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APPLE YIELDS
CIRCULAR 122 MARCH 1958

AGRICULTURAL EXPERIMENT STATION of the ALABAMA POLYTECHNIC INSTITUTE
E. V. Smith, Director Auburn, Alabama

CONTENTS
Page
M ETHOD OF STUDY------------------------- --- 4

F IN D INGS - - - - - - - - - - - - - - -- - - - - - - - - - - - - - --

4

Yield Classes -- - - - - - - - - - -- - - - - - - - - - - - - - - - -- - - - - - - 4 Cultural Practices --- -- ---- ---- -- --- ---- --- --- 5 - 7

Nutritional Status--- --- -- --S oils -- - - - - - - - - - -- - - - - - - - - - -8

--- -- --- ---

Tree S pacin gs -- - - - - - - - - - -- - - - - --- - - - - - - - - - - - - - - -- - - 8 V arie tie s - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - 9 D iseases and Insects ---------------------RECOMMENDATIONS

---------- 10

FOR INCREASING PRODUCTION-----------11
----

Fertilizatio n -- - -- Disease and Insect

- - - - - -- - - - - - - -- - - - - - - - - - - - - - - - - 11

Control ---------------------------- 11
---- ---- ---- -- - -- -- -- 11

N ew Plantings--- -- --- --- - -----

FIRST PRINTING

5M,

MARCH

1958

4 9hctors w ffecnp

APPLE YIELDS
JACK L. TURNER, Assistant Horticulturist T. B. HAGLER, Associate Horticulturist

APPLE GROWING in Alabama is an old agricultural enterprise. Production is centered primarily in central and northern sections of the State. The apple-growing area is comprised largely of mountain chains that afford favorable conditions for fruit production. Nights are relatively cool during the growing season in this region that has elevations of 600 to 2,400 feet. Production is primarily for fresh market sales. Most varieties bloom reasonably early and mature a crop of fruit by mid- or late summer. There is much less competition for fresh market apples during this period, and prices are usually good for high-quality fruit. Apple production has contributed substantially to farm income in northern Alabama in past years, but recently yields of marketable fruits have decreased to the extent that this enterprise now contributes little income except in a few counties. In 1945, Alabama produced 498,039 bushels of apples with market value of $1,146,341.1 By 1954 production dropped to 166,448 bushels with a market value of $382,835. Tree population in 1954 was 167,794 bearing trees and 57,927 nonbearing trees. Neglect and improper management practices have contributed greatly to declining production in this State. The study reported in this circular was made in the summer of 1955 (1) to determine factors associated with and affecting apple yields, (2) to stimulate the interest of fruit growers in managing their orchards to better advantage, and (3) to provide information for increasing production.,of marketable fruit.

COMMERCIAL

'Taken from U.S. Census of Agriculture, 1954.

METHOD of STUDY Thirty-four orchards in 15 counties were selected from a list of apple growers. " Orchards with fewer than 100 trees were not included. Factors studied were: Yield, size, age, tree spacing, and varieties; soils, fertilizer, and cultural practices; location of orchard site with respect to direction of rows and slope; and prevalence of disease and insect damage, and methods of control. Data were obtained from personal interviews and records of
growers.

Soil and leaf samples were taken from each orchard for chemical analyses. Soil samples consisted of a composite of borShaded counties were included in the ings (0 to 6 inches) taken at ran- survey. Area north of black line is dom throughout each orchard. apple growing region of the State. Leaf samples included 100 most recently matured leaves of each major variety from current twig growth. FINDINGS Yield Classes Data from the 34 orchards studied are arranged into five different yield classes on the basis of production per tree, Table 1.
TABLE 1. NUMBER AND PER CENT OF ORCHARDS IN EACH YIELD CLASS

Yield class A B C D E

Orchards Number Per cent Yr. Bu. No. Pct. 11 4 12 5+ 16 4+ 2 6 11 3+ 12 4 71 2+ 9 26 17 0-1+ 15 44 TOTAL 34 100 1 One orchard was 35 years old and was not included in average. Average age
of trees

Average yield
per tree

2The

list was furnished by the API Agricultural Extension Service.

[4]

Classes are separated by a yield difference of 1 bushel per tree. Thirty per cent of the orchards studied were in the top 3 yield classes, while 70 per cent were in the 2 lowest. Of the 34 orchards studied, 10 were producing more than 3 bushels of apples per tree, which is low for commercial production. Forty-four per cent of orchards yielded less than 2 bushels per tree and 12 per cent had a yield of more than 5 bushels.
Cultural Practices

Soil Management. Many soil management practices were used in the orchards studied, Table 2. Sixty-eight per cent had a summer cover crop of either sericea lespedeza or native vegetation, mainly annual weeds and grasses. Twelve orchards were planted to a winter cover crop of legumes or a legume-nonlegume mixture. Intercropping was practiced in nine orchards with corn, cotton, soybeans, watermelons, and home or market gardens being the principal crops grown. One orchard was intercropped in the 3 highest yield classes, while in the 2 lowest 8 were intercropped. Grazing was more prevalent in the higher yield classes than was intercropping. Native vegetation was the main summer crop found in the orchards studied, Table 3. Eight orchards had sericea lespedeza as a cover crop, whereas two were clean cultivated. Apparently sericea lespedeza had little effect on yield, because there was little difference in the per cent sericea in each yield class. Since native vegetation was used as a summer cover crop, shallow or "trashy" cultivation was used on level or gently sloping land to reduce competition for moisture and nutrients. Winter legumes and legume-nonlegume mixtures were grown in 12 orchards, Table 4. Crimson clover and vetch were the two
TABLE 2. SOIL MANAGEMENT PRACTICES IN ALL ORCHARDS

Treatment

Total orchards studied Permanent sod (sericea lespedeza) Summer cover crop (native vegetation) Winter cover crop (winter legume or winter legume-nonlegume mixture) Intereropped Clean culture Grazed by: hogs cows chickens

Orchards receiving different treatments Per cent Number 34 100 8 24 44 28 12 9 2 5 5 1 35 26 6 15 15 3

[51

TABLE 3.

RELATIONSHIP OF YIELD CLASS TO SUMMER SOIL MANAGEMENT

Yield class A B C D E

Orchards Sericea lespedeza

Management practice Clean culture Native vegetation Pct. 0 0 25 0 7 No. 3 1 2 8 6 Pct. 75 50 50 83 40

No. No. Pct. No. 4 1 25 0 21 0 0 0 4 1 25 1 9' 2 22 0 15' 4 23 1 1 One orchard had soybeans as a summer cover crop. 2 Four orchards were intercropped.
TABLE 4. RELATIONSHIP OF YIELD CLASS

TO WINTER

SOIL MANAGEMENT

Yield

Orchards

with winter

legume or

class A B C D E

rcarlegume-nonlegumemixture No. 4 2 4 9 15 No. 3 0 1 2 6 Pct. 75 0 25 22 40

leading legumes being planted, while rye and ryegrass were the leading nonlegumes. Others included manganese bur clover, white Dutch clover, fescue, and orchardgrass. A higher percentage of orchards in yield class A had a winter legume than any other yield class. Fertilization. Fertilizer applications ranged from 103 pounds per acre in the lowest yield class to 1,095 pounds per acre in the highest class. In the four highest yield classes, all growers applied fertilizer either to the trees or to the cover crop, but only 20 per cent of the growers in yield class E applied fertilizer, Table 5. There was a direct relationship between yields and the amount of N, P2 05, and K20 applied, Table 6. Nitrogen ranged from 4 pounds per acre in the lowest yield class to 53 pounds in the highTABLE 5. RELATIONSHIP OF YIELD TO AMOUNT OF FERTILIZER APPLIED PER ACRE Average amount of fertilizer

YieldOrchards 1a class No. 4 2 4 9 15

To trees Lb. 583 570 495 302 13

A B C D E

applied per acre Ocreceiving To cover crops Lb. 512 325 300 54 90 [6]

Orchards Total Lb. 1,095 895 795 356 103 No. 4 2 4 9 3 fertilizer Pct. 100 100 100 100 20

TABLE 6.

RELATIONSHIP OF YIELD TO THE KIND OF FERTILIZER APPLIED

Yield

a class

Orchards No.

Kind and amount of fertilizer applied per acre

Total amount Lb. 1,095 895 795 356 103

N Lb. 53 34 33 28 4

P20 5 Lb. 113 86 75 15 11

K20 Lb. 86 50 93 10 11

A B C D E

4 2 4 9 15

est; P2 05 ranged from 11 to 113 pounds; and K20 ranged from 11 pounds in the lowest yield class to 93 pounds in class C, with an average of 86 pounds applied in class A.
Nutritional Status

Chemical analyses were made on leaf samples from each orchard to establish relationship between fertilizer rates and nutrient-element content of orchard trees. There was a direct relationship between leaf content and the amount of fertilizer applied per acre. On a dry weight basis, nitrogen ranged from 2.02 per cent in the leaves of the highest yielding orchards to 1.75 for the lowest; phosphorus, 0.15 to 0.11 per cent; potassium, 1.59 to 1.42 per cent; calcium, 1.12 to 0.92 per cent; and magnesium, 0.43 to 0.82 per cent. Boron was deficient in several orchards, while iron appeared to be adequate. As the rates of nitrogen fertilizer were increased, leaf nitrogen also increased. Average leaf nitrogen was low in all yield classes except A. There were individual orchards in every yield class that had a nitrogen content of 2.0 per cent or more, which is considered optimum.3
TABLE

7.

NUTRITIONAL STATUS OF THE 34 ORCHARDS STUDIED IN RELATION NATIONAL AVERAGES FOR HEALTHY, VIGOROUS APPLE TREES

TO

Element

Nitrogen Phosphorus Potassium Calcium Magnesium Boron Iron Sodium

Dry weight content National Alabama average average Pct. Pct. 2.36 1.85 0.23 0.13 1.64 1.50 1.61 0.99 0.43 0.36 p.p.m. 37 134 p.p.m. 63 245 345

Samples below National Alabama average average Pct. Pct. 100.0 48.5 100.0 53.0 65.0 51.5 98.5 50.0 80.0 53.0 44.0 1.5 60.0 58.0 35.0

Magness, J. R. Fertilization: Both Ground and Foliage Methods Discussed. Eastern Fruit Grower. 13:8-10, 18, 20-22, 24, 26. 1950.

[7]

When compared with the national average nutritional status4 for healthy, vigorous apple trees, the 34 orchards studied were below national averages for the major elements analyzed, Table 7. Boron and iron levels were higher than those for national averages.
Soils

Orchards in this study were located on four general soil textures, Table 8. A higher per cent of the orchards were located on sandy loam soil. Clay loam was the next largest soil type. Five orchards were located on gravelly sandy loam or clay. There was no evidence that soils influenced yields.
TABLE 8. RELATIONSHIP OF YIELD CLASS TO SOIL TEXTURE

Orchards in each soil texture
Yield

class

Orchards No. 4 2 4 9 15 34

A B C D E TOTAL

Sandy loam No. 3 1 4 3 10 21

Clay loam No. 0 1 0 3 4 8

Gravelly sandy loam No. 1 0 0 1 0 2

Clay No. 0 0 0 2 1 3

Tree Spacings

In a majority of the 34 orchards, trees were spaced 30 to 40 feet, Table 9. Spacings were usually 35 by 35 or 40 by 40 feet. Trees were spaced 30 to 40 feet in approximately 68 per cent of the orchards. Thirty-two per cent had 20 to 30 feet between trees. In some of these closely spaced orchards, crowding was beginning
TABLE 9. RELATIONSHIP OF YIELD CLASS TO TREE SPACING

Yield class A B C D E
TOTAL

Orchards No. 4 2 4 9 15
34

Orchards with different tree spacings 20 to 30 feet No. 2 0 2 3 4
11

30 to 40 feet No. 2 2 2 6 11
23

Kenworthy, A. L. Composition of Delicious Apple Leaves from Several States. Paper No. 25. Presented to 51st Ann. Meeting Amer. Soc. Hort. Sci., Gainesville, Fla. 1954. [81

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Diseases and Insects

Farmers growing early maturing varieties and following a good spray program were keeping losses to a minimum. Growers in the four highest yield classes sprayed more often than those in the lowest yield class, which is reflected in the per cent damage caused by major diseases and insects, Table 11. Bitter rot, Glomorella cingulata, and fire blight, Erwinia Amylovora, are the most serious diseases of apples in Alabama. Fire blight damage was
TABLE 11. RELATIONSHIP OF YIELD TO PREVALENCE OF DISEASES AND INSECTS

Yield class

Orchards Orcards No.

Disease and insect damage Fire blight Pct. 12 15 16 17 23 Apple scab Pct. 25 25 30 10 45 Bitter rot Pet. 15 25 32 20 59 Codling moth Pct. 18 20 24 20 51 San Jose scale Pct. 20 20 32 20 53

A B C D E

4 2 4 9 15

lowest in yield class A. Several of these growers were using antibiotics for control of the blight organism. Damage due to San Jose scale and codling moth were approximately the same. Other diseases and insects causing damage to apples in Alabama included a root rot organism, round- and flat-headed apple tree borers, and leaf hoppers. All growers in the top three yield classes owned spray machines, Table 12, and followed a regular spray schedule. Some growers in yield class E owned spray machines but had not used them in the past few years. Two of the growers with young orchards did not own spray machines but were using hand sprayers.
TABLE 12. RELATIONSHIP OF YIELD TO SPRAY MACHINES OWNED

YieldGrwrusn Orchards class No. A B C D E
TOTAL
1

Growers owning spray machines No. Pct. 4 2 4 7 11
28

Growers using No. 4 2 4 71 4
22

4 2 4 9 15
34

100 100 100 77 73
83

Two sprayers were hand-type. [10]

RECOMMENDATIONS

for INCREASING PRODUCTION

Fertilization One and one-half pounds of 8-8-8 fertilizer per tree per year of age, not exceeding 30 pounds per mature tree, gives good results. When orchards are in sod or non-legume winter cover crop, 30 additional pounds of nitrogen per acre is needed. A total of 500 to 600 pounds of 0-14-14 or 0-16-8 fertilizer should result in good growth of legume cover crops in the fall. Soil tests made every 2 or 3 years will determine lime needs. Disease and Insect Control A good spray schedule begins in the dormant season and continues until harvest. Spray applications every 7 to 10 days during the fruiting season ensure good pest control. It is important that sprays be applied on time and of the correct mixture for the material being used. Good control of insects and diseases were obtained at the North Alabama Horticulture Substation by using regular applications of 2 pounds of 50 per cent Captan and 2 pounds of 15 per cent wettable parathion per 100 gallons water. A sod of sericea lespedeza, winter legume, or legume-nonlegume mixture is recommended for mature orchards. Tree and cover crop competition can be reduced by mowing regularly during summer. Cover crops are left on the ground to serve as a mulch. Additional mulch of oat or wheat straw placed around the trees prevents excessive growth of cover crop under trees and conserves soil moisture, especially when trees are young. Annual pruning will remove diseased wood, train the tree, and increase the amount of marketable fruit. Fruit thinning when a heavy crop is set increases fruit size, reduces limb breakage, and reduces biennial bearing. New Plantings Sandy loam soil with a topsoil of 12 to 18 inches and a welldrained clay subsoil is preferred for new apple plantings. It is best to locate the orchard on a northern slope with good air drainage. It is desirable that the slope not be too steep for movement of machinery through the orchard. Trees can be spaced 28 by 28 feet if thinned. Where land will permit, a 35- by 35- or 40- by 40-foot spacing is more desirable. Trees may be planted on the contour or square depending on the topography of site. Based on variety tests and surveys, varieties recommended for new plantings are red strains of Delicious (Richard and Starking), Golden
[11 ]

Delicious, Winesap, Saint Clair, Atha, and Summer Champion. No variety should be more than two rows from a pollinating variety. Young orchards may be intercropped for the first few years provided crops are not planted closer than 6 feet to the tree row. It is a good practice to cultivate and mulch young trees.