s 't 0^)

H PRODUCTION EAST OF

THE ROCKY MOUNTAINS

ffyly,jihK. ^^0

IS. DEPARTMENT OF AGRICULTURE
PRECAUTIONS

Pesticides are poisonous to man and animals. Use them only

when needed and handle them with care. Follow the directions

and heed all precautions on the labels.

Keep pesticides in closed, well-labeled containers in a dry place.

Store them where they will not contaminate food or feed, and where

children and pets cannot reach them.

Avoid repeated or prolonged contact of pesticides with the skin.

Avoid inhalation of pesticide dusts or mists.

Avoid spilling pesticides on your skin, and keep them out of the

eyes, nose, and mouth. If any is spilled on skin or clothing, wash

it off the skin and change clothing immediately.

Wlien handling pesticides, wear clean, dry clothing.

Wash your hands and face before eating or smoking and immediately after completing pesticide application.

To protect fish and wildlife, do not contaminate lakes, streams,

or ponds with pesticide. Do not clean spraying equipment or dump

excess spray material near such water.

To minimize losses of honey bees and other pollinating insects,

make pesticide applications, when possible, during hours when the

insects are not visiting the plants. Avoid drift of pesticide sprays

to nearby crops or livestock. Avoid drift of pesticides into bee yards.

Empty containers are particularly hazardous. Burn empty bags

and cardboard containers in the open or bury them. Crush and bury

bottles or cans.

Credit for preparation of the basic information in this handbook on

culture of peaches and compilation of the initial draft of the handbook

is due A. Leon Havis, formerly horticulturist. Crops Research Division, Agricultural Research Service. Dr. Havis died in 1962.

Mention of a proprietary product in this publication does not constitute

a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval by the Department to the exclusion of other products that may also be suitable.
PEACH PRODUCTION EAST OF

THE ROCKY MOUNTAINS

Agriculture Handbook No. 280

Agricultural Research Service

US. DEPARTMENT OF AGRICULTURE
CONTENTS

Fag9

History of the peach 1

Geographic distribution of

peaches in the United

States 2

Selecting orchard sites 4

Selecting varieties 6

Standard commercial varieties -— 7

Special-pm^pose varieties. _ 10

Promising new varieties, _ 12

Propagating and selecting

rootstocks 13

Planting the orchard 15

Age and size of trees 15

Time to plant 15

Planting patterns and

spacings 16

Preparing the site 17

Setting out the trees 18

Replanting the orchard___ 18

Training and pruning 18

The young tree 19

The bearing tree 21

Time of pruning 28

Pruning in relation to fruit

thinning 29

Pruning in relation to fertilizmg 29

Pruning tools and equipment 30

Soil management 30

The young orchard 31

The bearing orchard 33

Fertilizers 35

Nitrogen 35

Potassium, phosphorus,

magnesium, and calcium 37

Zinc, boron, and manganese 39

Irrigation 39

Page

Thinning the fruit. 40

Thinnmg according to variety 40

Amount to thin 41

Methods of thinning 42

Low-temperatiu-e injury 42

Injury to buds 42

Injury to twigs, branches,

and trunks 44

Injury to roots 44

Harvesting, transporting,

and storing fruit 44

Diseases caused by fungi and

bacteria 50

Brown rot 50

Scab__ 52

Bacterial spot 53

Leaf cm*l 55

Rust 56

Constriction 56

Crown gall 57

Powdery mildew 57

Fungus root rots 57

Dieback 57

Diseases caused by viruses._ 58

Peach yellows 58

Little peach 61

Red suture 61

X-disease 62

Phony disease 63

Peach rosette 64

Peach mosaic 64

Rosette mosaic, ring spot,

necrotic leaf spot, line

pattern, and asteroid

spot

Peach insects 67

Plum curculio 67

Peach tree borer 67

Lesser peach tree borer. __ 68

San Jose scale 68

Oriental fruit moth 68

Sucking bugs 68

66

This handbook contains the type of information that formerly appeared

in Farmers' Bulletin No. 2021, "Peach Growing East of the Rocky

Mountains."

Washington, D.C. Issued April 1965

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

Washington, D.C, 20402 — Price 35 cents.
PEACH PRODUCTION EAST OF THE ROCKY MOUNTAINS

By H, W. FoQle," H. L. Keil^ W. H. Redit,' L. 0. Cochran,'' and H. Baker ^

HISTORY OF THE PEACH

The peach {Pnimis pérsica (L)

Batsch) originated in China and

was taken from there into Persia,

Greece, Italy, and other temperate

areas of Europe.

Probably the earliest introduction of peaches into the Western

Hemisphere was by the Spaniards,

who brought them to Mexico. In

1565, Spanish settlers brought

peaches to St. Augustine, Fla. The

early English and French settlers

also brought peach seeds with them

to the Eastern United States.

Later, Indians planted peach seeds

over a wide area.

Until about 1910, most peach varieties originated as chance seedlings. The first peaches grown in

this country were probably white

fleshed. They were later crossed

with yellow-fleshed peaches brought

from Mexico. All commercial varieties now grown in the United

States originated in this country.

The most important new varieties

originated from controlled crosses

made at State or Federal experiment stations or by private fruit

breeders.

For 200 years after their introduction into the United States,

seedling peaches were grown mostly

for brandy, for fresh fruit for the

home, or for hog feed. Almost

every farm and plantation in the

Middle Atlantic States had a peach

orchard. No spraying was done,

but the trees evidently produced

well. By aTbout 1800, several good

varieties had been selected from

seedlings and propagated by budding;. By 1850, more than 400 varieties were listed by nurseries in

this country.

From 1800 to 1850, commercial

peach production expanded rapidly. Peaches were transported by

rail, by boat, and by wagon to supply the demand for fresh peaches

in the cities. Peach production

mostly was for family use, although

commercial orchards were being developed near Richmond, Norfolk,

and Baltimore. Peach seedlings, as

well as budded varieties for home

use, were carried west by settlers

during the 19th century.

Commercial shipment of peaches

to terminal markets developed

gradually from 1870 to 1900. Selection of the Elberta and Belle

varieties and development of the

refrigerated rail car were important

in market expansion. Commercial

peach growing increased in Virginia, Maryland, Delaware, New

Jersey, and southeastern New York.

Throughout the 19th century, disease and insect problems multiplied

as commercial peach production in

America expanded. Peach yellows

and brown rot diseases and insect

borers became increasingly destructive. The yellows virus, which became serious in the Philadelphia

area about 1800, caused greater loss

of peach trees in Northeastern

2 Crops Research Division.

^ Market Quality Research Division.

Entomology Research Division ; now retired.
United States than did any other

trouble. The most serious losses

occurred between 1850 and 1900 in

New Jersey, in Delaware, and on

the Eastern Shore of Maryland.

Thousands of trees and many large

plantings were completely destroyed. Serious losses also occurred as far west as Ohio and

Michigan, but the virus caused no

damage to the developing peach

areas in the Southeast. In 1892, the

San Jose scale insect appeared in

Virginia and quickly spread to other

fruit areas. Spring frosts were a

major hazard to the growing commercial peach industry. The appearance of San Jose scale in 1892

m Virginia and its rapid spread to

other fruit areas led to the adoption

of spraying as an orchard practice.

A realization of the value of spraying for other insects and diseases

soon developed.

Most of the early commercial orchards were clean cultivated. Pruning methods were variable and

sometimes severe. Before the use

of nitrogenous fertilizers in orchards, clean cultivating and heavy

pruning were practiced in some locations to stimulate vigorous annual

growth. Peach varieties selected

between 1850 and 1900 that are still

grown commercially include Elberta. Belle, and Champion, and, to

a lesser extent, Carman and Hiley.

From 1900 to 1920, the peach industry in the United States expanded, especially in Georgia,

South Carolina, Arkansas, Texas,

and California. Production

reached its peak economically in

the United States during this period. Then fruit prices suddenly

fell, and thousands of acres of peach

trees were abandoned.

The economic recovery was slow

and irregular, even for the most efficient growers and at the best cultural locations. World War II

brought high peach prices, but it

also brought shortages of labor,

equipment, and supplies. In the

postwar period, the high cost of

labor, equipment, sprays, fertilizers,

and land made profits uncertain in

most areas. Although high production per acre of high-quality

fruit over a long period of years has

usually been profitable, such hazards as spring frost, winter injury,

insects, diseases, and hail continued

to plague fruit growers.

Since 1890, the number of peach

trees in the United States has fluctuated but has generally declined

(fig. 1 ). However, during the same

period production has increased.

GEOGRAPHIC DISTRIBUTION OF PEACHES IN THE UNITED STATES

Commercial culture of peaches is

more widespread in the United

States than that of any other tree

fruit, even though in many areas

annual production is uncertain and

variable. Peaches are produced

commercially over a wide area that

begins in New Jersey, extends into

the South Atlantic States, and

reaches into central Texas. Peachproducing sections within this area

include parts of the Piedmont and

the Coastal Plain. The Piedmont

extends from south-central Georgia

through the Carolinas and Virginia

and into Maryland, and includes

parts of the Coastal Plam in the

Carolinas, Maryland's Eastern

Shore, Delaware, and New Jersey.

Many large plantings border the

Great Lakes in western New York,

northern Ohio, and southwestern

Michigan.

In the Far West, climate and soil

in the San Joaquin and Sacramento

River Valleys of California are exceptionally favorable to commercial peach production. This fact

has stimulated heavy planting.

Peaches are also grown under irrigation in western Colorado, northem Utah, southern Idaho, and cen-,

tral Washington (fig. 2).
TREES (Millions)

40 80

BUSHELS (Millions)

40 80

FOR 1954, DOES NOT INCLUDE DATA FOR FARMS WITH LESS THAN 20 TREES. ^BEARING AND NONBEARINC

TREES NOT REPORTED SEPARATELY. ^DATA NOT AVAILABLE FOR NOHBEARING TREES.

^^^B 0^ bearing age V/////Á Not of bearing age

FIGURE 1.—Number oF peach trees in the United States and annual production, 1889-1963.

Co ^' ^.°^°*'°" °^ principal peach tree plantings in the United States in 1959. Greatest

nccntrations of plantings are in California, South Carolina, Georgia, and Michigan.
Large-scale peach production in

a given locality may mean that

peaches gi^ow especially well there,

or it may mean only that they grow

better there than do other crops.

Some areas in this country are not

suitable for peach growing. Many

States in the North and several

States in the Great Plains and the

Rocky Mountain region have such

cold winters that only the hardiest

peach varieties survive, and even

those varieties often fail to bear

fniit. In extreme south Georgia,

in Florida, and in the southern parts

of tlie States bordering the Gulf of

Mexico, none of the leading peach

varieties produces well enough to be

grown commercially because the

winters are too warm. Although

peach trees do not thrive where

winter weather is severe, their buds

do require some winter chilling. If

a peach tree does not have enough

chilling during the winter, its shoot

growth and blossoming are delajyed

the next spring and, after particularly mild winters, fail to develop

at all. Most leading peach varieties

require chilling below 45° F. for

600 to 1,400 hours.

Flowerbuds of most varieties require slightly less chilling than do

leafbuds. Flowerbuds of peaches

are formed only in axils of leaves,

and they vary from none to three.

Usually at least one leafbud occurs

in the axil of each leaf, and the

terminal bud on the twig is always

a leafl^ud. Leafbuds and flowerbuds are formed during the summer,

develop slowly during the winter,

and develop rapidly in warm weather after the required chilling time.

For the 10-year period 1951-60,

annual peach production in the

LTnited States averaged 65,650,000

l)ushels. From 1944 to 1948, commercial peach production reached

its highest average for a 5-year

period—75,442,000 bushels. The

1959-63 crops also averaged more

than 75 million bushels. Production from 1956 to 1963 averaged 72

million bushels annually. The

States having the highest production and their approximate average

yields, for this 8-year period were:

California—40 million bushels (including 28 million clingstones and

12 million freestones) ; South Carolina—5 million bushels; Georgia—4

million bushels; Michigan—§ million bushels; Pennsylvania—2,700,-

000 bushels; New Jersey—2,300,000

bushels; Washington—1,750,000

bushels; Arkansas, Virginia, Colorado, and Nortli Carolina—about

1,500,000 bushels each. Improved

peach varieties and improved methods of canning, freezing, and transporting are increasing the potential consumption of high-quality

peaches in the United States.

SELECTING ORCHARD SITES

In selecting a peach orchard site,

not only the elevation, topography,

and slope of the land but also the

depth, moisture-holding capacity,

and other physical features of the

soil should be carefully considered.

Satisfactory sites are found on both

hilly and level land.

In the peach-producing areas of

the South Atlantic and South Central States, few sites have winter

temperatures low enough to injure

dormant flowerbuds. But on many

sites, fruit crops may be lost because

of frost at blossoming time. In the

New England, Middle Atlantic, and

East Central States, peach orchard

sites should be selected that ofier

protection from occasional spring

frosts and from severe winter cold.

Orchards on sites having poor air

drainage are most likely to suffer

from winter cold and spring frostOn clear, cold, still nights, heat is

lost from the earth by radiation.

Warm air rises and is replaced by a

layer of cold air near the ground.

At higher levels, the corresponding

layer of air is warmer. A difference

of only a few feet in elevation may
mean a difference of one to several

degrees in temperature during the

critical period of a frosty night. If

air movement is slowed down hy a

ridge or by trees, cold air may accumulate behind them in pockets on

the slopes. In most localities, therefore, the site for a peach orchard

should be on land elevated above

adjacent land and free of obstructions to air movement, so that cold

air can settle to the lower levels.

Gently sloping or level land may be

satisfactory where the climate is

mild or where a nearby body of

water affords natural protection

from cold.

An orchard on the leeward side

of a large body of water is often

protectecl from spring frost because

the temperature of the water has a

modifying effect that prevents sudden, severe drops in air temperature. Ochards planted near bodies

of water are found on strips of

land 10 to 15 miles wide along the

eastern shore of Lake Michigan and

the southern shore of Lake Ontario.

Masses of cold air blowing over

these lakes are warmed by the water.

Also, air movement across the cold

water in early spring tends to prevent sudden rises in air temperature

that would cause peach blossoms to

open too early and be injured later

by low temperatures.

Although a peach orchard site

usually should be at an elevation

higher than that of the adjoining

land, a hilltop location has a disadvantage if it exposes trees to cold,

drying winds during winter.

Peach trees planted on sites exposed

to strong, prevailing winds not only

niay be damaged by cold but also

^ay be permanently dislodged.

This is especially true in young

orchards where high winds accompany heavy rains that have softened

the soil.

Before selecting his peach orchard site, an orchardist should determine the lowest winter and

spring temperatures for that location. This he can do by placing, at

different elevations on the site,

thermometers that will automatically record minimum daily air

temperature.

Peach trees grow well on a

variety of soils, ranging from coarse

sand or shale to fine-textured clay

loams. NeA^ertheless, they ^ill not

grow so well on heavy soils as will

apple and pear trees. Soils poorly

drained or poorly aerated are not

satisfactory for peach trees. During their growing season, peach

trees are very likely to be injured if

the orchard water table is temporarily raised bj^ hea\^ rains or by

accumulation of irrigation water.

^^Hiere excess Avater does not pass

through the soil quickly but accumulates and fills the pore spaces between soil particles, it shuts off the

oxygen supply to the tree roots,

which die. Tree injury caused by

excess water is often indicated by

yellowing of the foilage in early

summer, especially where soil becomes saturated with water soon

after peach trees start growing in

the spring. Winter injury to peach

trees in water-saturated soil, as well

as tnmk and root disease injury, is

frequently severe and may result in

early death of the trees. The best

peach orchards are on well-drained

sandy or gravelly loam soils.

Although the lighter soils (such

as the coarse sands, gravels, and

shales) usually have better aeration

and drainage, they may not drain

well if underlaid by impervdous

clay, hardpan, or rock. Too much

water may accumulate near the root

zone of the trees after heavy summer and fall rains. The low waterretention characteristic of lighter

soils is not always an advantage in

localities where simimer droughts

occur and irrigation is not practiced. For satisfactory growth and

fruit production, peach trees require a water supply that is readily

available.

An ideal soil for peaches is one
having about 8 feet of sandy loam

luiderlaid by a clay loam capable of

retaining and storing most of the

rainfall.

Hillside situes, besides having

good air drainage, often have satisfactory surface drainage of excess

rainwater. On some hillsides the

soil is only 3 or 4 feet deep. Trees

will grow in shallow soil in the

humid regions where the rainfall

averages 4 or 5 inches a month during the growing season, or where

the trees are irrigated. In regions

where rainfall may be deficient for

periods of from 4 to 6 weeks in the

summer or where there is no irrigation, shallow coarse soils cannot

store enough water to meet the

needs of the trees.

Since selecting a peach site is so

important, prospective growers

should consult their local experiment station and extension specialists. In general, the following factors should be considered:

1. Spring frost protection on

higher locations and from

nearby lakes.

2. Protection from wind and low

temperatures by planting on

least exposed locations.

3. Soil-water drainage in deep

loam soils.

4. Soil-moisture capacity desired

for best fruit development.

SELECTING VARIETIES

Since 1940, many new peach varieties have been developed. In this

handbook, only the leading commercial and certain outstanding,

new special-purpose varieties are

described (table 1). For specific

varietal recommendations, consult

your local experiment stations and

cooperative extension personnel.

Local environment and marketing

outlets determine the varieties

grown. For example, if peaches

are grown for a nearby market,

high-quality varieties that ripen in

sequence during the season rather

than varieties especially suited for

shipping to distant markets should

be grown. In many sections, the

hardiness of flowerbuds is important in selecting a variety for a

specific climate. Dependable annual production is necessary for successful peach growing.

Basecl on flesh texture, peach varieties are classified as either melting (such as Elberta), or nonmelting (such as Ambergem). Melting

varieties are grown for dessert and

for processing. Nonmelting varieties are grown almost entirely for

processing. Most early-ripening

varieties with melting flesh such as

Dixired are freestones genetically

but the flesh adheres tightly until

the fruit is overripe. Most lateripening varieties, however, are entirely freestones. Varieties with

nonmelting flesh are all clingstones.

Peaches ripen over a period of

about 3 months. For convenience

in describing varieties, the ripening

period has been arbitrarily classified

into four general seasons of ripening:

1. Very early—more than 5 weeks

earlier than Elberta and generally

referred to as the Dixired season.

2. Early—from 3 to 5 weeks earlier than Elberta and referred to as

the Redhaven season.

3. Midseason—less than 3 weeks

earlier than Elberta. This season

is usually divided into the Halehaven or July Elberta season (or varieties about 2 weeks before Elberta), and the Elberta season.

4. Late—all varieties ripening

after Elberta. Tliis is usually

called the Rio Oso Gem season.

Comparative ratings of economically important varietal characteristics are given in table 1. The varietal descriptions that follow give

the ripening period and certain outstanding strong or weak characteristics of (1) standard commercial.
varieties, (2) special-purpose varieties, and (3) promising new varieties.

Elberta is still the leading peach

variety, although it has become less

popular in recent years. Varieties

with high quality and attractiveness, such as M. A. Blake and Redskin, are replacing Elberta for the

Elberta season of ripening. Likewise, Golden Jubilee and Halehaven, which were very popular a

few years ago, are being replaced

in their ripening season by such

varieties as Redhaven, Sunhigh,

Richhaven, and Redglobe. Firmness and attractiveness are the chief

merits of these newer varieties.

Standord Commercial Varieties

The following peach varieties,

listed in approxmiate order of ripening, are suitable for general commercial production east of the

Rocky Mountains :

Dixired.—Very early, ripening 5

to 6 weeks before Elberta. Fruits

medium sized. Blush bright red.

Flesh yellow, medium firm; melting, with strong tendency to cling.

Promising for very early shipping

or for local marketing where earline>ss is of prime importance and

where freeness of the pit is not

required. Considerable acreage

planted in the Southeast.

Redhaven,—Early, ripening 4 to

5 weeks before Elberta. Fruits require early and heavy thinning to

develop best size. Skin bright red,

attractive; flesh yellow. Usually

freestone when ripe. Flowerbuds

moderately hardy. Variety becoming more and more popular because

of fruit's firmness, attractiveness,

and earliness. Excellent for canning

and freezing.

Golden Jubilee,—Early, ripening

3 to 4 weeks before Elberta. Fruits

medium sized, attractive red blush

and yellow undercolor. Shape compressed, especially in southern

areas. Flesh yellow and medium

soft; freestone. Flowerbuds fairly

hardy. Fruits should be thinned

early and well. Valuable where

hardiness is important and market

is nearby. Not firm enough for distance shipping.

Triogem,—Early, ripening about

3 weeks before Elberta. Fruits medium sized, with attractive skin

color. Flesh yellow, fine textured,

and firm; usually freestone. Flow-

. erbuds tender to IOAV temperatures.

Fruit may be small unless thinned

well and early.

Sunhigh.—Early m i d s e a s o n.

Fruits large. Skin attractive, light,

solid red. Flesh attractive, fine texture, yellow, firm ; usually freestone.

Buds fairly hardy to low winter

temperature, but apparently sensitive to low temperature in early

spring. Susceptible to bacterial

spot. Relatively short chilling period required.

July Elherta.—Midseason, ripening about 2 weeks before Elberta.

Fruits large, round. Flesh yellow

and fairly firm; freestone. Trees

productive. Chilling period short.

One of the best commercial varieties for its season in several peach

areas.

Hatehaven.—^Midseason, ripening 2 weeks before Elberta. Fruits

large, round. Skin color sometimes

dull. Flesh yellow and fairly firm

for season ; freestone. Flowerbuds

fairly hardy. Trees vigorous and

productive. Fruit set often heavy,

making detailed thinning necessary.

Belle {Belle of Georgia) ,—M\àseason. Flesh white, or high quality ; usually freestone. Skin sometimes lacks color. Flowerbuds

hardy. Usually preferred as a

white variety ripening just before

Elberta, but not planted extensively.

Sullivan's Early Elberta.—Miaseason, ripening 1 week before Elberta. Similar to Elberta in all respects except earlier ripening. One

of the most extensively planted

varieties several years ago, especially in the Southeast.

'757-340 O—$5-
* TABLE 1.—Characteristics of some peach varieties for use east of the Rocky Mountains^ listed in approximate order of

ripening

[Numerical ratings of quality characteristics range from 1 to 10; the higher values indicate more desirable characteristics]

Ripening season and

variety

Approximate

ripening

date, in days

before or

after

Elberta i

Color of

flesh

Fruit

size

Stone

freeness

Attractiveness

Flesh

firmness

Dessert

quality

Canning

quality

Bacterial

spot

resistance

Chilling

requirements

(hours below 45° F.)

Principal

value 2

Very early:

Redwin _ _ _ -63

-63

-61

-60

-58

-50

-49

-48

-46

-45

-44

-42

-42

-42

-40

-38

-38

-35

-33

-33

-32

-30

-30

— 27

— 25

— 25

White

Yellow—.

White..-..

Yellow-.-.

White

Yellow...-

Yellow--..

Yellow.-.

Yellow..-.

Yellow—-

Yellow..-.

Yellow.—

Yellow.-..

Yellow....

White

Yellow.—

Yellow.-.

Yellow.—

Yellow.—

Yellow.—

Yellow.—

YellowsYellow..-

White

YellowsYellow-...

5

5

3

4

3

6

5

5

6

6

6

6

6

6

7

7

7

7

7

8

7

7

8

8

8

8

4

4

3

3

3

5

5

5

4

5

5

4

4

4

6

6

6

6

7

8

7

7

7

8

8

6

6

6

7

6

6

8

8

7

8

7

8

7

7

8

7

6

7

7

I

7

8

7

8

7

7

4

4

3

3

3

6

6

5

6

6

7

6

6

6

6

7

7

7

8

8

7

8

8

6

6

8

6

6

6

6

5

7

7

6

7

5

7

7

7

8

8

7

8

8

9

8

9

8

8

9

8

7

4

4

3

3

3

4

4

4

4

3

800

800

650

600

1,200

850

HLC

Marcus 5

6

HLC

Springtime HLC

Earligold HLC

Mayflower 7

7

HLC

Earlired _ _ __ HLC

Collins _ HLC

Sunrise 8

7

5

900

950

700

HL

Cardinal _ — LC

June Gold HL

Early Redhaven

Dixired

LC

4

4

4

4

5

5

6

7

7

7

7

7

7

8

7

8

6

7

8

6

8

6

6

4

7

8

6

9

8

7

1,000

650

750

900

LC

Maveold _ ._. LC

Redcap _ _ LC

Erly-Red-Fre HL

Merrill Gemfree LC

Sunhaven 900

800

750

850

850

950

850

950

850

HLC

Early:

Starking Delicious

Coronet - _- --

HL

HLC

Jerseyland- LC

Dixieem _ LC

Redhaven — - HLC

Regina LC

Raritan Rose

Golden Jubilee.

HL

HL

Goldgem L
Ranger.

Suwanee

Washington

Keystone

Triogem

Midseason:

Fairhaven

Sunhigh

Richhaven

July Elberta

Ambergem

Southland

Halehaven

Redglobe

Loring

Veteran

Belle

Suncrest

Sullivan's Early

Elberta.

Allred Elberta

M. A. Blake__.

Early Elberta

Redskin

H. H. Brilliant

Elberta

Dixiland

J. H. Haie

Jefferson

Late:

Shippers Late Red,

Afterglow

Rio Oso Gem

Kimbo

Laterose

Constitution

Autumn

Salwey

Krummel__

— 25 — 25 — 24 — 22 — 22

-19

-17

-16

-15

-14

-14

-14

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1 At Beltsville, Md.»H=home;L= local market;C= commercial market.
ETberta,—Fruits large, with red

blush. Flesh yellow, finii, of fair to

good quality; freestone. Flowerbuds sensitive to low temperature.

Trees productive. By far the leading peach variety in the United

States. Its popularity with growers is due to the large size, firamess,

attractiveness, and shipping quality

of its fruit ; the vigor of the trees ;

and its suitability to many soil and

climatic conditions. Although Elberta is still considered the principal commercial midseason variety, midseason varieties superior to

it in quality, hardiness, and skin

color are being planted in many

orchards.

Rio Oso Gem.—Late, ripening

nearly a week after Elberta. Fruits

large, of good quality. Medium to

bright blush. Flesh yellow, fími;

freestone. Flowerbuds sensitive to

low temperature. Trees rather

weak, moderately productive. Susceptible to bacterial spot. Popular

with many growers because of size,

firmness, attractiveness of fruit,

and time of ripening.

Special-Purpose Varieties

The following peach varieties are

suitable for certain localities for special purposes, or for extending the

ripening season. These varieties are

listed in the approximate order of

ripening:

May-ßoioer,—Very early, ripening

about 8 weeks before Elberta.

Fruits small. Skin mostly red.

Flesh white, soft, juicy; clingstone.

Yields usually IOAV. Early ripening

the only merit.

Hilcmd.—Very early, ripening

about 6 weeks before Elberta, about

2 weeks before Redhaven, and a few

days before Redcap. Fruits medium to large. Flesh yellow, medium

firm, melting ; clingstone. For very

early shipping in present southern

commercial peach areas. Chilling

requirement low.

Cardinal.—Very early, ripening

about same time as Hiland. Fruits

medium sized. Skm bright and attractive. Flesh yellow, firm, melting; clingstone. For very early

shipment in areas where there is

enough winter chilling for varieties

such as Elberta.

Redcap.—Very early, ripening a

few days later than Hiland and

same time as Dixired. Fruits medium sized. Skin bright red. Fleslv

yellow, firm, melting; clin^tone.

Used for early shippmg variety in

southern areas. Chilling requirement fairly low.

Maygold.—Very early, ripening

same time as Redcap and Dixired.

Fruits medium sized, and well colored. Flesh yellow, medium firm,

melting ; clingstone. Used for early

shipping in southernmost commercial peach-growing areas. Will

grow slightly farther south than

either Hiland or Redcap.

Erly-Red-Fre.—Very early, ripening 5 to 6 weeks before Elberta.

Fruits large for early season. Skin

partly red. Flesh white; often

freestone when fully ripe. Trees

productive and winter hardy.

Flowerbuds hardy to low winter

temperatures.

Prairie Dawn.—Very early, ripening 5 weeks before Elberta, or

about 1 week before Redhaven.

Fruits medium to large. Skin

partly red. Flesh yellow, medium

finn; usually freestone when ripe.

Resistant to bacterial leaf spot.

Flowerbuds hardy to low winter

temperatures.

Coronet.—Early, ripening 4 to 5

weeks before Elberta. Fruits medium sized. Skin mostly red and very

bright. Flesh yellow, finn; usually

freestone. Low chilling requirement similar to that of Redcap.

Early ñower development sometimes damaged by spring frost. An

attractive shipping peach, often

used to follow Redcap harvest m

the South.

Jerseyland.—E?iñy^ ripening 4 to

5 weeks before Elberta. Fruits

10
medium to large. Skin often solid

red. Flesh yellow, firm; usually

freestone. Dependable production

over wide area. Susceptible to bacterial spot disease.

Dixigem,—Early, ripening 4 to 5

weeks before Elberta and about

1 week before Golden Jubilee.

Fruits medium sized. Bright yellow, with light-to-medium red over

about half the skin surface. Flesh

yellow, firm, fine textured; usually

freestone when ripe.

Raritan Rose.—Early, ripening 4

weeks before Elberta. Skin a

bright, attractive red. Flesh white,

fine textured; freestone. Hardy

and productive. Has special merit

for local sale wdiere an early w^hite

variety is desired.

Ranger,—Early, ripening same

time as Golden Jubilee, or 3 to 4

weeks before Elberta. Fruits medium to large. Flesh yellow, firm ;

freestone. Dependable producer

over wide area. Blooms late and

requires considerable chilling. Ee-

: sistant to bacterial spot disease.

Redglobe,—Early midseason, ripening same time as July Elberta.

Fruits medium to large and attractive. Flesh yellow, especially firm

and fine textured; freestone. Dependable producer. Good shipping

peach.

Southland,—Early midseason,

ripening 2 to 3 weeks before Elberta, or with July Elberta. Fruits

medium to large, round, firm, and

attractive. Skin has medium blush.

Chilling requirement low^. Has

been planted for a shipping variety

m Southeastern United States.

Ambergem.—Esirlj midseason.

Fruits medium sized, round. Flesh

yellow, nonmelting, firm, fine textured; clingstone. Flow^erbuds

hardy to low winter temperature—

slightly more hardy than those of

Halehaven. Trees productive,

usually planted for canning purposes. Preferable to western clingstone varieties for planting east of

ßocky Mountains.

Champion,—Midseason. Flesh

white, fine textured, and of excellent

dessert- quality; usually freestone.

Fruits lack firmness. Flowerbuds

very hardy to low temperature.

Susceptible to brown rot.

Redskhi,—Midseason, ripening

about same time as Elberta. Fruits

large, round. Skin attractive and

almost solid bright red. Flesh yellow, free, firm. Popular variety

planted to replace Elberta in many

areas because of its attractiveness

and quality. Good for freezing

and canning.

</. H, Hale,—Midseason, ripening

same time as Elberta. Fruits large.

Skin an attractive red. Flesh yellow, firm, fine textured, and of high

dessert quality ; freestone. Flowerbuds sensitive to low temperature.

Cross-pollination necessary to fruit

setting. Trees lacking m vigor,

often not productive, and very susceptible to bacterial spot. Often

unprofitable to grow m Eastern

States, although fruit may bring a

premium because of high quality.

AftergJoio,—Late, ripening nearly 1 week after Elberta. Fruits

large. Skin medium to light blush.

Flesh yellow and firm. Flowerbuds

fairly sensitive to low temperature.

Trees moderately vigorous and productive. Although usually not so

highly colored as Eio Oso Gem,

Afterglow is sometimes preferred to

it because of greater tree vigor and

slightly greater flowerbud hardiness.

Laterose,—Late, ripening about

10 days after Elberta. Fruits medium to large. Skin attractive red

blush. Flesh white, medium firm,

and fine textured ; freestone. Trees

vigorous and productive. A good

white variety to follow the Elberta

season.

Lizzie,—^Late, ripening about 2

weeks after Elberta. Fruits medium sized and lacking in skin color.

Flesh medium firm, yellow, of fairto-good quality. Flowerbuds sensitive to low temperature. Greatest

n
disadvantage, lack of skin color.

Limited plantings.

Autumn.—Very late, ripening 3

to 4 weeks after Elberta. Fruits

medium to large. Skin color often

slightly dull. Flesh yellow, firm;

freestone. Often lacks attractiveness and good flavor but is fairly

satisfactory for a late peach.

Promising New Varieties

Many new peach varieties are

promising but have not been tested

thoroughly enough to be described

accurately. Descriptions of some of

the most promising new varieties

follow in the approximate order of

ripening.

Redwin.—Very early. Evidently

a sport of Erly-Red-Fre, ripening

at least 2 to 3 weeks earlier. Flesh

white; semifreestone when fully

ripe.

Marcus.—Very early, ripening a

few days before Mayflower. Attractive yellow and red skin. Yellow flesh. Fruit medium sized.

Springtiine,—Very early, ripening 2 to 3 days before Mayflower.

Fruits small to medium sized. Skin

usually almost solid red. Flesh

white and juicy.

Dœione.—Very early. Attractive,

yellow flesh.

Earlired,—Very early, ripening a

few days before Cardinal and about

8 days before Sunhaven. Attractive, firm, with good flavor. Fruits

medium sized and semifreestone.

GolliThs,—Very early, ripening

just before Cardinal. Attractive

skin color and relatively firm flesh.

Fruits medium sized and semifreestone. Susceptible to bacterial spot

disease.

Early Redhaven.—Very early,

ripening about with Dixired. Attractive undercolor. Fruits firm

and semifreestone.

Sunhaven,—Very early, ripening

with Dixired or about 10 days before Redhaven. Fruits mediimi

sized, round, but rough in more

southern areas. Skin attractive,

bright red. Flesh yellow, firm;

semifreestone when ripe.

Goldenred.—Early, ripening several days after start, of Redhaven

season. Attractive yellow ground

color. Fruits medium to large,

round, and of good quality. Flesh

yellow, medium firm; freestone.

Washington,—E a r 1 y, ripening

with Golden Jubilee. Fruits large,

round, attractive. Flesh yellow,

firm, and of good quality ; freestone.

Early tests indicate frost hardiness.

Keystone,—Early, ripening with

Golden Jubilee-. Fruits medium to

large sized, round. Skin attractive,

red and yellow. Flesh yellow, firm ;

freestone. Now being tested commercially to replace early white

varieties with a yellow peach.

Goldgem,—Early, ripening in

Golden Jubilee season. Flesh yellow, medium firm; freestone.

Suumnee.—Early, ripening between Golden Jubilee and Keystone

seasons. Flesh yellow, firm, freestone. Low chilling requirement.

Light pubescence.

Richhaven,—Midseason, ripening

with Sunhigh and July Elberta, or

often 2 days before Halehaven.

Fruits medium sized to large and

round. Skin color similar to Halehaven except brighter red and yellow. Flesh yellow, firm ; freestone.

Summerqueen,—Midseason, ripening about same time as Sunhigh

and July Elberta. Fruits medium

sized to large. Flesh yellow, firm;

freestone. Requires cross-pollination.

Loring. — Midseason, ripening

during latter part of Halehaven

season and extending that season.

Fruits medium sized to large and

round. Skin attractive red with

yellow undercolor. Flesh yellow,

firm; freestone. Resistant to bacterial spot disease. Most promising

variety to extend the July ElbertaHalehaven season.

Suncrest,—Midseason, ripening

with Sullivan Elberta. Fruits

12
large, round. Skin bright red if

trees are very vigorous; otherwise

red blush dull sometimes in Southeastern United States. Flesh yellow, firm; freestone. Very susceptible to bact-erial spot.

M. A, Bhke.—Midseason, usually

ripens a few days before Elberta

but after Sullivan Elberta. Fruits

medium to large, round. Skin attractive, almost entirely red. Flesh

yellow, firm, and of good quality;

freestone.

Dixiland,—Midseason, ripening

with or just before Elberta. Fruits

large, ovate, freestone. Light pubescence. Low chilling requirement. Eesistant to bacterial spot.

Jejferson,—Midseason, ripening

same time as or just after Elberta.

Fruits large, round. Skin attractive, bright yellow and red. Flesh

yellow, very firm, and of good quality; freestone. Reported to withstand spring frosts well.

PROPAGATING AND SELECTING ROOTSTOCKS

Nurserymen offer a choice of sizes

and grades of the popular and

promising new varieties, guaranteed

to grow and to be true to variety.

Most peach growers, therefore, purchase their trees directly from reliable nurseries rather than propagate

their own trees. Nevertheless, some

peach growers may want to propagate their own trees for some special

purpose such as reproducing a variety prized for jam or canning but

not obtainable commercially.

A peach generally cannot be reproduced true to variety from seeds.

Plants grown from seeds of a given

peach tree may differ considerably

in tree and fruit characteristics

from the parent tree, even though

there has been no cross-pollination.

Seedlings of some varieties are more

uniform than those of others. In

rehable nurseries, the main purpose

of germinating peach seeds is to

grow young trees, called understocks, on which to bud or graft dp

sired varieties.

Peaches may be propagated on

lïiost fruit trees in the Prunus

genus, such as peach, plum, apricot,

or almond. Compatibility and top

growth vary among varieties of

these species, however. In general,

buds of desired varieties are compatible when budded to seedlings of

the common peach varieties. Elberta and Halehaven peaches budded

to seedlings grown from seeds of

about 50 peach varieties showed

little difference in tree size and

yield.

For general rootstock purposes,

peach seeds should be available in

large quantity, should be economical, and should germinate well in

the nursery. Previously, most seeds

used for peach understocks came

from seedling peach trees in the

Carolinas, Kentuck)^, Tennessee,

and elsewhere in the South. The

supply of reliable seeds from these

sources has dwindled, and understocks are now largely from seeds of

Lovell, a variety used in California

for drying. Lovell seeds make satisfactory understocks except where

nematodes are numerous. The future supply of Lovell seeds is questionable because of reduced planting of this variety. Seeds of Elberta are available in large quantities, from canneries, but germination varies from year to year. Satisfactory germination of seeds of

Elberta and other midseason and

late varieties is usually obtained

when the seeds are kept moist and

given a longer chilling period than

Lovell seeds. Trees on these rootstocks usually are very satisfactory.

Seeds from red-leaved varieties are

used by a few nurseries because this

practice permits easy spotting of

red-leaved trees developing from the

rootstock seedling rather than the

scion variety. Rogueing out the

13
red-leaved trees eliminates this

source of error in producing true-tovariety trees.

Nematode injury to peach roots in

some areas has resulted in importing, selecting, and breeding for neniatode-resistant rootstock varieties

(fig. 3). The Shalil variety from

India and Yunnan from China gave

resistance to the arrita nematode.

The S-37 rootstock in addition gave

slight resistance to the jnvanica species. Okinawa gave high resistance

to both nematodes but lacked vigor.

Nemaguard, introduced by the Department in 1961, combined vigorous seedling growth with dual resistance and high germination.

Understocks are being bred and

tested for improved nematode resistance, higher seed yields, higher

percentage of gemiination, vigorous

top growth, and greater hardiness.

Peaches have been budded to

many varieties and types of plum,

apricot, and almond trees to test

such characters as nematode resistance, winter hardiness, dwarfing.

scion-stock compatibility, and tolerance to w^et and dry soils. Results

with some of the St. Julian or Damson plum varieties were encouraging

but were not consistent. In other

plum varieties, the bud onions usually were not ci>mpatible, or the

trees were weak, dwarfed, and short

lived for some other reason,

Peaches budded on the western sand

cherry {Prunus besseyi) are often :

sold as dwarf peach trees. They

usually grow about 6 feet high and

bear early, normal-sized fruit; but

they are short lived. Heavy annual

pruning of peaches grafted onto

peach rootstocks, together with little nitogen fertilization, will produce a more satisfactory semidwarf

peach tree.

Peach seeds should receive an afterripening treatment for about 3

months to insure high germination •

and normal seedling growth. The

length of dormancy depends on the

variety. The seeds should be stored

over winter in damp peat or sand,

or in a mixture of the two, at a teraFIGURE 3.—DiFfercnces in root-knot nematode resistance of peach stocks. Left, nemafoderesistant stock,- right, susceptible stock.

14
sperature of 35^ to 40° F. ^ This

treatment is called afterripening or

^stratification. Sometimes the seeds

areafterripened outdoors in the fall

liii moist sand. Some nurseries afterripen the seeds in underground

pits. It is not necessary that the

seeds freeze, but it is necessary that

1 they be kept copl and moist. Early

^'in the spring, after suflicient afterripening, the seeds are planted in

'thenursery or garden.

: Phxnting peach seeds in the field

'in the fall about 2 inches deep and

^^in rows about 4 feet apart is a more

common practice than is stratification. Seeds so planted germinate

Jhe following spring. Too much

moisture, which occurs Avhen the soil

is poorly drained, injures the seeds

and prevents high percentage of

.^^germination. Special precautions

!niust sometimes be taken to protect

the seeds from rodents.

Budding desired peach varieties

onto young seedlings is done during

the first year of seedling grow^th.

The time for peach budding in the

South is usually June ; in the North,

it is usually late July or August.

The shield, or T-budding, method

is used. A T-shaped cut is made

near the base of the seedling. A

shield-shaped section of the bark of

a tree of the desired variety containing one bud is inserted into the

cut. The bud is then bound firmly

into position with rubberbands,

strips of raffia, or string. In about

2 ^veeks, or as soon asJhe bud has

set, the strips or rubberbands are cut

to prevent girdling. A¥lien the inserted bud starts growing, the seedling is cut off just above it. This is

done soon after June budding and

again early the next spring after

late-summer budding. All growth

except that from the desired bud is

removed.

PLANTING THE ORCHARD

Age and Size of Trees

One-year-old n u rs e r y-grown

peach trees are usually the most

satisfactory to plant. A 1-year-old

tree is a tree that has had one complete season's growth in the nursery

after being budded. A tree that is

budded early the first summer, as

many are in the South, is dug at the

end of the same season and is commonly referred to as a June-budded

tree. June-budded trees are usually

smaller than most 1-year-old trees

ibut are satisfactory for planting,

¡especially in regions that have long

growing seasons. They may be

straight, unbranched whips, or they

may have a few branches. Oneyear-old nursery-grown trees are

usually well branched.

Nurserymen who propagate large

numbers of peach trees grade them

according to height in feet, or diameter in fractions of an inch.

Well-grown June-budded trees are

usually 2 to 3 feet tall and sometimes taller. For general-purpose

planting, the medium-sized (4- to

5-foot), 1-year-old tree or the largest June-budded tree is satisfactory.

Time To Plant

Well-hardened, dormant peach

trees may be transplanted from the

nursery to the orchard in late fall,

winter, or early spring. Generally,

in the Southeast and the Southwest,

the best time for transplanting the

trees is during late fall or early winter. In the Middle Atlantic and

Middle South Central States, the

best time is late fall ; and in the New

England and North Central States,

late winter or early spring.

Where below-zero teniperatures

occur, accompanied by high winds,

and where soil without a snow cover

freezes to ^ considerable depth, fallplanted trees may dry out considerably and be injured by cold.

Trees planted in late winter or early

spring should be set out as soon as

15

^57-340 O-^fi.^
the soil is dry enough to be worked,

so that new roots can become established while soil temperatures and

moisture are favorable. Trees

planted late in the spring, especially

large trees, may become desiccated

and have a high mortality. Leafbuds of the transplanted trees develop when temperatures become

warm. It is important, therefore,

that spring-planted trees be set out

3 or 4 weeks before the leafbuds

start growth.

If trees are transplanted late in

the spring, small- and mediumsized trees may have a lower rate of

mortality than large trees at the

end of the first season in the orchard. If large trees (5 to 7 feet)

are planted in the fall or late winter (at least a month before growth

starts), their mortality rate will be

no higher than that of smaller trees

planted at the same time. They

will grow more during their first

year m the orchard than will the

smaller trees.

If trees are received from the

nursery at an unsuitable time for

planting because of soil or weather

conditions, they should be placed in

cool storage or "heeled in" outdoors

to prevent drying out. '^Heeling

in" means laying the trees on the

side of a trench in a sloping position and covering their roots with

soil. If planting must be delayed,

the soil should be packed tightly

around the roots. If the trees are

to be planted shortly, they may be

protected sufficiently by wrapping

some material such as burlap, excelsior, or old straw around their

roots, thoroughly moistening this

cover with water, and shielding the

trees from wind and sun. Roots

must be kept moist and cool but not

allowed to freeze.

Pfanting Patterns and Spacings

Peach trees are usually set out in

some rectangular pattern to permit tillage and other cultural work

in any direction. Where the land is

level or slopes no more than 5 feet

in 100, a square pattern is commonly

used ; that is, the distance between

trees in the row is the same as the

distance between rows.

Contour planting and terracing:

to conserve soil and wat^r in peach;

orchards is good practice where thei

soil erodes easily. On steep slopesi

or irregular land, trees should be

contour planted. In contour planting, the trees are set about the same

distance apart witliin the row; but

each row follows a true contour line

or else a line sloping so little that

the soil drains but does not erode.

The distance between rows in a contour-planted orchard varies with

the degree of slope of the land. In

such an orchard, cultivation and

other operations are carried on only

along the rows—never up and down

the slope. By cultivating in one direction and working the soil toward

the trees, a contour ridge is built up

along each tree row.

The principal advantage of the

contour method of planting is that

soil erosion, which is often serious

in cultivated orchards planted on

the square system on sloping sites, is

reduced to a minimum. Where the

slope is steep, or where there is a

broad watershed above the orchard

from which a large amount of water

may flow down into the orchard during heavy rains, it may be desirable

to build terraces. Terraces check

the flow of water down the slope,

cause much of it to percolate into

the soil, and divert the remainder

into drainage ditches or flumes. A

system of terraces should be planned

before, rather than after, the orchard is planted.

For conunercial peach production, the trees should be set no closer

than 20 by 20 feet if the orchard is

planted on the square. Even trees

planted this far apart are frequently

crowded by the time they are 8 years

old (fig. 4). On fertile soils capable of producing vigorous trees, a

spacing of 24 by 24 feet, 20 by 25

16
FIGURE 4.—Peach orchard that lacks enough space between rows. This makes spraying,

cultivating, harvesting, and other operations difficult and ineFficient.

' feet, or 25 by 25 feet or more is

:; better than a spacing of 20 by 20

' feet. The wider spacing permits

' use of tractors and other power-

: driven machinery for laauling harroivs and spray equipment without

damaging trees and scarring

' branches. ^\niere trees are planted

on the contour, greater distance between rows permits better tree

' spacing. "Wliere modem speed

sprayers and other power equipment

are used in only one direction

through an orchard, trees are sometimes set only 16 to 18 feet apart in

the rows.

Trees planted for home us© or in

other limited areas may be spaced as

close as 15 feet apart. With the

closer spacing, tree growth may be

controlled by pruning. Pruning

Jill reduce the amount of fruit produced, but many trees may still

yield satisfactorily for home use or

local marketing.

Preparing the Site

On infertile soils it is good practice to use a green-manure crop before planting a peach orchard.

If the site is level or only gently

sloping, the soil may be disked or

plowed before the trees are planted.

Where trees are planted on the contour or where terracing between

rows is necessary, only the narrow

strips of land for planting the tree

rows need be prepared. The land

between these strips may be left uncultivated. Often in large peach

orchards, a deep furrow is prepared

for each row of trees. The furrow

is filled after the trees are planted.

When the rows have been laid out

for planting, holes are dug for the

trees. This digging requires little

effort in an area that has been furrowed for ]>lanting. The holes

should be 18 inches or more in diameter and deep enough to accommodate the root systems of the trees.

17
Soil augers operated from power

takeoff of a tractor are now used for

large plantings (fig. 5).

FIGURE 5.—Hole-digging auger used for

tree planting. Power is from the takeoff

on the tractor.

Details of methods for laying out

and terracing an orchard on the

contour can be obtained from your

local county agricultural agent or

Soil Conservation Service office.

Setting Out the Trees

Before planting peach trees, any

broken or diseased roots should be

removed. Additional root pruning

is not necessary or desirable. If the

roots have dried out in storage or in

transit, they should be soaked in

water for several hours, or overnight. Special care should be taken

to keep the roots from drying out or

freezing while they are being planted.

In setting out a tree, it should be

planted 1 or 2 inches deeper than it

was planted in the nursery. The

space around the roots should be

filled with topsoil and the soil

tamped. More topsoil should be

added if it is available and water

if the soil is dry. Nitrogen fertilizer should not be applied to the

soil at planting time.

Replanting the Orchard

Growing young peach trees on

old peach orchard sites is often unsatisfactory. Some young trees

planted on old sites die the first summer after planting. Some survive

the first season but make weak

growth and die the second or third

summer. Growth failure may be

caused by nematodes, root aphids,

diseases, poor soil drainage, low

nutrient supply, low soil pH, or

poor tree condition at planting time.

Often, however, the reason for failvire is not clear. The replanting

problem seems specific to peaches.

For example, apple or plum trees

may follow peach trees in rotation

without replanting difficulty, and

peach trees may follow apple or

plum trees satisfactorily.

Special care of young replanted

trees and use of fertilizer, especially

nitrogen, in the early suimner are

sometimes helpful.

At Beltsville, Md., applying:

about 1 ton of lime per acre to the

old field soil has been satisfactory.

Fumigating the old field with

methyl bromide has also helped.

Some root damage to replanted

trees, especially in the Southeast, is

due to mushroom root rot {Chtocyhe tabescens). Where nemiv

todes are numerous, especially those :

of the root-knot type, soil fumigation with Nemagon is helpful. In

addition, use of nematode-resistant

rootstocks is advisable. More research is needed on replanting because of necessary reuse of good

peach sites.

TRAINING AND PRUNING

In the United States, the trend is ing of old trees. After the scaffold

toward less severe pruning of young limbs have been selected, the tree

peach trees and more severe prun- should be pruned only lightly until

18
it starts to bear fruit. Even then,

to obtain highest yields of highquaUty fruit, pruning should be

very light during the early bearing

years. As the tree grows older and

dead twigs appear, the branches

should be thinned and headed back

more severely to vigorous, outward-

: growing, lateral shoots.

The Young Tree

Whe7i pkmted.—Pruning cuts on

the young tree from the time it is

. set in the orchard to its early fruitmg years are mainly for training

purposes. Early training is neces-

« sary to obtain a productive, longlived tree that may be sprayed,

thinned, cultivated, harvested, and

otherwise handlecl economically.

Not all growers train their trees in

the same way because of differences

in soil or other conditions. To develop a strong, winter-hardy, longlived tree, the scaffold branches

should be selected and trained to

form wide angles with the tree

trunk.

When obtained from the nursery,

a 1-year-old peach tree is usually

2 to 6 feet tall and has few lateral

branches uniform enough to be used

as scaffold or framework branches.

After the tree is set out, its lateral

shoots should be cut back to short

stubs ha^dng one or two buds each

(fig. 6). This brings the top into

balance with the root system and

forces the tree to develop strong

shoots, some of which will be selected as scaffold branches.

Spring-planted trees should be

cut back immediately after they are

set out. l^Hiere winters are severe,

fall-planted trees should not be cut

back until late winter or early

spring.

The height to which a tree is

headed back depends partly on its

size and how well it is branched,

'^nd partly on the grower's preference. Also where winds are strong,

low-heading is desirable. Occasionally a 1-year-old nursery tree has

well-developed laterals that can be

headed back to 6 or 8 inches and

spaced to form the head. If a low,

spreading tree form is desired, the

central stems of 1-year-old trees

may be cut to a height of 12 to 18

inches if buds are present that low

on the trunk. To facilitate cultivation and other necessary orchard

work, a higher framework of

branches is sometimes preferable.

Where trees are headed back to a

height of 12 to 20 inches, the scaffold branches are usually close together on the trunk. If the tree

stem is about 36 inches long when

it is planted, scaffold branches can

be spaced farther apart on the

trunk.

Nursery trees 4 or more feet tall,

with diameters of %6 to %Q inch,

have a potentially better scaffold

system. They should be cut back

to about 36 inches, and their lateral

shoots cut back to a few buds (fig.

6). June-budded trees may not be

tall enough to need heading back.

The terminal cut should be made

just above a live bud or a vigorous

lateral branch that forms a sharp

angle with the main trunk. If the

cut is made at a lateral branch, this

branch should also be cut back to a

vigorous bud toward the outside;

and 4 to 6 inches of the branch

should be left on the trunk. All

other branches that are weak and

crooked and that have sharp-angled

crotches, should be removed. All

branches below the lowest selected

scaffold limb should also be removed.

First and second years.—Two to

four scaffold limbs should be selected in early summer of the first

growing season (fig. 7). Some

growers prefer only two scaffold

limbs opposite each other and forming a wide crotch about 20 inches

high. Others prefer three or four

scaffold limbs no closer than 5 inches

apart on the main tnmk. Furthermore, the scaffold branches should

be spaced aroimd the trunk so that

19
FIGURE 6.—Prunins the young peach tree

just after planting. Tree is headed at

about 36 inches, and all branches are cut

back to short stubs.

none is immediately above another.

It is essential that these scaifold

limbs fomi and maintain wide angles with the central trunk.

Some summer training is desirable the first season of growth.

Shoots arising near the ground can

be removed during the summer.

Undesirable shoots and lateral

branches arising in addition to the

selected scaffold limbs should be

pinched back by hand or clipped

back. Any shoots on scaffold limbs

within about 10 inches of the trunk

should also be shortened. Cutting

back these shoots, rather than removing them entirely, causes wideangled crotches in the selected scaffold limbs.

Ifthere is no summer training the

FIGURE 7.—New growth on young peach

tree about 3 weeks after planting. Scaffold

limbs may now be selected and ofner

shoots pinched back. Tree may also be

fertilized if necessary.

first season, scaffold limbs should be

selected during the dormant period

before the second growing season.

Training or corrective pruning at

this time necessitates removing a

large amount of the previous season's growth. All limbs except

those selected for the scaffold

branches should be removed entirely

or severely cut back. The wideangled limbs selected as scaffolds

may need heading back only if they

are disproportionately vigorous

compared to others. Where summer pinching removed parts oi

limbs during the previous gi'owing

20
season, the entire limbs can now be

removed. Lateral branches on the

scaffold limbs within a foot of the

trunk should also be removed.

Early training of wide crotches is

essential to obtain long-lived, productive trees witli strong branches

free frpm winter injury to the

crotch.

The topmost scaffold (or modified

leader), either as a bud or a shoot

limb just after planting, may require further training after 1 year's

growth. Like the other scaffold

Umbs, it should be trained to gi^ow

in an outward and upward direction. This can best be done by removing,or cutting back all branches

not growing in the desired direction.

The purpose of this training is to

develop an open, spreading, symmetrical, and strong tree. Pruning

after 1 year's growth in the orchard

is the best time to start training a

tree.

Occasionally much of the treetop

grows poorly the first season in the

orchard. Often a strong, vigorous

shoot arises during the summer near

the base of the tree above the

grafted bud. If this shoot is upright and forms a sharp angle with

the trunk, the original top of the

tree may be removed just above the

base ,of the new shoot. Thus, this

shoot assumes the position and function of a main stem or tree trunk.

Scaffold limbs on this shoot then are

selected as described for the original

tree after 1 year's growth.

Some peach growers use a deshooting method of summer training during the first season in the

orchard. This method is not used

as commonly now as it was a few

years ago. Deshooting requires

much time and care. With this

method, the tree should be at least

4 feet tall when planted. The tree

IS first headed to about 38 inches,

i^nd all branches are removed below

14 inches from the tree base. The

'Other branches are cut back to one

or two buds from the trunk. During early smiimer, when the new

shoots are about 6 inches long, four

or five of the most vigorous, wideangled shoots spaced about 6 inches

apart are selected. All other shOjOts

are removed.

A modification of this method is

to remove only those shoots that will

obviously make poor scaffold limbs.

This w,ould include removing the

very weak shoots, those with narrow

crotches, and those growing in the

wrong direction. The remaining

branches (possibly 8 or 10) are allowed to grow during the first summer, and scaffolds are selected when

the trees are prmied the following

winter. AVlien using the desho,oting

method, it is preferable to prune the

tree several times during the summer and remove undesirable shoots

that develop.

During early simmier of the second year, new shoots growing from

the tnmk should be removed except

where one is necessary for a scaffold

limb. Only light thinning put of

limbs and only occasional cutting

back to outward growing limbs are

required to obtain a well-opened

tree the third year.

The Bearing Tree

The young 'bearing tree,—After

carefully pnining and training the

peach tree the first 2 years, little

pruning should be necessary for several seasons. A good scaffold system will be well established, and a

spreading-branch habit will be encouraged by the weight of the fruit

on the limbs. Aft^r the second

growing season, only light, corrective pnming will be required to keep

the center open and the main

branches well spaced (fig. 8). The

short branches bear the large fruit

buds growing near the base of the

large scaffold limbs. Where there

are a large number of branches, they

may be thinned out to permit light

to reach the tree center. Not all

should be removed, however, since

21
FIGURE 8.—A 2-year-old peach tree after pruning. Vigorous branch growth is pruned

lightly to outside shoots or not at all.

they are usually the first twigs to

bear fruit. If they are all removed,

the fruit-bearing potential of the

tree is delayed unnecessarily.

After fruiting begins throughout

the tree, the inside twigs should be

thinned out and shortened to prevent shading of the tree center.

Shading prevents desirable new

shoot growth in the tree head as well

as development of highly colored

fruits.

A well-trained peach tree will

often bear a few fruits the second

year, and a peck to a bushel of good

fruits the third year. Pruning the

fourth and fifth years should still

be light enough to train the tree to a

spi-eading, symmetrical shape (figs.

9,10, and 11 ). Pruning is not done

in the summer, although a small

number of shoots may be removed

to prevent dense inside growth.

When pruning peach trees, remember that the flowers and fnut

are borne on wood produced the

previous year. This fruiting wood

tends to grow farther out on the

ends of the branches each year.

Thus it is best to prune every year tfl

keep the trees witliin bomids and to

prevent the branches from breaking.

Furthermore, there is no better way

to stimulate the growth of the 1-

year fruiting wood in the center of

the tree than by thinning out and

heading back the inside branches

(%-12).

Peach pruning after the third

and fourth growing seasons is

mainly correctional. Removing or

cutting back branches that interfere

22
FIGURE 9.—Strong, wide-angled crotch in a

4-year-old peach tree. This type of crotch

is resistant to winter injury and to breakage

by weight of the fruit.

with the upward and outward

spread of the main scaffold limbs is

necessary. Emphasis is on light

pruning and framework development. Where it is necessary to

head back a scaffold limb to change

its direction, the cut should always

be made to an outside lateral branch

,, growing away from the center of

. the tree. A 4- to 5-year-old tree

, pruned in this way is open and has

fruiting wood throughout (fig. 12).

Wien the number of flowerbuds

. IS small, as on very vigorous young

trees or following winter budkill-

; ing, pruning should be light. If,

however, all flowerbuds have been

killed, young bearing trees may require fairly severe pruning to maintain a spreading growth. Because

fruit crops aid in spreading the

branches, young trees with many

flowerbuds need little or no heading

of scaffold limbs. No pruning at all

the first 5 to 7 years results in the

largest trees and the highest production during that period. The trees

become shaded in the centers, however, and fruiting wood is confined

to the outside and top of the trees.

Correct pruning and training during this period develop strong,

long-lived, and hardy trees. Only

light heading back and moderate

opening of the center of the trees

are necessary to encourage spreading growth and to admit light.

The mature tree.—Pruning the

mature peach tree annually is desirable to keep it relatively low, to

encourage well-distributed fruiting

wood, and to obtain high-quality

fruit. Bearing peach trees are

pruned more severely than are

apple, pear, cherry, or plum trees.

Enough branches must be removed

to permit light and air to reach the

tree. First remove dead, injured,

and weak branches. Then remove

enough healthy branches to give the

desired spacing of branches.

Pruning, however, is only one of

several factors that help produce

satisfactory tree growth and fruit

quality. Other important factors

are soil fertility, soil moisture, control of insects and diseases, and fruit

thinning.

During a single season, vigorous,

well-grown peach trees often develop upright shoots 2 to 5 feet long

in the center of the tree. These

shoots should be removed entirely ;

otherwise, they soon shade out the

more productive fruiting wood underneath. The more desirable

fruiting branches in the center of

the tree should usually be thinned

out and headed back lightly to a

vigorous shoot (fig. 13). Fruiting

wood throughout the tree should be

thinned out to keep the tree open

enough to maintain growth of new

wood each year. The amount of

necessary thinning out depends on

soil fertility, quality of fruit produced, and amount of dead wood in

the tree. If the size and appearance of the fruit are poor and there

are many dead twigs in the center

of the tree, the tree should be

thinned out or some branches removed.

23

757-340 a-H65-
FIGURE 10.—Strong, wide-angled crotches in a 4-year-old peach tree trained to the modiFied

leader system. Both this system and the system shown in figure 9 develop strong trees.

A peach tree reaches its most

economical height when it is 6 to 8

years old. Trees are allowed to

grow to 12 to 14 feet in some areas,

and only to 7 feet in other areas.

"\^1iere the soil is deep and fertile

and moisture is plentiful, trees may

be allowed to grow high and broad.

In areas where soil moisture is often

limited and soil fei-tility is low,

small, low trees are l>est for securing annual vigorous renewal wood.

The size and height of the tree are

sometimes based on local customs;

and local methods are used for

pruning, thinning, and spraying

the trees, and for harvesting the

crop. In areas where orchard sites

are relatively inexpensive, trees are

often headed low in spite of the

usually smaller yields produced on

low trees. Orchard workers who

prune, thin, and harvest fruit from

high trees sometimes object to

working from stepladders. In general, the most satisfactoi7 tree

height is between 8 and 10 feet.

The mature peach tree requu'es

more pnining than does any other

fruit tree. Pruning is largely a renewal process and is done by removing upright branches, by tlun24
: 11.—Weak, narrow-ansled crotch in a 4-year-old peach tree. This free may split

from the weisht of its fruit, particularly followins winter damo3e to the ---'-'^

FIGURE 11.-Weak

ning out shoots, and by occasionally

removing large branches of 2- to 3-

year-old wood. The main branches

of mature trees should never be cut

back to upright or outward-extendmg stubs.

The practice of heading back all

branches and shoots is not advisable. The renewal pruning method

resuhs in an open-topped tree capable of producing high-quality

fruits.

By using the renewal piiining

method, trees may be kept 8 to 10

feet tall. Only short stepladders

are then needed to prune, thin, and

harvest the fruit by hand. At this

height, the largest branch on each

well-developed crotch is removed

just above or at the side of an outward branching lateral. Tliis point

ar-oia peacn rree. inis rree m

ns winter domase to the crotch.

at the crotch is used as a base for the

renew^al height (or "renewal

point") of the tree top. Two or

more branches usually develop the

following summer at this renew^al

point ; then all branches except one

outward branching shoot are removed at the next pruning. After

several years, it is necessary to

change the renewal point to one

slightly higher or one slightly lower on the lateral. Keeping the renewal points at varying heights

helps to prevent a thick-topped

tree that shades the lower inside

areas.

Usually, too many flowerbuds are

produced on the previous season's

growth. Thus pruning the newest

growth thins the fruit as well as

encourages renewal of better new

25
FIGURE 12.—A strong, vigorous, productive, 5-year-old Redhaven peach tree. Top, before

pruning; bottom, as pruning is finished.

26
fe

tvWc vs "AA^ V!

M^

\

^V'/<^ >"}

i

^^

-V.

^M

1

>-. r'^^CM'

^^

.'-u.-^*^-^,

-p-^-äiijÄ

FIGURE 13.—A strong, mature Elberta peach tree pruned to about 10 feet high. Growth

renewal points are established throughout the tree.

shoots for producing high-quality

fruit. New terminal growth each

year should be 12 to 15 inches long

throughout the mature tree. As

the tree becomes older, severe pruning is necessary to maintain the

most desirable fruiting wood.

Sometimes a fairly large branch on

the mside of the tree must be removed completely, and others must

be headed back. The presence of

short, slender, terminal shoots 6 to

8 inches long probably indicates too

little pruning. Conversely, the

presence of vigorous, annual shoots

•^0 to 40 inches long probably indicates too severe pruning. These

conditions, however, may be caused

by some other factor, such as soil

tertihty. Pruning, fertilizing, fruit

tinnning, and soil management

must be mterrelated to obtain the

most productive tree gro\vth.

Rejiivenation jyruning. — Sometimes extra-heavy pnming is required on old or neglected trees to

make them again bear profitably.

There is often a tendency to "dehorn" or "dehead" the old, weak

trees in order to rejuvenate them.

Tests have shown, however, that

trees moderately to heavily pruned

made greatest total growth of new

wood during the two seasons following treatment. After this moderate to heavy pruning, only a moderate type of thinning out and heading

back is necessary at the end of the

first season to obtain a well-shaped,

spreading tree. Also, for the nexti

several years these trees will require

only moderate pruning. Rejuvenation pruning tends to lower the tree

head. This greatly facilitates orchard operations and rapid regrowth of adequate fruiting wood.

27
Sometimes large cuts into the

best available 4- to 6-year-old

branches are necessary to lower the

height of the fruiting wood. The

method used for renewing the tops

is not well suited to inner tree

growth or to controlling tree extension. These are best accomplished

by thinning out some branches and

heading back others to vigorous laterals.

Although correct pruning will reduce the necessary amount of thinning, propping, and bracing, it will

not eliminate the need for such support in years of heavy crops.

Time of Pruning

Experiments have indicated that

most pruning should be done during the dormant season. However,

where spring frost may injure the

crop, pruning should be delayed.

Some peach growers do at least a

part, of their pruning after the

blooming period because of frost

danger. If frost kills a high percentage of the flowers, little or no

pruning is done that season. Of

course, this practice is not best for

renewing shoot growth of the tree.

Fruit yields are reduced when

mature trees are pnmed after the

full-bloom stage. Pruning at full

bloom, at ^'shuck fall," and even at

3 weeks after shuck fall will produce larger fruit than not priming

at all. Thus it seems that most

pruning should be done no later

than at full bloom. However, if no

pruning has been done, it is better

to prune late than not at all. In

areas where frost hazard is serious,

it may be preferable to prune twice :

First, to make major cuts during

the dormant season ; and second, to

thin the blossoms after the frost

danger has passed. Pruning after

full bloom increases twig growi^h,

number of leaves per fruit, and fruit

size. The later pruning is done,

however, the less it stimulates shoot

growth and the more it reduces the

amount of fruit. Spring or summer pruning of mature trees results

in little increase in fruit size and

often reduced yield.

Pruning tests have shown that no

pruning, or pruning done at shuck

fall, caused earlier fruit ripening

than did dormant pruning or pruning done 3 weeks after shuck fall.

Dormant-pnmed trees produced the

longest shoot growth and the largest

number of flowerbuds per foot

(tables).

In the more northern peach-growing sections of the United States,

Avhere midwinter killing of buds,

branches, and tree trunks sometimes

occurs, pruning should not be done

until danger of winterkilling is past.

Tree injury is often much more

severe if the trees have been pruned

before the onset of low temperatures. Furthermore, where wood

injury has resulted from winter

cold, pruning should be delayed until growth starts and the extent of

the injury can be determined. Early

and heavy heading back, or dehorning, of winter-injured trees may kill

some of them. After growth has

started, dead limbs can be safely removed. Limbs with live tissues and

growing points should be pruned

only lightly. Application of nitrogen fertilizer will be more effective

in encouraging new tissue growth

than heavy priming of sunaving

branches that were injured by the

cold.

Delayed pruning has advantages

when flowerbuds only have been

winterkilled, because the percentage

of live buds can be determined more

accurately after the buds have

swelled. Pruning can then be adjusted to the bud set. If pruning IS

delayed until near blossoming time

and few buds have been winterkilled, pruning can be heavier. The

number of blossoms and the amount

of fruit thinning needed later will

be reduced. Pruning, fertilizmg,

and fruit thinning go hand in hand.

28
TABLE 2.—Mature peach trees: Efects of time of pruning on yield, size of

fruitj earliness ofripening, shoot lengthy and number of flowerbuds {Means

of 4 years)

Time of pruning Yield per

tree

Size of

fruit

Time of

ripening i

Shoot

length

Flowerbuds

per foot

Dormant

Full bloom

Shuck fall

Three weeks after

shuck fall

Unpruned

L.S.D. (0.01)

Bushels

7.7

6. 2

5.3

4. 7

8, 2

1. 3

Number per

bushel

171

188

167

162

214

18

Percent

22. 0

39. 7

43.9

26.7

45. 0

15. 3

Inches Number

11. 6

9.7

9.0

8. 7

5. 1

1. 2

15. 1

13. 3

11. 1

11. Z

10.4

1. 5

1 Relative time of ripening based on number of fruits harvested at the first 2 of the 4

picking dates.

Pruning in Relation to Fruit Thinning

There must be a balance between

pruning and fruit-thinning practices in the peach orchard. Neither

practice alone will produce the

highest yield of top-quality fruit.

Pruning reduces the number of

fruits per tree at a time when fruit

thinning is of most value—before

the fruits have begun to compete

with each other and with the growth

of the tree.

When a pruning cut is made that

removes either the entire limb or a

part of it, flowerbuds and leafbuds

are removed with the wood. Leafbuds near the pruning cut are stimulated and grow into long, leafy

shoots. These leaves are important

to the developing fruits left on the

tree, since they are the food-producing organs. For largest peach

size, there should be at least 35

leaves for each peach. If there are

too few leaves per peach, the

peaches will be small and the color

and quality poor. Unpruned or

Hghtly pruned trees produce more

leaves per tree than do heavily

pruned trees, although the growth

inay be short. Unpruned or lightly

pruned trees will contain a relatively large number of flowers and

young growing fruits, but there will

be fewer leaves for each fruit. By

the time the fruits are thinned, the

potential size will already have been

reduced.

Pruning done largely to thin the

peaches should be well distributed.

Pruning of many small twigs is desirable. Peach trees can quickly

disseminate nutrients and food materials. The largest scaffold

branches serve as units, so that a

large leaf area anywhere on a large

branch increases fruit size over the

entire branch. Uniform fruit thinning is not necessary to increase

peach size.

Pruning in Relation to Fertilizing

In commercial orchards, soil fertilizing and pruning are both necessary for satisfactory new shoot

growth on peach trees. Pruning reduces the number of growing points

on the tree and increases individual

shoot length. Where space is limited and yield of fruit per tree is not

a major factor, pnming can keep

the tree small and maintain the desired 12 to 15 inches of annual terminal shoot growth of mature trees.

Soil fertilization, especially by

nitrogen, should be reduced as the

severity of pruning is increased.

The fruit yield per tree will also

decrease with the severity of pnming.

29
Reduction eitlier in pruning or in

nitrogen fertilization results in

short shoot growth and early fruit

ripening. Fruits of varieties with

little red color develop more color

with reduced pruning or reduced

application of nitrogen to the soil.

Fruits of bright red varieties, however, oft«n become dull and imattractive if nitrogen in the soil is low

or if the trees are lightly pruned.

Heavy pruning delays fruit ripening, as does too much nitrogen fertilizer. Their basic effects, liowever,

are different. Pruning reduces the

size and potential yield of the tre«,

whereas nitrogen fertilization tends

to increase both. Heavy pruning

often increases the percentage of potassium and other elements m peach

leaves, probably by reducing the

total leaf area in proportion to the

root area per tree.

Pruning Tools and Equipment

The use of the power, compressedair, or pneumatic pruner in many

good commercial peach orchards increases working efficiency and reduces labor costs. The power

pruner is most valuable when used

on mature trees of uniform size.

Some growers find portable platforms are especially useful with

this type of pruning operation.

Usually at least one workman

prunes from the ground. One of

the most useful tools for general

pruning is a lightweight Toppertype hand pruner about 24 inches

long. This lopper is often the only

pruning tool used by many successful peach growers. A small hand

shear is also useful for pruning

trees. Occasionally, a small saw is

used.

SOIL MANAGEMENT

Good soil management is as important for keeping trees vigorous

as is pruning. As mentioned

earlier, a deep, well-drained soil of

medium texture is highly desirable

for peach growing. On nearly level

orchard sites having this kind of

soil and having adequate air drainage, control of soil erosion is not

difficult. Soil management on more

rolling sites requires careful attention (figs. 14, 15, and 16). To obtain good air drainage, peaches are

usually planted on rolling to hilly

sites, except in the mild climates of

the Southeast, or where lakes give

protection from unfavorable temperatures. On these upland sites,

^;ÍIAÉí^^

FIGURE 14.^Sod strips across the slope in this young peach orchard protect the soil from

erosion.

30
FIGURE 15.—Low soil terraces across the

slope for each tree row help prevent soil

erosion.

HGURE 16.—A sod-mulch system as in this

peach orchard prevents soil erosion on the

steeper slopes.

the soil is frequently no more than

3 to 5 feet deep. It is customary to

cultivate the soil of peach orchards

early in the season to make nutrients

readily available to the trees. This

cultivation conserves moisture by

killing weeds and other plants that

compete with the trees for moisture.

A ground cover of growing plants

on an orchard site, however, may

serve two important purposes—it

supplies organic matter to the soil

and it prevents loss of topsoil by

erosion (figs. 17, 18, and 19). Tillage practices on any orchard site

affect the soil and moisture conservation and the organic-matter content and fertility of the soil.

No fruit trees are affected more

by lack of soil moisture and nitrogen than are peach trees. Peach

trees root extensively, and the roots

of trees planted 20 feet apart may

meet after about 5 years. Cultivation breaks down the soil organic

matter and thus releases the nutrients. The nitrogen released by

cultivation often stimulates the

trees as much as does an application

of fertilizer. Before inexpensive

nitrogenous fertilizers became

available, cultivation for this purpose was invaluaible. Now, however, it is preferable to add inorganic nitrogen and keep the organic

matter on or in the soil as long as

possible. This practice will control

erosion most effectively, maintain

soil porosity, and improve the general physical structure of the soil.

The Young Orchard

The first year after peach trees

are planted, the orchard soil should

be tended carefully to encourage

adequate root and top growth. The

soil around the trunks should be

kept free from weeds during the

growing season, especially in nonirrigated orchards. In the larger

orchards, the soil along each side pf

each row should be cultivated to a

distance of at least 5 feet (fig. 14).

It is not necessary to cultivate all

the area between tree rows. An

31

757-340 O—65-
FIGURE 17.—Rye cover crop in peach orchard ready for early sprin3 disking.

FIGURE 18.—Rye cover crop disked down correctly so that much of it remains on the soil

surface.

annual or biennial cover crop may

be grown on the cultivated strips

(fig. 17), and turned under to improve the soil. On sites that are low

in soil organic matter and subject to

soil loss through water runoff, cover

crops in the young orchard are desirable because they check soil erosion and because incorporation of

cover-crop residues makes the soil

more porous. Cover crops should

not seriously hinder growth of the

young trees if they are confined to

areas well beyond the spread of the

tree branches. Avoid deep cultivation. . .

In orchards on level ground, it is

often desirable to grow an intercrop

the first 2 or 3 years. The trees are

benefited by the cultivation of such

a crop and by the fertilizer applied

to it. In oixhard sites having

32
FIGURE 19.—Clean cultivation during early summer often results in vigorous tree growth and

large-sized fruit, but the soil can erode easily.

slopes, the intercrop should be

planted across the slope, so that

water collecting in and along the

furrows made by tillage tools will

not run off rapidly and carry away

topsoil. In the second and third

years, less space should be allotted

to an intercrop than in the first

year. Unless the trees are planted

at least 25 feet apart in both directions, an intercrop should not be

planted after the third year.

The Bearing Orchard

Cover crops.—Bearing peach

orchards are cultivated less today

than they were 25 to 30 years ago

because of the use of cover crops.

Cover crops seeded in late summer that grow during fall or winter

are best, because they do not compete with the trees at the seasons

when the trees require the most

moisture and nutrients. Eye (figs.

17 and 18) is perhaps the most commonly used cover crop for fall and

winter. It resumes growing early in

the spring and should 1^ disked

roughly before it begins to compete

seriously with the trees. Sometimes

cover crops that winterkill, such as

spring oats and millet, are grown

during late summer and early fall.

Sometimes annual weeds are allowed to grow as cover crops during

that period. The crops or weeds

are allowed to remain over winter

and are disked in early spring.

Disking, however, should not be excessive, because it \yill destroy the

value of a cover crop. To permit

water penetration and to avoid soil

erosion, as much as possible of the

cover crop should be left on the soil

surface (fig. 18).

In some locations and on certain

soils, especially where soil erosion

is likely, a summer cover crop such

as soybeans, cowpeas, and crotalaria

should be grown in addition to a

fall or winter crop, even though it

will compete with the trees and perhaps reduce the fruit crop. Summer cover crops such as late

varieties of crotalaria and buckwheat make most of their growth

after the Eedhaven season varieties

are harvested.

Cover crops should be fertilized

according to the local practice.

Often a "complete" fertilizer is applied when a cover crop is planted.

Although legumes have often

been recommended as orchard cover

crops because they add nitrogen to

the soil naturally, their use for this

purpose is too expensive.

Many commercial peach orchards

are not seeded to cover crops, but

weeds are allowed to grow m late

summer and fall. Sometimes this

33
system is fairly satisfactory, but a

seeded cover crop will usually produce more organic matter for the

soil.

Tests to determine the effects of

disking rye cover crops at different

stages of growth in a peach orcliard

showed that late disking intensified

the red of Elberta peaches but had

no significant effect on the color of

some of the more highly colored

peach varieties. Soil erosion was

controlled more effectively by late

disking of the cover crop than by

early disking. Soil moisture and

available nitrogen were reduced by

late disking, but not enough to affect

the size and yield of the fruit or the

growth of the trees.

Where root-knot nematodes are

harmful to peaches, nematode-susceptible cover crops such as cowpeas,

vetch, rye, and Austrian winter peas

should be avoided. Resistant crops,

such as crotalaria in the later summer and oats in the winter, may be

used. Native weeds allowed to

grow during late summer after harvest and disked in midwinter are

preferable to a cover crop susceptible to nematodes. AVliere nematodes are serious and soil erosion is

not, clean cultivation throughout

most, of the year is recommended.

Damage from spring frost during

the pink-through-bloom-and-petalfall period is sometimes reduced by

maintaining a hard, bare soil surface. In level peach-growing areas,

such as the Coastal Plain, an orchard planted with a cover crop is

sometimes l"* to 3^ cooler than one

without a cover crop. A recently

cultivated orchard is just as subject

to frost damage as is one planted

with a cover crop. Bare, hard soil

provides a heat reservoir from

which heat is radiated at night. If

the soil is covered by weeds, cover

crop, or mulch, or if it has recently

been cultivated, radiation is impaired. In level areas where spring

frosts may occur, orchards are clean

cultivated in midwinter or very

34

early spring in time for rains to

pack the soil well before frost

danger.

Permanent or semiper?ru¿7ient

crops.—Sod is sometimes used as a

cover crop in peach orchards, but its

use is not recommended because it

often reduces the growth of trees

and fruit, ^^^lere abundant water

is available from rain, from irrigation, or from an unusually de^p soil,

a pennanent cover is sometimes satisfactory. This is not true, however, in most of the Eastern and

Southern States.

The use of soil nutrients by the

sod is less serious than its use of water, since nutrients may be added as

fertilizer. A nonlegume sod-covered orchard area requires about

three times as much nitrogen as one

under cultivation, because the soil

uses so much nitrogen. A mulch

helps conserve moisture in the

sodded peach orchard (fig. 16).

Peach trees, however, root extensively ; and the sod may compete for

moisture with roots as far as 12 to

15 feet away from the tree trunk.

Some peach growers use a sod

cover but disk the sod well every

few years. Others use sod strips

across the slope between wide, cultivated peach rows (fig. 14). The

sod strips control erosion, and cultivation reduces competition with the

trees. The sodded strips provide

useful surfaces for mo\âng sprayers

and harvesting equipment, especially during wet weather. Orchard sod should be fertilized and

mowed occasionally.

In soil-management studies made

at Beltsville, Md., over a 12-year

period, cultivation of soil in peach

orchards during: the summer was

more effective than use of a summer cover crop. Annual cover

crops were more effective than were

semipermanent sods of sweetclover

or lespedeza. Soil moisture seemed

to be the principal limiting factor.

Either system of sod culture reduced tree growth and decreased
yield and size of fruits, even in mature trees.

Some compromise between a system of clean cultiA^ation and continuous use of sod is possible. Shallow disking two or three times a

year is usually satisfactory. For

best results, the needs of each orchard should be considered individually.

Soil and moisture conservation in

peach orchards is very important.

Contour planting is often necessary, and sometimes terraces are

needed (fig. 15). Much depends on

the soil type, the amount and distribution of rainfall, and the percentage of land slope. Soil and

moisture losses are easily overlooked; it is Avise sometimes to risk

reducing tree growth for the sake

of soil conservation.

FERTILIZERS

There are 12 known nutrient elements necessary for plant growth.

The major nutrient elements, or

macroelements, needed by peach

trees include nitrogen, potassium,

phosphorus, magnesium, and calcium. The minor nutrient elements, or microelements, include

zinc, boron, maganese, copper,

iron, sulfur, and molybdenum. A

minor element is just as essential as

a major one, but less of it is required.

Nitrogen remains the chief fertiUzer element needed by peach orchards on most soils. Potassium is

perhaps the next element most

needed. The elements most needed,

and the rates at which they should

be applied, vary widely according

to soil type and other factors.

A fertilizer program should be

planned to cover the complete life

of the orchard. A balance of all

nutrient elements, but especially of

nitrogen, potassium, and magnesium, is important. However,

only those materials needed by the

trees that are not supplied by the

soil should be added. Usually fertilizers are applied to the soil, but

some may be applied to the tree as

foliar sprays.

Nitrogen

Nitrogen deficiency symptoms

are small, pale-green leaves, sometimes yellow with red specks; short,

thin shoot growth ; and small, earlyripening, highly colored fruits.

Lack of nitrogen absorption and

translocation because of root or limb

damage or poor soil drainage also

produces these same symptoms.

For satisfactory^ tree growth and

production, nitrogen should be

added to soils in all peach orchards

east of the Rocky Mountains. The

amount needed varies considerably.

To obtain high-quality peaches,

the soil nitrogen level should be

neither extremely high nor extremely low. The level may be regulated

somewhat by the use of cover crops

as well as by the amount of nitrogen

fertilizer applied and the time of

application. For the brightest

fruit color, the soil nitrogen level

should never be extremely high.

Where color is important, the nitrogen necessary for tree growth

should be applied in the fall rather

than in the late spring or early summer. The effect of nitrogen on color is important in such varieties as

Elberta, Sullivan's Early Elberta,

and Belle; but Redglobe, Dixired,

and certain other varieties color well

when relatively high soil and tree

nitrogen are present. The time

when nitrogen is available to the

tree roots is the critical factor ; this

depends partly on when enough

water is available to carry the

soluble nitrogen to the roots.

Treatments that supply abundant

nitrogen in midsummer should be

avoided.

A high soil nitrogen level in earlj

spring is necessary for vigorous foliage growth and large peaches, but

high available nitrogen in late

spring delays fruit ripening.

35
In some orchards, nitrogen is the

only fertilizer needed. Because the

amount needed varies greatly, no

specific recommendation can be

made. Growth of the tree, together

with yield, size, and quality of fruit,

is the best criterion to determine

required amounts of fertilizers,

especially nitrogen. A suggested

amount w^ould be one-eighth of a

pound of actual nitrogen per year

of the tree's age, up to 1 pound per

tree-. For example, the 8-year-old

tree w^ould receive 6 pounds of nitrate of soda (16 percent nitrogen),

3 pounds of ammonium nitrate (33

percent nitrogen), or 2.2 pounds of

urea (45 percent nitrogen). These

nitrogen sources may be selected on

the basis of availability and economy, since all are equally effective.

High-nitrogen fertilizers are soluble

in water and will penetrate to the

tree roots soon after rain or irrigation.

The fertilizer should be spread

evenly mider the tree and should extend just beyond the tips of the

branches. Cover crops are improved if the fertilizer is spread

over a wader area throughout the

orchard, but more fertilizer wall be

required per acre. A complete fertilizer is necessaiy in some areas.

One pound of actual nitrogen is obtained in 10 pounds of a 10-10-10

fertilizer. Careful obsen^ation and

advice of local extension or experiment station workers will help determine whether the phosphorus

and potassium contained in such a

fertilizer is economical.

Foliage sprays containing nitrogen for fertilizing peaches have

been tested with little success.

Peach leaves evidently do not absorb the nutrient as efficiently as do

apple leaves.

Some successful peach growlers

apply nitrogen only in the late summer or fall. Others apply all the

nitrogen early in the spring. Still

others apply part in the fall and

part in the spring. The loss of

36

fruit color resulting from the second method depends on the variety,

tlie soil type, and the amount of

nitrogen used. With a potentially

higlily colored variety, a sandy soil,

and a moderate amount of nitrogen,

there may be no reduction in fruit

color.

Tests wûth Elberta, Halehaven,

and Triogem varieties at Beltsville,

Md., emphasized the interrelations

of variety, time of nitrogen application, and time of disking the cover

crop.

When nitrogen was applied to

trees in the fall, the fruit yield was

reduced and the fruit ripened earlier than when it was applied in the

spring, or when it was applied in

three equal amounts in the fall, the

spring, and the early summer.

Yields were usually highest when

nitrogen was applied in three equal

amounts. The time of disking the

lye cover crop had little effect on

fruit yield of any of the three varieties studied. A full crop of

Elberta peaches yielded more than

did Halehaven or Triogem. Differences in fruit size due to fertilizer and disking treatments were

not consistent. The Triogem

peaches, howeA^er, were consistently

smaller than those of the other two

varieties. Fall fertilizing and late

disking resulted in the deepest red

skin color of Elberta peaches. The

treatments did not seem to affect the

color of Halehaven and Triogem

peaches.

Fruit ripened earliest when fertilized in the fall, but time of ripening w^as unaffected by disking time.

The leaf-nitrogen content in August

w^as greater wdien fertilizer was applied in the three equal installments

than when it was applied in the fall.

Time of disking the rye did not affect the nitrogen content of the

leaves, which w^as relatively high

regardless of treatments.

The divided applications of nitrogen are especially useful on

sandy soils subject to rapid leaching
of moisture and nutrients. Also,

divided applications allow for better nutrient management based on

crop needs. For example, if the

fnut set after bloom is heavy, more

nitrogen can be applied than if

there is a light set follo^Ying a severe

frost. In the southern areas, at

. least part, of the annual nitrogen

required can be applied just after

; harvest. However, in the northern

1 areas, nitrogen applied after harvest may increase winter injury.

! Potassium, Phosphorus, Magnesium,

and Calcium

There is almost as much potassium as nitrogen in peach leaves.

In many peach-growing areas, trees

get as much potassium as they need

without fertilizing. In some areas,

such as much of the Atlantic

Coastal Plain extending from New

Jersey to Florida, trees often require additional potassium. In

other areas, the need for potassium

fertilizer for peaches varies. Severe potassium deficiency causes

slender shoot growth, and rolling,

puckering, and marginal burn of

leaves (fig. 20). Mild deficiency,

however, reduces fruit size and

yield. In early spring, potassium

may be applied to the soil surface

under the tree at the rate of 2 to 4

pounds of either muriate or sulfate

of potash. It can be applied also

in a compílete fertilizer such as

10-10-10.

Phosphorus in peach-orchard

soils is often low, but it is rarely

necessai-y to add any for the peach

tree. Peaches, as well as other

fruits, are able to obtain the phosphorus they require where annual

crops will show a severe need for

phosphorus fertilization.

FIGURE 20.—Potassium-deficient peach leaves. Left to risht: Leaves with increasingly severe symptoms of potassium deficiency.

37
Äiagnesium deficiency in peaches

(fig. 21) is found mainly in the

sandy Coastal Plain soils, especially

following heavy potassium fertilization. The first indication of this

deficiency is a light yellowing between veins of the leaf. In severe

cases, death of the yellowed areas is

accompanied by a marginal leaf

burning. Usually the more basal

leaves are alïected first. Foliar

spraying with about 10 pounds of

magnesium sulfate (Epsom salts)

per 100 gallons of water usually

gives prompt control. Application

of dolomitic limestone to the soil at

about 2 tons per acre will often control the deficiency within a few

years.

Calcium is sometimes needed as a

fertilizer for peaches, especially in

Coastal Plain soils where large

amounts of sulfur have been used to

spray peaches for disease control.

Calcium reduces soil acidity, and

this, in turn, increases the availability of many soil elements and root

growth (fig. 22). Although peach

trees grow well in acid soils, the pH

should not be below about 4.5. Very

high soil calcium reduces absorption

of potassium and magnesium by the

roots. Soil acidity can be corrected

FIGURE 21.—Left to right: Increasingly severe symptoms of magnesium deficiency in peach

leaves.

38
FIGURE 22.—Effects of (A) low, (B) medium, and (C) high levels of calcium on peach roots

grown In orchard soils at Beltsville, Md.

by adding limestone according to

local recommendations.

Zinc, Boron, and Manganese

j Zinc deficiency sometimes occurs

I in peach trees grown in sandy soils

of the Carolinas and Georgia, but it

IS much more common in the Western States. Symptoms of this deficiency are light yellow, wavy, and

cnnkled leaves, with rosettes at the

tips of the twigs. In severe cases of

zinc deficiency, leaves are very

small.

Boron deficiency causes twig

death, lack of bud growth, and

sometimes dark-brown cork spots

in the fruits. It occurs only occasionally in Eastern United States.

Manganese deficiency causes

light-yellow areas between the veins

of the younger leaves toward the

tips of the shoots. Deficiencies in

all these microelements can usually

be corrected by foliar sprays used

according to local recommendations.

Copper, iron, sulfur, and molybdenum usually occur in ample quantities in most orchard soils.

All the chemicals mentioned are assumed to be

caustic and poisonous ; some

are flammable. They should

be kept dry and handled

with care to prevent fire or

explosion.

IRRIGATION

Many peach orchards east of the sprinkling equipment has aided

Aocky Mountains are now irrigated. o:reatly in making orchard irrigaiiicreased efficiency in pumping and tion economically practical. Many

39
successful peach powers in the East

now consider irrigation an essential

part, of their soil management program. Irrigation is planned and

used according to needs of the trees

and capacity of the soil.

A short, period of dry weather,

especially during the final month

before harvest, will sharply reduce

fruit size and quality of peach trees

growing in shallow soil. Low soil

moisture during early summer affects fruit size and yield and also

affects next year's crop by reducing

the terminal growth of shoots and

by weakening the trees. Peaches

from irrigated trees ripen a few

days earlier and ripen more uniformly than do those from nonirrigated trees.

In most of the Eastern United

States, winter rains fill the soil to its

maximum water-holding capacity

by spring. Thus, peach trees startthe growing season with adequate

moisture. The amount of water the

soil can hold depends mostly on soil

texture and depth. This varies

from about 1 acre-inch of water per

foot for sandy-loam soils to about

2 acre-inches per foot for clay loams.

Thus, if the root-depth zone is 4 feet

in a silt-loam soil, there will be

about 6 acre-inches of water available in the spring. Eastern peach

orchards use about 3 acre-inches of

water per month during the growing season. Thus, the available soil

water would last about 2 months

without additional rain. Peach

trees need water most during the

montli just before harvest, when the

moisture requirement for fruit size

is greatest.

Development of a water supply

and cost of equipment and maintenance are expensive. Irrigation

will be least economical where the

root depth is great, the soil is fairly

heavy, and an early ripening peach

variety is grown. But where a

good supply of water is available at

moderate cost and the root depth is

as shallow as 2 to 3 feet, irrigation

should increase peach production in

most years.

If rainfall has averaged less than

1 inch per week for about 3 weeks,

irrigation may be needed, especially close to harvesttime. When

irrigating, completely wet the soil

to the root depth. Light, sandy

soils may lose nutrients because of

too much irrigation, but they need

more frequent irrigation than do

heavier soils. Irrigating any soil

too much or too often can damage

peach tree roots. Learning to irrigate properly requires careful study

and much experience.

THINNING THE FRUIT

Fruit thinning is necessary to

produce high-quality peaches, especially in years of heavy crops. The

extent of thinning depends somewhat on the potential size of the mature fruit of the particular variety.

In general, the smaller the normal

size of the fruit at maturity, the

wider the spacing to which the fruit

should be thinned on the twigs.

The correct thinning distance depends partly on the leaf area per

fruit and the general vigor of the

tree. It takes about 35 healthy,

average-sized green leaves to produce a peach of good size and

quality. In thinning, only one

peach should be left to every 6 or

8 inches of twig. Although this

may seem drastic and expensive, it

must be remembered that small

peaches are often hard to sell.

Also, thinning lessens the harvesting work and the danger of limbs

breaking under the weight of fruit.

Thinning According to Variety

With the early ripening peach

varieties that tend to set a heavy

load of fruit, thinning well before

the June drop greatly increases

40
fruit size and earliness of ripening

(fig. 23). These early ripening

varieties have a much shorter period

of fruit development than do Elberta and the later ripening varieties. Varieties that particularly

benefit from early thinning include

Mayflower, Earlired, Cardinal,

Coronet, Redhaven, Golden Jubilee,

and Triogem. With tliese early

ripening varieties, early thinning of

fruit increases not only fruit size

but also quantity of young-shoot

growth and leaf size.

TIME OF THINNING REDHAVEN

Bloom 2 4 6 8 10 )2

WEEKS AfTER BLOOM

2

MATURITY EFFECT .

Ï 80 - -

Î 40 _ 1 0.

0 1 1 1 1 1 Bloom 2 4 6 8 10 12

WEEiS AFTER BLOOM

FIGURE 23.-.Eifects of time of thinning on

fruit size (top) and maturity (bottom; of

Redhoven peacfies. Each successive thinning period caused smaller and later ripening peaches.

For many early ripening varieties, if thinning is delayed much

after the pits begin to harden, the

final size of the fruit may not be

greatly increased. This is especially true if dry weather prevails

during the early part of the growing season and at harvesttime.

Growers must determine if the

greater value of the larger fruits

justifies the expense of early

thinning.

. With midseason and later varieties, the usual practice is to wait

until after the first drop and then

remove many of the small and imperfect fruits. Experiments with

Elberta peach trees have shown

that if the fruit set is only moderate

and the drop in June is fairly

heavy, thinning done as quickly as

possible after the .June drop usually

results in fruits of good size and

color. If thinning is delayed until

well along in the pit-hardening

period, it still has a beneficial effect

on the final size of the fruit. If

thinning is done as late as the period

of final swell, it still increases the

size of the remaining peaches.

Elberta trees bearing a large crop

should be thinned just as soon as

possible after the first drop. When

thinning is done quickly near the

end of the first growth period (before pit hardening), the result is

almost as satisfactory as it is with

earlier thinning. The cost is much

less, because some of the peaches

will drop anyway.

Amount To Thin

How many peaches should be removed from a tree by thinning depends chieñy on the size of the tree

and its bearing capacity. If a tree

cannot bear more than 1 or 2

bushels, only enough of the peaches

that can develop to desirable size

(those with a diameter of 2^/4 to 21/^

inches) should be left to make up

this quantity. When a tree has a

uniformly heavy set of fruit, it can

be thinned to a fixed spacing, such

as 6 to 8 inches along the twig.

Usually, it is best to thin not according to a fixed spacing but according to leaf area, tree vigor, and

bearing capacity. After a spring

freeze, sometimes the only blossoms

left alive are those at the bases of

terminal shoots. Wlien this happens, the fruits are not thinned even

Avhere they touch each other, because the leaf area is sufficient for

all.

41
Methods of Thinning

Where labor costs are high, peach

growers may choose to reduce the

number of peaches that will be produced on their trees by pruning off

a large number of shoots either before or at blossomtime. In localities where spring frosts occur, some

detailed pruning may be postponed

until blossomtime, when crop prospects are more certain.

Recently, because of high labor

costs, considerable thinning has

been done by rapid mechanical

methods rather than by the older hand method. Some growers

now use poles 4 to 8 feet long or

longer, with about 12 inches of hard

rubber hose over one end. With

such poles, the excess fruits are removed by tapping the branch or

twig first at right angles and then

lengthwise. Wire or brush brooms

are sometimes used to thin peach

blossoms, especially those of early

ripening varieties.

Several types of chemical sprays

have been tested, some of which thin

late and after danger of frost.

However, none is depeoidable

enough to be recommended for

prax^tical use. Elgetol is one of

the chemical thinning sprays that

has been used extensively, although its results are not always

reliable. If Elgetol is used, spraying should be done at full blooom.

The suggested strength is 1 pint of

Elgetol per 100 gallons of water.

Blossoms should not be thinned

by any method if it is likely that

some may be killed by frost.

The most experienced growers prefer to do only part of a necessary

thinning by mechanical methods

and then to follow up with hand

thinning.

LOW-TEMPERATURE INJURY

Low-temperature injury is one of

the greatest problems of peach

growers in both the North and the

South. Almost every year, serious

winter injury of peach trees occurs

in one or more sections of the coujitry (fig. 24). Often winter injury

is not recognized as such, for it can

occur when temperatures have not

been unusually low. For example,

rapid drops in winter temperatures

from about 70° F. during the day

to about 18'' F. at night have caused

severe damage to peach tree- wood

in southern areas. In northern

areas, the damage is likely to occur

only at much lower temperatures;

and dormant flowerbuds are affected before the wood is. A rapid

drop to temperatures below -15°

F. often injures twigs and trunks

as well as buds. Sometimes, in

peach orchards having no ground

cover, prolonged low temperatures

damage even the tree roots.

In both northern and southern

peach-producing localities, winter

injury seems to be least among

moderately vigorous trees that

grew w^ell the previous season and

that were not weakened by poor

drainage, loss of leaves, borers,

nematodes, or other factors.

Injury to Buds

The most common type of winter

injury to peaches in the Northern

States is killmg of dormant flowerbuds. Leafbuds are seldom injured.

There is no fixed minimiun temperature at which dormant flowerbuds

are destroyed. Much depends on

the tree growth during the previous

growing season, age and idgor of

tree, variety, state of flowerbud development, rapidity of temperature

drop and time of its occurrence, and

duration of the low temperature.

During midwinter, the critical low

temperature for Elberta peaches is

about -10° F. However, a rapid

drop in temperature aft^r a warm

period can lead to budkilling at

temperatures much higher than

-10"^. Conversely, buds have some42
FIGURE 24.—Winter clamase, primarily on the southwest side of the tree trunk and lower

parts of scaffold limbs, caused by rapid temperature changes. Reflection of sun by snow

causes surface temperatures considerably above air temperature.

' times survived temperatures belovs?

-15° in midwinter when the drop

was slow and when it followed a

period of relatively cold weather.

Differences in flowerbiid hardiness between peach varieties sometimes mean the difference between

a good peach crop and no peach

crop. Elberta and J. H. Hale are

two of the more tender varieties.

Rochester, Veteran, Cumberland,

and Erly-Red-Fre are among the

more hardy varieties. Halehaven,

Golden Jubilee, and Redhaven may

be classed as fairly hardy. Some

varieties such as Ranger, Redhaven,

and Cumberland often bear fair-togood crops after large percentages

of the buds have been killed, because they characteristically have

iarge numbers of buds per foot of

twig length. Some varieties have

so few buds that killing even a small

percentage may make a good crop

impossible.

Usually there is greater bud mortality on trees having weak growth.

Even where there is some difference

in tree growth because of different

fertilization, however, there is often

little or no difference in bud survival during midwinter.

In many parts of the country,

especially in the Central and Southern States, damage often results

from low temperatures during or

after bloom. As flowerbuds develop

in the spring, they quickly become

more sensitive to cold. Just before

they open, flowerbuds will sundve

temperatures of about 20° to 23° F.

The lowest temperature flowers will

withstand at full bloom is about 26°.

Ten days to 2 weeks after bloom,

they will withstand only about 28°.

Buds and flowers will survive temperatures slightly loAver than these

if the drop is very slow and if the

minimum temperature continues

only for a very short time.

43
Accurate thermometers should be

used in the orchards. Early spring

temperatures, especially on hillsides, are not uniform even at points

only 50 feet apart. The higher part,

of a sloping site is usually much

Avarmer than is the lower part-, since

cold air drains downward. A 50-

foot difference in elevation on a hillside may mean a difference of as

much as 5"^ F. in minimum temperature on a still night.

Injury to Twigs, Branches, and

Trunks

Even in some of the most southern

peach areas, and during mild winters, wood killing is often serious.

Injury is caused by rapid drop in

temperature and by immaturity of

new wood growth produced in late

summer or early fall from the stimulation of high soil nitrogen content, recent heavy pruning, or other

factors. Peach trees develop resistance to cold only if they are exposed gradually to low temperatures. Trees that have grown

poorly for any reason are especially

subject to winter injury to trunks

and branches. Weak growth and

the resulting winter injury are

caused by poor soil drainage, nematode injury to roots, low soil fertility, insect damage, and disease.

The critical temperature at which

wood injury may occur is not specific. Serious trunk damage has resulted from -SO"" F. temperature

in northern areas during certain

years. In both northern and southern peach-growing regions, the least

low-temperature damage seems to

occur in trees of moderate vigor and

where there are no sudden changes

in temperature.

Even though wood appears to

have been damaged by wmter cold,

much of it may survive if the trees

are not pruned too early or too severely and if readily available nitrogen is applied to the soil at a

somewhat heavier than usual rate.

If bark on the trunk is found to be

loose after a severe drop in temperature, it should be tacked in

place immediately. This sometimes prevents the bark and wood

from drying out, and it may hasten

healing. When large branches or

trunks have been severely damaged,

the injured parts should be painted

with a standard tree paint—white

lead and raw linseed oil, or a liquid

(brush) grafting wax.

Injury to Roots

Cold injury to peach tree roots

is often overlooked or disregarded.

Winter injury to roots is usually

more severe in light, sandy soils and

after prolonged cold. It is much

worse where there is no snow or

other covering on the ground.

Cover crops are valuable in preventing this type of injury. In addition to directly insulatmg the roots

from cold, cover crops tend to hold

protective snow in place. After severe damage to roots, tops should be

given a moderately heavy pruning.

Although freezing of orchard soil

may not kill tree roots, it may retard their absorption of water during the winter. Trees grown in

light shallow soils in more northern States are, of course, most likely

to be injured by soil freezing.

HARVESTING, TRANSPORTING, AND STORING FRUIT'

The peach grower's choice of a nxore mature peaches than formerly

time to pick his crop depends because their eating quality is betlargely on how he intends to market ter. If peaches are to be trucked to

it. The current trend is to pick nearby markets, they may be al-

' This sectton was originaUy prepared by M. H. HaUer. Revised by W. H. Bedit

and W. L. Smith, Jr. Market Quality Research Division.

44
lowed to become nearly ripe on the

trees. For shipping greater distances, most peaches are picked in

the firm ripe stage and pi-ecooled

before shipment. During transit,

this fruit should be maintained at

or below the precooling temperature

to delay ripening and thus reduce

bruising. Because peaches mature

unevenly, it is usually advisable to

make several pickings, beginning

with the largest, best-colored fruit.

For freestone varieties, standards of

maturity are based on the change of

ground color from green to yellow

and on flesh firmness, as determined

by using a Magness-Taylor pressure

tester (fig. 25). Elberta peaches

testing 10 to 14 pounds with a %Qinch-diameter plunger applied to

the pared cheeks will hold up in refrigerated shipment for several

days and will ripen with satisfactory dessert quality. For nearby

marketing, less firmness may be desirable. About the same range in

pressure testing is satisfactory for

many varieties other than Elberta.

Drop-bottom picking bags are

now widely used for peaches.

Padded, drop-bottom picking buckets (fig. 26) afford greater protection from bruising Pickers should

exercise great care in handlinopeaches to avoid bruising the frait

and breaking the skin. They must

be careful not to drop fruit, either

when placing it in picking buckets

or bags or when transferring it to

field ci-ates. Picked fruit should be

left in the shade of a tree until it

can be hauled to the packinghouse.

Tub baskets, particularly the %-

bushel size, with vented liners and

cushioning pads are the most commonly used shipping container for

eastern peaches. Howe\'er, they

have these undesirable features:

Peaches in the bottom, especially if

they are ripe and soft, are likely to

be bi-uised and mashed by the

weight of those above them ; peaches

on the top are often cut and brused

by the rim of the lid ; and tub baskets are not rigid and do not stack

well. Peaches in these baskets are

usually "faced," which adds considerably to the cost. To meet the demand of "nonfacing" and to try to

reduce bruising, a new type of tub

FIGURE 25.—Pressure tester used to determine maturity of peaches.

45
FIGURE 26.—Harvesting peaches in a dropbottom picking bucket designed to prevent

bruising.

basket, the "flat-top" or "PalletPak," also has been widely tested.

This basket has no handles. The

sides are raised and the lid is placed

so as to prevent the normal bulge

present in the conventional tub basket. Stacking quality is improved,

also.

Wirebound crates have been

tested, and some are gaining popularity in many areas. The advantage of these containers over tub

baskets, is that fruits are packed in

bulk without "facing," which reduces the cost of filling. Some reports indicate there is less bruising

m these containers than in tub baskets. The Spartan wirebound crate

was the first of this type of container tested. Although it was once used

extensively, its present use is limited. The Du-All, another type of

wirebound crate, has the sides and

bottom lined with chipboard. The

ends and a partial telescopic cover

are made of paraffin-impregnated

' For detailed instructions on grading and packing peaches, see U.S. DEPT. AGB.

1960. PREPARING PEACHES FOR MARKET. Mktg. Bul. 9, 21 pp., illUS.

fiberboard. At present, the Du-All

is second only to the tub basket in

popularity as a peach-shipping container.

Fiberboard cartons with telescopic lids also have been extensively

and, in some areas, successfully tested. Most of these cont<ainers however, will not withstand hydrocooling. To eliminate the effects of wetting the fiberboard cartons currently

in use, many growers are hydrocooling the fruit in field boxes or in bulk

hydrocoolers before packing in shipping containers.

The use of paper or plastic cup

trays in fiberboard cartons is becoming increasingly popular for shipping large and fancy peaches.

These trays also reduce transit

bruising of softer fruit harvested at

a riper stage. Such fruit requires

precooling before packing in these

trays.''

At the high outdoor temperatures

that prevail during the peach-marketing season, picked fruit ripens

rapidly. Peaches picked at the

shipping stage of maturity become

eating ripe in 2 to 4 days at temperatures of 70° to 80° F. Kipening

proceeds about half as fast at 60°

as it does at 70° to 80° and about

half as fast at 50° as at 60°._ At 60°

and above, peaches ripen with good

aroma and flavor. If they are held

at 50° until ripe, the flavor is undesirable. At 40°, ripening proceeds about half as fast as at 50°,

and the peaches usually break down

internally before they become fully

ripe. Temperatures of 36° and 32

hold ripening practically at a standstill. After being exposed no longer

than 1 week to 50° temperature or

lower, peaches will ripen normally

at room temperature. After exposure for 10 days or longer to temperatures between 36° and 50 ,

peaches are likely to break down internally or to become mealy or onflavored if ripened at room teraper46
ature. Peaches can be held somewhat longer at 32° than at 36° to

50° without losing the capacity to

ripen normally when exposed to

ripening temperatures.

Peaclies are sometimes stored for

short periods to extend the marketing season and the commercial canning season. Fruit that is to be

stored should be cooled to a temperature of 31° or 32° F. promptly after

picking. Even under the most favorable conditions, peaches cannot

usually be stored longer than 2 to

3 weeks. Loss of the capacity of

stored peaches to ripen with good

dessert, quality and without breakdown cannot be readily determined

by casual inspection. The proper

time for bringing fruit out of storage and marketing it must be determined by experience with the variety. The storage life of J. H. Hale

peaches cooled promptly to a temperature tetween 31° and 32° may

be 3 or 4 weeks. That of Elberta,

Redhaven, and Golden Jubilee

peaches similarly cooled is 2 to 3

weeks.

Peaches freeze at about 30° F.

To allow for cold spots in the storage room and to provide a margin

of safety, peaches should not be

held in a room with an air temperature lower than 31° or 32°.

Because of the influence of temperature on ripening, peaches

should be moved to market rapidly

and under the coolest possible conditions. However, if they can be

delivered to market the morning

after they are picked, an unrefrigerated track is usually satisfactory.

Nearly all peaches harvested in the

Southeast and a great many in the

East and Middle West are now being hydrocooled before shipping.

Most peacli hydrocoolers are ice refrigerated, but the use of mechanical refrigeration is steadily increasing. The hydrocoolers ai-e installed

in the packinghouses as part, of the

¡jacking lines. Peach containers

are moved through the hydrocooler

under a flood of cold water (fig. 27).

The water should be maintained as

close to 32° as possible by proper

refrigeration. The rate of cooling

is affected by size and initial temperature of the fruit, by water

rloURE 27.—Typical peach hydrocooler in operation. (Courtesy of Food Machinery and

Chemical Corporation, Lakeland, Fla.)

47
temperature, and by time in the

cooler (controlled by varying the

com^eyor speed). Fruit temperatures can be reduced 20° to 30"" in

10 to 15 minutes. Wooden containers, such as wirebound crates and

baskets, are satisfactory for hydrocooling. But, as previously stated,

fiberboard cartons must be treated

or made of moisture-resistant materials to successfully withstand

wetting. Bulk hydrocoolers have

recently become available and are

being used to a limited extent, usually when peaches are to be packed

in the plastic cup trays or in fiberboard boxes.

Ice-refrigerated trucks or trailers

used for shipping peaches should be

equipped with proper air circulating fans or blowers. They should

have floor racks or stripping, and

all doors and vent covers should be

fitted tightly to minimize air leakage. Floors should be cleaned before loading. From 1 to 3 inches

of insulation is necessary. Enough

ice must be maintained in the bunkers to insure a temperature of 50°

F. or lower during transit. Fanequipped refrigerator cars should

be used and moved with the fans in

operation. ^Vlien a car is held on

track at destination for more than a

few hours, electric hold motors

should be attached to operate the

fans. Fan operation will maintain

more uniform load temperatures

and prevent undue ripening that

would occur in warm spots in the

load.

Mechanically refrigerated cars

and trucks are more desirable because they provide better control of

transit temperatures than do icerefrigerated vehicles.

In areas where hydrocooling is

not available, peaches should be

room precooled or precooled in icerefrigerated cars by operating car

fans with special electric precooling

motors or by the use of portable

precooling fans installed temporarily in the top bunker openings. Up

48

to 4 percent of salt should be added

to the ice to increase the cooling

rate. Such car precooling may be

done to advantage only if facilities

are available for replenishing the

ice in the bunkers promptly after

precooling, in order to maintain

during transit the low temperatures

established by the precooling.

Portable, mechanically refrigerated

units may also be used for precooling in cars or trucks. By these different methods, it is possible to

lower the average temperature of a

load of peaches about 20'' to 25° F.

in 5 or 6 hours.

Warm peaches loaded in mechanically refrigerated cars or in the

new thermostatically controlled

ice-refrigerated fan cars with continuously running, power-operated

fans may be cooled m transit without being held on track at loading

point for precooling, as is required

with conventional ice bunker fan

cars. Since mechanical cars are

usually not designed for rapid cooling, it takes from 18 to 36 hours to

reduce the fruit temperature to 50°

F. However, with proper thermostat setting, lower temperatures can

eventually be reached and maintained in transit in these cars than

can be obtained in the conventional

iced car.

In most peach-producing regions,

the development of decay during

marketing is a serious problem, particularly in seasons when rainfall

and humidity are high at or near

the harv^est period. The two principal decays of peaches are brown

rot and rhizopus rot (fig. 28). Both

decays are caused by fungi. BroAvn

rot occurs chiefly in the orchard,

and how much brown rot occurs in

peaches after harvest depends

largely on how well the rot has been

controlled in the orchard by spraying and sanitary measures. Indications also are that, unless the hydrocooler and hydrocooling water are

kept clean, the hydrocooling operation may serve as a method of inoculating peaches with spores of the
FIGURE 28.—Postharvest decays of peaches. Left, brown rot; and right, rhizopus rot.

brown rot and rhizopus rot organism. Rliizopus rot usually occurs during harvest, in packinghouses, or in transit. At temperatures of 60° to 80° F., both brown

rot and rhizopus rot develop and

spread rapidly. Both can usually

be checked by cooling the peaches as

soon as possible after harvest and

keeping them at temperatures below

50° throughout the marketing period. Since ripening also is retarded by these temperatures, there

. must be some point during market-

: ing or after the peaches reach the

consumer when they must be ex-

. posed to temperatures high enough

to ripen them. At such tempera-

. tures, decay will develop rapidly.

Therefore, although low temperatures during transit and marketing

¡may make it possible to market the

fruit before decay becomes serious,

/hey do not reduce the total amount

01 decay that can develop in the

rniit by the time it has been ripened

enough to eat. For this reason,

'Other means of controlling decay are

necessary.

During hydrocooling, the ice-

'«'ater treatment by itself only temporarily slows the growth of decayProducing organisms. To prevent

the increase of these organisms in

the hydrocooling water, chlorine in

the form of calcium or sodium

hypochlorite at concentrations of

100 to 120 parts per million is usually added to the water. However,

this chemical is not very effective in

preventing the development of

brown rot originating from orchard

infection. The effectiveness of this

chemical in preventing a buildup of

organisms in hydrocooling water is

greatly reduced if the hydrocooler

and the hydrocooling water are

dirty. Other chemicals that effectively reduce these rots have been

found, but no satisfactory method of

applying them commercially has

been developed.

Recent tests have shown that both

brown rot and rhizopus rot were

effectively reduced when peaches

were treated in water at 130° F. for

2 to 3 minutes. The use of hot

water to reduce these decays, however, is still in the experimental

stage, although it was used successfully in one packinghouse in 1963

and 1964. The temperature of the

water and the length of exposure are

critical. A long exposure or water

temperature much above 130° may

49
seriously injure the fruit. Skin

mottling of some varieties occurred

even with the recommended treatment. Therefore, low temperatures

are still the most eiïective means

presently available for delaying

the development of decay during

marketing.

DISEASES CAUSED BY FUNGI AND BACTERIA

The principal fungus and bacterial diseases of peaches grown east

of the Rocky Mountains are brown

rot, scab, and bacterial spot. These

three widely distributed diseases

frequently cause heavy losses to

peach growers, shippers, and consumers. Other fungus and bacterial

diseases of peaches in this region include leaf curl, rust, constriction,

crown gall, powdery mildew, root

rots of various types, and dieback.^

Brown Rot

Brown rot, the common rot of

peaches, starts frequently at an insect puncture as a tiny, circular,

brown spot on green or ripening

fruit. It is sometimes referred to as

gray mold and ripe rot. The surface area afi'ected enlarges rapidly.

The rot penetrates deeply in the

flesh of the peach. Although the

entire peach becomes rotted, it

usually retains its form and remains

attached to the tree for some time.

It then either falls or, if retained on

the tree, gradually shrinks and dries

into a hard brown to black mummy.

Masses of ash-colored spores are

produced on the rotted surface; this

gives the peach a brownish-gray appearance (fig. 29). These spores,

known as conidia, may be carried by

insects, birds, wind, or splashing

raindrops—or even by man—to

nearby healthy peaches, which they

infect.

FIGURE 29.—Peaches covered with spores of the brown rot fungus. The infection spreads to

the twis from the blighted blossom still attached to it, and to the fruit from the twig.

®This section was prepnred by H. L. Keil, Crops Research Division. . .

" The organisms causing diseases mentioned are as follows : Brown rot, lío«*'»'*

fnicticola (Wint.) Honey; scab, Cadosporium carpophilum Thuem. ; bacterial spotXanthomonas pruni (E.F. Sm.) Dows. ; leaf curl, Taphrina deformans (Berk.) Tul.;

rust, Tra>izschc1ia discolor (Fekl.) Tranz. & Litv. ; constriction Fusieocaim amygdali

Del.; crown gall, Agrohacterium tumefaciens (E.F. Sm. & Towns.) Conn.; powdery

mildew, Podosphaera owyacanthae (DC.) DBy, and Sphaerotheca pannosa Wallr. ex

Lev; root rots, Armillaria mélica Vahl ex Fr. and allied fungi. faUa leucostoma

Pers. ex. Fr., Polyporus palustris Berk. & Curt, and Stereum compUcatum (Fr.) Fr.,

and other fungi are commonly associated with dieback.

50
If peach mummies are allowed to

remain on the tree, the fungus maygrow into the twigs and cause

cankers, which may girdle and kill

the twigs. In the South, mummies

that remain on the trees rarely early the fungus through the winter.

In the North, however, mummies

left on the trees over winter often

produce numerous fungus spores

the following spring (fig. 30).

FIGURE 30.—Peach mummies producing

spores (conidia) oF the brown rot fungus.

These spores may be carried to

peach blossoms and may infect

them. This produces the phase of

the disease known as blossom blight.

Mummies clinging to the tree should

be removed and destroyed in the fall

or winter. If mummies are allowed

to accumulate under the trees and

become partly buried, they frequently produce goblet-shaped

fruiting bodies (fig. 31) known as

apothecia, which shoot spores of another kind (ascospores) in the air.

These spores, like the conidia, may

: infect blossoms.

Only occasionally does the brown

' rot fimgus destroy enough blossoms

1 m a peach orchard to thin the crop

• too much. But even a scattering of

blighted blossoms through the trees

seriously threatens the crop's safety,

ihe fungus may attack any part of

the blossom and cause it to turn

gray or light brown. The blossom

IS soon covered with the gray spores

ot the fungus, if wet weather prevails. From the infected blossom,

the fungus may penetrate the twig,

Kill twig tissues, and produce a

canker. Gum oozes from the twig

canker and causes the blighted blosFIGURE 31.—Goblet-shaped fruiting bodies

(apothecia) developing from partly buried

peach mummy.

som to adhere to the twig (fig.

32). The blighted blossom produces

masses of conidia during the current growing season and sometimes

even the following season. Thus, it

serves as a source of infection to the

ripening fruit.

Bro^vn rot may be controlled by

removing rotted fruit from the trees

and by removing mummies from

the ground or by cultivating underneath the tree to prevent the brown

rot fungus from fruiting on old

mummies left on the ground. The

trees should be properly pruned so

that they can be sprayed thoroughly. The fruit should be

thinned to reduce spread of the disease from infected to healthy

peaches. Insects such as the plum

curculio and the oriental fruit moth,

which puncture fruits and provide

entrance for brown rot spores,

should be controlled. The fruit

should be sprayed or dusted at regular intervals during the season.

51
FIGURE 32.—Gum oozing from brown rot

twig canker.

The best way to control brown rot

is by spraying or dusting.

Until a few years ago, sulfur was

the most widely recommended chemical for controlling brown rot. Recently, however, sulfur has been

partly replaced by organic chemicals such as dicWone and captan.

Dichlone (50-percent wettable powder) applied during the early bloom

stage at one-fourth and one-half

pound per 100 gallons of water effectively reduces blossom blight infection and the resulting twig

cankers. Dichlone, however, should

not be used following bloom because

it may injure the fruit. Captan,

although somewhat more expensive

than sulfur, has proved less injurious and is more effective in controlling the disease. The materials,

concentrations, and number of applications recommended vary among

different localities. Growers should

consult their State agricultural colleges for local recommendations.

In general, sulfur (6 pounds per

100 gallons of water) or captan (2

pounds per 100 gallons of water)

should be sprayed or dusted five to

eight times a season, depending on

the variety and on the weather, at

the following intervals : (1) During

pink bud before the blossoms open ;.

(2) at blossom time; (3) -wheni

three-fourths of the shucks have

dropped; (4) 10 days after shuck

spray ; (5) 10 days after the fourth -

application; (6) 2 weeks after the

fifth application; (7) 2 weeks after'

the sixth application; and (8) 2to3

weeks after the seventh application.

Sprays or dusts should be applied

frequently enough after the fifth

application to maintain adequate^;

protection against brown rot..'

Dusts are sometimes used just before harvest because they do not

leave an objectionable deposit,;

which sprays sometimes do. Eecently, growers have successfullystored peaches longer by dippingharvested fruit in a water-captan

suspension.

Tests have shown that brown rot

is not so much of a problem if the

plum curculio and oriental fruit

moth are kept under control. (See

section on "Peach Insects," p. 67.)

Scab

Scab, known also as black spot or

freckles, is a fungus disease of

peaches in which circular sjDots one--,

sixteenth to one-eighth inch in

diameter appear on the fruit usually

near the stem end of the exposed,

surface (fig. 33). These spots are

faintly green at first but soon be-^

come olive green to black, with welldefined margins. When numerous,,

the spots run together and form a

large, black, scablike area involving

as much as half the surface ot the

peach. The scabby area frequently

splits open ; this exposes the flesn,

which may then be infected by

52
FIGURE 33.—Scab spots on peaches, showins til« cracking that often develops when

the spots are numerous.

spores of the brown rot fungus or

rhizopus rot fungus. Where scab

infections are numerous, tlie fruit is

liliely to be so stunted and misshapen that it cannot be used.

The scab fungus attacks tender

green shoots of the current season,

producing small, brown, oval cankers that frequently have purplish

borders. These cankers are seldom

more than one-eighth inch long, and

they extend only slightly below the

surface. They rarely cause serious

weakening of twigs, but the fungus

in them may remain alive durmg

the winter and produce spores the

followmg spring that may infect

the new crop of fruit. Lesions,

which at first may be pale green and

eventually become dark green, may

also be found on the under surfaces

of leaves. Only in extremely severe

" cases does defoliation occur.

Scab can readily be controlled by

applying sulfur as either a spray or

a dust. The spray must De applied 2 weeks after the shucks have

dropped from the peaches and again

2 weeks later. Because scab spots

have not appeared on the fruit,

growers may think their crops are

safe from the disease. This is not

always true, because infections occur early in the season and the fungus grows so slowly that spots are

not visible until 40 to 60 days after

infection. When the spots do appear, it is usually too late for spraying or dusting.

Captan will control scab, but it is

not so effective as sulfur, especially

if used at concentrations of less

than 2 pounds per 100 gallons of

water. For this reason, sulfur

should be used when feasible.

Bacterial Spot

Bacterial spot, sometimes called

bacteriosis, bacterial shot hole, or

just shot hole, results from entrance

of a certain kind of bacteria into

uninjured tissues of leaves, twigs,

and fruit. On leaves, the first sign

of the disease is the appearance of

small, water-soaked areas that develop into purple or purplish-brown

spots (fig. 34), which are generally

angular in shape. The individual

spots are small at first, but they may

run together. Eventually, the affected tissues die and separate from

the healthy tissues, producing a

characteristic ragged, shot-hole appearance—hence the name "shot

hole." When many leaves are affected, especially on weak trees, premature leaf fall often results. The

disease is first visible on the fruit as

tiny, watery-looking, slightly

sunken spots. As the peach grows,

cracks and fissures of various sizes

develop and mar the appearance of

the fruit (fig. 54:, O). The cracking

around the spots of dead tissue

makes the fruit unmarketable and

frequently pennits the entrance of

brown rot or other fruit rot fungi.

Cankers are formed on the twigs

at various times during the growing

season. Some develop on green

shoots late in summer ("summer

cankers"), usually after foliage infection has become established.

Some develop on young, succulent

twigs in the spring ("spring cankers"), about the time the first leaves

appear. Bacteria responsible for

initial infection in the spring are

believed to originate from spring

rather than summer cankers.

Bacterial spot is present in all

States east of the Rocky Mountains

where peaches and plums are grown.

It causes serious annual losses,

chiefly where soils are light and low

53
B

FIGURE 34.—Symptoms of bacterial spot {A) on peach leaf, (B) on young peach shoots,

and (C) on mature J. H. Hale peaches.

54
in fertility. Although as much as

35 percent of the fruit of susceptible

varieties may be discarded because

of bacterial spot, the greatest loss is

due to devitalization of the tree resulting from defoliation. Vigorous

trees are less susceptible to the disease than are neglected trees.

Proper pruning, cultivating, fertilizing, and other good orchard-management practices are recommended

as control measures. But these

alone will not control severe bacterial spot infection, especially

where soil improvement is difficult.

Removing sources of overwintering

infections has not as yet been successful.

Bacterial spot has been held in

check in some areas by a series of

spray applications at 5- to 7-day intervals, starting at petal fall.

However, when the disease is severe

in other areas, the best materials

available have been only about 50

percent effective. More effective

materials than those now used are

needed.

Many sprays for controlling bacterial spot have been tested over the

past 30 years, but none can be conI sidered successful. The most satisI factory combination used today is

i the zinc-lime spray. The formula

! recommended is :

'Zinc sulfate (monohydrate) ^__. 5 pounds.

Hydrated lime 8 poundiS.

Water 100 gallons.

A monohydrate zinc sulfate (ZnSO4.H2O) containing 36 percent

zinc can be obtained through wholesalers and distributors who handle

spray materials. This material

should be stored in a dry place and

kept well covered so that it cannot

absorb moisture from the air and

become lumpy. The hydrated lime

should be fresh and of high quality.

The grade known in the trade as

chemical or spray is especially

recommended.

The spray should be prepared as

tollows: Fill the tank three-fourths

full of water. Start the engine and

slowly sift the zinc sulfate into th^

water while the agitator is moving.

If the zinc sulfate is not caked, it

will dissolve in less than 5 minutes.

After the zinc sulfate has dissolved,

slowly add the hydrated lime and

continue agitating while the tank

fills with water. If other fungicides and insecticides are used in

combination with zinc sulfate, they

should be added at this time. Captan should not be used with strongly

alkaline materials, such as hydrated

lime.

The zinc-lime spray will not control scab and brown rot. Sulfur

sprays, which are commonly used

on peaches to control bacterial spot,

may safely be applied to peach trees

in mixture with the zinc-lime spray.

To reduce bacterial spot, some investigators have suggested the use

of Bordeaux mixture spray (copper

sulfate plus hydrated lime in water)

applied either in the fall when the

leaves are ready to drop or in the

spring before the buds open. Because of its tendency to burn

peaches, copper should never be applied during the growing season.

If you wish to try Bordeaux mixture, do so only on recommendation

of your county agent or State agricultural extension scientists.

Leaf Curl

Leaf curl, often referred to as

"curl," "curl leaf," or "leaf blister,"

is an economically important disease occurring in all peach-growing

regions east of the Rocky Mountains. It is due to a fungus that

causes the early appearing peach

leaves to acquire a red to purplish

tint, which makes them conspicuous. These leaves become thickened, blistered, and distorted ; turn

reddish yellow or yellowish gray;

and later turn brown and drop. The

actual time of leaf fall depends on

the prevailing weather conditions.

Dry, hot weather usually hastens

55
leaf fall. The spores of the fungus

overwinter on the twigs and buds

of the peach tree, germinate, and infect the young leaves as they begin

to develop in the spring.

If only a small percentage of the

leaves are affected, the fruit set will

not be materially reduced and the

trees will not be seriously injured.

But if the number of affected leaves

is large enough to cause hea\^ defoliation at or near blooming time,

the disease may prevent fruit set

and devitalize the tree so that it becomes subject to winter injury and

attacks by other disease-producing

organisms.

Peach leaf curl can be controlled

by a single application of limesulfur solution, Bordeaux mixture,

ferbam, or dichlone made in the fall

after the trees shed their leaves;

during the winter w^hen the temperature is above freezing; or in the

spring before the buds begin to

swell. If application is delayed until after the leaves start to grow,

the disease will not be successfully

controlled and some materials applied at the suggested concentrations niay seriously injure the trees.

A lime-sulfur solution usually

gives satisfactory control when

used at the rate of 4 to 6 gallons per

100 gallons of w^ater. However,

when leaf curl is severe, somewhat

higher rates may be required. A

6-6-100 Bordeaux mixture (6

pounds of copper sulfate plus 6

poimds of hydrated lime in 100 gallons of water), fer^bam at the rate

of 2 pounds per 100 gallons, or dichlone (50 percent w^ettable powder)

at the rate of 1 pound per 100 gallons of water will also give satisfactory control of peach leaf curl if

applied according to directions.

All buds on the tree are subject to

infection and must, for complete

protection, be thoroughly covered

with the spray.

Bordeaux mixture may be used in

combination with an oil emulsion in

the dormant application to control

56

certain insects. The oil should be

added after the Bordeaux mixture

is placed in the spray tank.

Rust

Rust is a disease that appears toward the end of the growing season.

It usually affects the peach leaves;

but sometimes, under certain climatic conditions, it appears on twigs,

bark, and fruit. This disease is

found most commonly in the

w^armer sections of the stone fruit;

areas. Numerous pale, yellowish:

spots that later become bright yellow^ are evident on the leaf. Directly underneath these spots on the ;

lower leaf surface, powdery, cinnamon-brown spore masses develop.

In some seasons, rust infections be-^

come so numerous that they cause

premature leaf fall, which weakensi

the tree. At present, no measures

for controlling this disease are prac--

ticed east of the Rocky Mountains.,

ConstricMon

Constriction, sometimes referred.

to as Fusicoccum canker or peach

canker, is a fungus disease that has.

become economically important the

past two decades in the North At-.

lantic and Middle Atlantic States.^.

This disease affects twigs, blossoms..^

leaves, and fruit. Dark-brown can-;

kers, which later become grayish

tan, appear at the nodes of the cur-,

rent season's twigs. These cankers ^

often girdle the twig, make it wilt.

and eventually kill the affected;^

branch. Among the varieties se-,;

verely affected by the disease an ;

Golden Jubilee, Raritan Rose, Cardinal, Jerseyland, Triogem, J. H

Hale, and Redhaven. Recent stud;^

ies have been made in New Jersej '

on control of late season infectior i

by postharvest applications of mag

nesium arsenat^ and a certain or ^^i

ganic mercury compound. Furthei ;^

tests are necessary, however, befon ;

these materials can be recommendec rr

for use by peach growers. ;
Crown Gall

Crown gall is a bacterial disease

characterized by formation of swellings or galls on the trunks (usually

at the crown) and roots of the trees.

This disease, although prevalent

and severe in some sections of the

Southern States, may be found in

all peach-growing areas east of the

Rocky Mountains. In many cases,

the disease has been traced back to

the planting of infected nursery

trees. Nursery trees showing crown

gall should not be planted. They

will not grow well or mature, and

bacteria are likely to spread to other

trees. Removing the galls does not

free the tree of infection, and little

can be done to control the disease

once it becomes established in an

orchard. Considerable research is

being done to find a control for the

disease in the nursery ; but no practical, satisfactory control has yet

been developed.

Powdery Mildew

Powdery mildew, a fungus disease, was seldom a serious problem

in eastern commercial peach or-

^chards until use of organic chemical

sprays replaced use of sulfur sprays.

When sulfur is used, powdery mildew occurs infrequently and is of no

'^^^omic importance. However,

about 2 years after the organic com-

' pounds are used, powdery milde^v

i^ay often become prevalent and

. cause serious damage. The powdery

mildew fungus attacks leaves, young

^^oots, and fruit. The leaves may

:^ spotted with white to gray

patches or may be entirely covered

Jy a white, powdery layer of the

^gus. The fungus may extend

^ver the entire terminal portion of

tne growmg shoot and may sometiines kill it. Small, white round

spots first appear on the fruit.

I^ese spots may increase in size

^1^11 a large portion or the whole

surlace of the fruit is involved.

^^^its so attacked may turn a dull

reddish to pinkish color, and may

later turn brown. "Where powdery

mildew becomes serious, sulfur

spray or organic compound sprays

that include a small amoimt of sulfur should be^ used.

Fungus Root Rots

Root rots due to several different

fungi may, at times, cause the death

of peach trees. The first evidence

of root rot may be the appearance of

small, yello^vish leaves that cover

the entire tree or that are confined

to one or two branches. The entire

tree or the affected branches may die

by the end of the summer; or they

may survive the Avinter and die the

following year. Once a tree is affected, there is little hope of sa\âng

it. Research now being conducted

with certain soil fumigants may

help solve this problem. Growlers

finding an appreciable number of

trees affected with root rot should

consult their State agricultural extension service.

Dieback

"Dieback" is a general name given

to a number of conditions that cause

the death of peach twdgs and

branches. Dieback may be caused

by various types of fungi and also

by some bacterial organisms. These

organisms frequently infect the

buds or wounds and produce cankers that usually enlarge slowly,

sometimes girdling the affected limb

or twig. When this occurs during

the growling season, the leaves take

on a yellowish color and then suddenly wilt and die. Sometimes a

gumlike substance is produced on

the surface of the canker. In many

cases, infection has been associated

with spray injury, frost damage,

and improperly healed pruning

wounds. Insofar as possible, practices should be followed that produce the maximum quantity of

marketable fruit with the least

damage to the tree.

57
DISEASES CAUSED BY VIRUSES

Virus diseases were first associated with peach culture in the 19th

century. Stories of the devastation

and losses resulting from epidemics

of peach yellows in Northeastern

United States during the ISOO^s

serve as reminders that virus diseases can be serious if they are left

uncontrolled. Little peach, another

virus disease, which is thoug'ht to be

caused by a strain of the yellows

virus, became damaging in the same

geographic area as did yellows in

the late 1800's, and now causes more

losses than do yellows. In Southeastern United States, peach rosette

and phony peach disease, both

caused by viruses, have been common since the early 1900's and cause

serious crop losses. Within the past

30 years, the following additional

virus diseases affecting peaches have

appeared in Northeastern United

States: Red suture, X-disease, rosette mosaic, necrotic leaf spot, ring

spot, and line pattern. Peach mosaic and asteroid spot are virus diseases that occur in Southwestern

United States as far east as eastern

Texas, southern Oklahoma, and

western Arkansas.

For the purpose of this discussion, a virus may be considered as an

extremely small organism, too small

to be seen through the ordinary

compound microscope, which lives

and multiplies as a parasite in livmg

tissue. Virus diseases of plants are

commonly spread in one of several

ways—through juice, by infected

propagation material, and occasionally through seeds from infected plants. In nature, they are

most commonly spread by insects

and mites. These insects suck juice

from infected plants and lose some

of it while feeding on healthy

plants, thereby infecting them.

None of the viruses affecting peach

trees is known to have been transmitted mechanically from peach to

'" This section was prepared by L. C. Cochran Crops Research Division.

peach with infected juice. Only

one, ring spot, has been found transmissible through seeds. Ring spot

passes through some of the seeds of

mazzard and mahaleb cherries and

occasionally through peach seeds.

It is highly improbable that any,

of these viruses can be spread by

cultivation procedures, such as

pruning, spraying, thinning, or tillage. They can be spread mto new

areas by use of infected nursery

stock. Within orchards they can be

spread by insects and through use of

infected propagation material.

Peach yellow bud mosaic, known to

occur only in California, and peach

rosette mosaic, which occurs in

Michigan, in New York, and possibly in other Eastern States, have

been retained in the soil by nema-i

tode vectors where diseased trees are|

removed. Thus, these diseasesi

could be spread by movement of in-^

fested soil. ii

Peach Yellows

The symptoms of peach yellowsi

are premature ripening of fruit; in-|

ward rolling, drooping leaves, palef

green to yellow in color; and de-f

velopment of small, clustered shootsi

with yellow leaves along the trunkÉ

and main branches of the tree (figs.|

35 and 36). Fruit on affected trees^

ripens from a few days to 3 weeksk

earlier than normal, lacks sweet-ji

ness, and is bitter. The peel on af-'j

fected fruit is commonly spotted

with red and purple, and on normally red varieties it may be solid

purple. Ked streaks of different

lengths extend from the pit toward

the peel, and in red varieties the

tissue around the pit is deep red.

On young trees and vigorous

older trees affected with peach yellows, buds formed in the summer

do not remain dormant but put out

small, yellowish leaves the same

58
nüURE 35.—'The small, willowy growth from main limbs of this tree is a symptom of peach

yellows. This growth is known as wire shoots. (Courtesy of Illinois Natural History

survey.)

i season. In advanced cases, the ends

of twigs and branches die ; and düstere of small shoots bearing small,

pale-green to yellow leaves grow

; m the trunk and main branches.

'^ûese are known as wire shoots.

>5ome varieties produce more wire

'loots than others. Affected trees

usually die in 2 to 6 years.

Plum trees, both cultivated and

wild, have been fomad to carry the

yellows virus; but most plum species

are not injured by it and do not

show any easily recognized symptoms. The disease is spread by the

plum leafhopper (Macropsù triviaculata), which prefers to feed on

plums and migrates from them to

59
FIGURE 36.—Closeup view of willowy growth arising from a main limb of a peach tree affected

with yellows. Note slenderness of twigs,- light color, small size, and abundance °''*°|y"|;

and dark spots on leaves. An almost normal water sprout is seen at the base of the li"!

at the right. (Courtesy of Illinois Natural History Survey.)

peaches. In localities where the disease has become widespread,

peaches should not \ye grown within

1 mile of plums.

Yellows-affected trees should be

removed from the orchard as soon

as the disease is recognized. If an

infected tree is left standing m an

orchard, the disease spreads rapidly to neighboring trees. Some

States have laws prohibiting sale

of yellows-affected fruit and re60
quiring that yellows-affected trees

be destroyed. Care should be taken

to obtain peach budwood from

known yellows-free sources and to

grow nursery stock apart from any

natural hosts of the yellows virus.

Plum trees considered as a source

of material for budding or as rootstocks should be checked for yellows before they are used. The yellows virus can be killed in peach

budwood or in nursery trees with

heat, but there is no known method

of curing infected orchard trees.

Little Peach

Some symptoms of the little peach

disease are enough like those of yellows to suggest that little peach is

caused by a strain of the yellows virus. Trees affected with little

peach, like those with yellows,

have a droopy appearance. In late

stages of the disease, the leaves turn

pale green to yellowish. Little

peach is transmitted by the same

insect as is yellows. The little

peach virus is killed by heat at the

same temperature that inactivates

the yellows virus. Little peach differs from yellows in that fruit on

affected trees fails to ripen, or ripens late instead of prematurely,

and there is less yellowing of foliage m the early stages of the disease.

Irees affected with little peach appear stunted and compact or

bushy, because there are more

^ves on the short spurs along

fie mam branches. They do not

produce the slender yellow shoots

(wire shoots) on the trunk and

inam branches that are characteristic of yellows-affected trees. Leaves

on trees in advanced stages of little peach may be curled by recurv-

^g of the midrib toward the

twig, but the halves of the leaves

are not as closely folded as they are

with yellows. Fruit is usually

small and has a poor flavor. It

does not have the red color on the

peel or in the flesh that is characteristic of yellows.

Little peach, like yellows, affects

clitierent species and varieties of

plums. Some plums show a few

symptoms, but some do not.

The control for little peach is

the same as for yellows.

Red Suture

Red suture, also, belongs to

the yellows group. It has occurred

m Michigan, Ohio, and Maryland.

The leaf and tree symptoms of

red suture are more nearly like

those of little peach than like

those of yellows. Leaves on affected

trees are recurved, terminal growth

is shorter than normal, and an abnomial number of short shoots

bearing clusters of leaves arise

along the main branches. In

advanced cases of red suture, there

is some tAvisting of leaves. Most

leaves are lighter than normal in

color, and the centers of trees appear open. As with yellows, the

fruits on affected trees ripen several days early, the suture ripening first. Frequently, the suture is

unevenly swollen. On red fruits,

the tops of the ridges and bumps

have dark red or purple blotches.

The flesh of the early ripening portion is usually soft and watery. The

affected fruits are usually low in

sweetness and insipid in flavor.

Little is known of the host range

of red suture. InsuiRcient tests

have been made to determine

whether the leafhopper that spreads

peach yellows can spread red

suture.

The control for red suture is the

same as for yellows, but is less efficient because it is harder to recognize diseased trees, especially in

the early stages. Trees may be diseased for a year or longer before

they develop recognizable symptoms. During that time they serve

as a reservoir from which the disease can be spread.

In the infected area, red suture

is becoming more serious.

61
X-Disease

The X-clisease was named for x^

the symbol of an unknown quantity,

because of its peculiar symptoms.

Diseased peach trees appear normal

until midsummer (the date varies

with locality). Then, within a few

days, leaves on affected twigs, starting near the base of the current season's shoots, become progressively

pale, commonly roll upward, become brittle, and develop irregular

yellow and red spots. Some of

these spots shrink and fall out.

The number of leaves affected and

the size of spots on individual leaves

increase rapidly, causing a;ffected

shoots to become highly colored.

Leaves on affected twigs are usually

shed progressively from the base to

the tip. Tip leaves seldom become

affected, and they remain on the

tree. During hot weather, leaves

often drop before the spots are well

formed. Fruits on affected twigs

usually shrivel and fall soon after

leaf symptoms develop. Fruits on

twigs where leaf symptoms develop

late in the season may remain on the

trees. However, they ripen prematurely and are bitter, and their seeds

fail to develop.

Diseased twigs or branches, even

though they shed their leaves, do

not always die. If they survive,

they leaf out normally the following

spring; then the sequence of symptoms is repeated. The disease

usually begins on one or several

twigs and spreads irregularly

through the tree. If often takes several years to affect most of the tree.

Unlike some of the other viruses

affecting peaches, the virus causing X-disease seldom becomes distributed through the whole tree.

Normal-appearmg twigs on diseased trees are free of the virus and

produce normal fruit. Affected

trees under 3 years of age frequently die; older trees^ although they

become unproductive, usually do

not die as a direct result of Xdisease.

62

Besides peaches, the X-disease

virus infects cultivated cherries

(both sweet and sour) and several

wild plum and cherry species. The

most commonly affected wild host is

the chokecherry {Prunus virginiana). This plant is widespread in

Northeastern United States and adjacent areas of Canada and forms

dense woodland and fence-row

thickets. The disease appears to

have spread rapidly in this host

from where it was first seen in New

England through New York, Ohio,

and Michigan and into Wisconsin,

Illinois, and Iowa. Diseased chokecherries prematurely develop varying degrees of autumnal yellow and

red foliage, beginning as early as

June. They usually die in 3 to 4

years.

X-disease is spread by the leafhopper Golladorms cUtellarms

( Say ). This leafiiopper lives principally on chokecherries but occasionally migrates to other nearby

plants. If it has fed first on diseased chokecherries, it can carry the

virus to peach and cherry trees.

Peach nursery plantings should be

at least 500 feet from chokecherries

and other wild cherry or plum species. Eradication of chokecherries

within 500 feet of peach orchards

will protect the trees from infection.

Chokecherries can be effectively

eradicated by spraying them with a

water solution of ammonium sulfamate when they are in full leaf.

The recommended strength is threefourths pound per gallon, and the

recommended rate of application is

2 gallons of spray per 100 square

feet. Sodium or calcium chlorate

at the same strength is also effective.

Atlacide, a proprietary material

containing chlorates, is less dangerous and is effective if used according

to the manufacturer's directions.

Brush killers such as 2,4,5-T in

kerosene, or diesel oil at the rate of

10 to 12 pounds per 100 gallons of

oil sprayed around the base of the

chokecherry in midsummer, has also
been effective. After the sprayer is

used, it must be washed thoroughly

(five or six times) witli a warm,

soapy, soda sohition in water.

Sodium and calcium chlorates

must be handled with care, since

they are flammable.

Phony Disease

Phony disease has caused serious

losses in Georgia and Alabama.

About 2 million phony-affected

peach trees have been removed from

orchards in Georgia alone since

1930.

Phony disease dwarfs peach trees

and causes them to be darker green

and more dense in appearance than

normal (fig. 37). The dense appearance is due to an abnormal

number of lateral twigs with shortened internodes and a closer spacing

FIGURE 37.—(A)Phony-affected Elberta peach tree at Fort Valley, Ga.; (B) normal Elberta

tree in the same orchard.

63
of fewer but flatter leaves on the

twigs. The symptoms are progressive. Diseased trees become noticeable in early summer when normal

trees outgrow them. By July, diseased trees are easily distinguished

fr,om normal trees. Fruit is smaller

on diseased trees than on normal

ones and becomes smaller each year

because of the disease. Phony disease does not kill peach trees, but

affected trees are weakened and are

more susceptible to winter injury

and other orchard troubles. Trees

that become diseased when young

never reach productive orchard size.

Phony disease affects all peach

varieties similarly. It is spread by

several species of large leafhoppers

commonly known as sharpshooters.

The insects prefer to feed directly in

the water-conducting tubes in

woody stems. Phony spreads

rapidly in some areas and increases

in rate in proportion to the age of

the trees and the number of diseased

trees present. The wild chicasaw

plum Prunus angustifolia Marsh.,

which occurs in thickets all through

Southern United States, has been

found naturally infected near

phony-affected peach orchards in

Georgia.

Phony-affected peach trees should

be destroyed promptly. Surveys

have shown that the disease spreads

less rapidly among the remaining

trees when diseased trees have been

removed. In infected areas, wild

plums should be eradicated from

the vicinity of peach orchards.

Quarantines covering the infected

area prohibit growing nursery stock

withm 1 mile of diseased trees.

Peach Rosette

Peach rosette is another virus disease affecting peaches in Southeastern United States, It kills rapidly

and has caused severe losses in areas

where diseased trees were left

standing.

Symptoms of peach rosette gen64

erally appear in spring or early

summer. The first formed leaves

turn yellow, and shoots fail to elongate. Leaves formed later are small

and, because of shortened stems,

grow into tight rosettes (fig. 38).

The older leaves turn yellow and

drop first. Trees affected throughout usually die before the end of the

growing season. Trees partly affected may live into the second year

but die by the end of that season.

The disease usually occurs in close

colonies and may spread rapidly.

The chickasaw plum occasionally

becomes naturally infected and

serves as a virus reservoir from

which the disease spreads to peach

trees. Symptoms on it are similar

to those on peaches.

Peach rosette can be effectively

controlled by prompt removal of

diseased trees in and near the orchard.

Peach Mosaic

Peach mosaic occurs in Southwestern United States as far east

as eastern Texas, in southern Oklahoma, in western Arkansas, and

in Mexico. It has caused serious

losses both directly by crop reduction and, indirectly, by necessitating removal of diseased trees.

As the name implies, the most

common and noticeable symptom of

peach mosaic disease is the mottled

pattern of yellow and green in the

leaves. All peach varieties are susceptible to infection, but some are

more seriously damaged than

others. Varieties such as J. H. Hale

(or its derivatives), Elberta, Rio

Oso Gem, and Fay Elberta are severely injured. But most clingstone

varieties endure the most severe

forms of the virus with only moderate damage. Newly infected trees

of the J. H. Hale variety are retarded in the spring and develop

small, narrow, deformed leaves

with various irregular, mottled patterns (fig. 39). As the season

progresses, the mottling becomes
FIGURE 38.—Orchard tree aífected with peach rosette and showing typically resetted foliage.

Such a tree usually dies before the beginning of the next season.

less distinct, but the trees are

dwarfed and the fruit is bumpy

and misshapen. Symptoms vary because of the different forms of the

virus, some of which are more damaging than others. Damage is most

severe in cool climates.

Peach mosaic virus is common in

certain wàld stone fruits, including

the chickasaw plum, wildgoose

plum {Prumi^ munsoniana Wight

& Hedr.), and American plum (P.

americaTia Marsh.), as well as in

certain cultivated stone fruits.

Some of these hosts act as symptomless carriers. The rate of spread is

more rapid in some areas than in

others. The natural vector of peach

mosaic is a microscopic eriophyid

mite, Eriophyes ¿nsidiositë Kiefer

and Wilson, which lives exclusively

within retarded buds and which is

removed by wind to healthy trees

as the buds open.

In areas where very susceptible

varieties are grown, losses from

peach mosaic can be reduced to less

than 1 percent per year by removing

diseased trees and excluding tolerant varieties in which symptoms

are absent and diagnosis is difficult.

In areas where the disease spreads

rapidly, wdiere wild hosts are prevalent, or where the cost of removing

65
FIGURE 39.—Leaves of J. H. Hale peach affected with peach mosaic. The symptoms vary

from marginal bands in the first leaf at the left to shot hole and velnlet clearing in the leaf at

the extreme right.

diseased trees is uneconomical, tolerant varieties can be grown. Since

orchards of Elberta and J. H. Hale

and other nontolerant varieties

malve up a large percentage of the

freestone acreage in the United

States, strong safeguards should be

maintained to prevent spread of the

peach mosaic disease to noninfected

areas. Infected areas are now under quarantine. The sale of peach

nursery stock grown within 1 mile

of infected trees or of budwood

taken from trees within 1 mile of

infected trees is prohibited.

Rosette Mosaic, Ring Spot, Necrotic

Leaf Spot, Line Pattern, and Asteroid Spot

Several virus diseases affecting

peaches in Eastern United States

cause only minor crop losses. The

most serious of these is rosette mosaic, which occurs principally in

Michigan and New York. This disease causes mottling, dwarfing, and

resetting of the foliage, and a corresponding reduction of tree vigor.

The causal virus sometimes remains

in the soil and can infect a new tree

set where a diseased tree was removed.

The ring spot virus retards spring

growth and causes light-colored and

necrotic ring patterns on leaves.

Sometimes ring spot kills and splits

peach tree bark. Symptoms of ring

spot are usually present only during

the first growing season after infection. Infected trees appear to recover, but they retain the virus

without visible symptoms in succeeding years. In the nursery, infected buds grafted on healthy

peach seedlings fail to grow. The

virus exists more commonly in

plums and cherries than in peaches.

Necrotic leaf spot differs from

ring spot in that it produces no

symptoms in the spring but produces dead spots on leaves each year

in midsummer.

Although line pattern is primarily a plum disease, peaches have

66
been infected with it through bv;dding; and obscure, mottled leaf patterns have resulted.

Asteroid spot in pe<aches is common in Texas and the Western

btates. It produces small, starshaped spots of varying size scattered over the leaves.

PEACH INSECTS

The common insect pests of

peaches grown east of the Rocky

Mountains are the plum curculio,

the peach tree borer, the lesser peach

tree borer, the San Jose scale, the

oriental fruit moth, and a group of

sucking bugs, including among others the tarnished plant bug and certain species of stinkbugs.^^

Plum Curculio

The plum curculio is a small,

humpbacked beetle with a brownish

snout, which hibernates in trash in

or near the orchard. Early in the

spring, the curculios move into the

trees. If they come from outside

the orchard, they appear first on

trees in the outer rows and later

move to other parts of the orchard.

They lay eggs in small peaches soon

after the fniits form. The larvae,

or grubs, feed within the fruit for

2 weeks or more ( fig. 40 ). The mature grubs leave the fruit and go

into the ground, where they complete their development and emerge

as adult beetles. In the South, a

second generation infests midseason

varieties such as Elberta.

Because the development of the

curculio varies according to seasonal

and local conditions, the control programs vary with the season and locality, usually, an insecticide is

applied three or four times during

the month following petal fall.

Where two generations occur in one

Í ^

FIGURE 40.—Curculio grub and its injury to

ripe peach.

season, one or two additional spray

applications are made, usually during the month before picking time.

Peach Tree Borer

The peach tree borer is a white

worm about 1 inch long that works

underneath the bark near the

ground line, often injuring the tree

seriously or even killing it. At maturity, the lar\'ae change to pupae,

then to adults, which are clearwinged moths. In the southern

part of the Gulf States, a few moths

appear as early as May or June ; but

heaviest emergence in the South occurs during August and September.

" More complete, general information on peach insects and their control is available

in U.S. DETT. AGR. 1963. INSECT PESTS OF THE PEACH EAST OF THE KOCKY MOUNTAINS.

Agr. Inf. Bui. 272, 32 pp. illus. More detailed information on various peach insects

and on new insecticides should be obtained from your local State agricultural college

or extension service or from your county agricultural agent or farm adviser.

The scientific names of the insect.s listed are as follows : Plum curculio. Conntrachelns nenuphar (Hbst.) ; peach tree borer, Sainiinoidca cxitiofia (Say) ; lesser

peach tree borer, Synanthedon pictipes (Grote & Robinson) ; San Jose scale, Aspidiotiis perniciosas Comst. ; oriental fruit moth, Grapholifha molesta (Busck) ; tarnished

plant bug, Lygus lineolaris' (P. de B.) ; stinkbugs, chiefly Euschistus spp.

67
In the North, most of the moths

emerge during July and August.

Egg laying begins shortly after

moths appear. Most eggs are

placed on the tree trunk but some are

placed on small branches of the tree

or on the soil or weeds nearby.

After the eggs hatch, the young

larvae move to the lower part of the

tree trunk and usually enter it at the

soil surface. Usually there is only

one generation a year.

Lesser Peach Tree Borer

The lesser peach tree borer is similar to the peach tree borer but

mainly attacks the trimk and limbs,

particularly in injured areas and in

crotches. It passes the winter as a

larva in injured areas on the tree.

It pupates early in the spring and

emerges as a clearwinged moth that

lays its eggs along the trunk and

limbs of the tree. One generation

occurs in the North, and two occur

in the South.

San Jose Scale

The San Jose scale is a tiny insect

that lives under a very small, inconspicuous, grayish, scalelike

covering. Small reddish discolorations are often found at the point

of feeding, particularly on new,

tender wood. Heavily infested

trees have a roughened, grayish appearance. Other signs of infestation are dead twigs and limbs, and

a lowering of the vitality of the

trees. A heavy, continuing infestation may kill the trees.

All stages of the scale are present

most of the year, but scales that are

partly grown sur^dve the winter

best. They complete their growth

in the spring. The insect remains

in one place except during the first

few hours of its life and during the

short time adult males are active.

The generations overlap ; there are

one or two generations a year in the

more northern fruit areas and three

or more farther south.

Oriental Fruit Moth

The larva of the oriental fruit

moth is a pinkish-whit^ worm with

a brown head. When fully grown,

it is about one-half inch long.

Early in the season, the larvae tunnel into new peach shoots (fig. 41),

causing them to wilt and dry up.

Later, usually near hangest, the

larvae bore into the fruit. Infestation of fruit is heaviest in midseason and in the later maturing peach

varieties. The insects pass the winter as full-grown larv^ae, or worms,

in cocoons in a protected place

on the tree or ground. Moths first

appear about the time peach trees

are in bloom. The females usually

lay their eggs on the leaves. The

larvae feed on twigs or in the fruit

until they are mature and then spin

cocoons in a protected place on the

tree or ground. Usually there are

four or five generations each year.

Sucking Bugs

The tarnished plant bug and several other species of sucking bugs

feed on peach blossoms and on

newly formed peaches and cause the

fruit to become seriously scarred

and distorted (fig. 42). These bugs

live and feed chiefly on weeds or

field crops in or near the orchard.

They suck on peaches for only a

short period in the spring. Where

it is consistent with good horticultural practice, eliminating weeds

and certain cover crops aids considerably in controlling them.

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FIGURE 41.—Oriental fruit moth injury to peach twiss.

69
/^Á

70

FIGURE 42.—Peach injury caused by suckins bugs.

U.S. GOVERNMENT PRINTING OFFICE: 1965 O—757-340