contaminated with a pesticide, do not eat or drink

until you have washed. In case a pesticide is swallowed or gets in the eyes,

follow the first aid treatment given on the label, and get prompt medical

attention. If a pesticide is spilled on your skin or clothing, remove clothing

immediately and wash skin thoroughly.

Do not clean spray equipment or dump excess spray material near ponds,

streams, or wells. Because it is difficult to remove all traces of herbicides from

equipment, do not use the same equipment for insecticides or fungicides that

you use for herbicides.

Dispose of empty pesticide containers promptly. Have them buried at a sanitary land-fill dump, or crush and bury them in a level, isolated place.

NOTE: Some States have restrictions on the use of certain pesticides. Check

your State and local regulations. Also because registrations of pesticides are

under constant review by the U. S. Department of Agriculture, consult your

county agricultural agent or State Extension specialist to be sure the intended

use is still registered.

^ U.S. GOVERNMENT PRINTING OFFICE: 1971^^—406-31S

68