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FRUIT TREES: CARE [continued]

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  MG Manual Reference
Ch. 11, pp. 21 - 23

[Care: fertilization | thinning | pollination | irrigation | pruning ]


The primary reasons for thinning fruit is to improve fruit size and quality. In some instances fruit thinning aids in the prevention of irregular and alternate bearing. In addition, the removal of immature fruit allows for the elimination of damaged or malformed fruit. Removal of immature fruit will reduce overall yield; therefore there is a sacrifice for improving size and quality in terms of pounds of fruit produced.
The fruit crops that respond to fruit thinning are peaches, plums, apricots, nectarines, apples, pears and grapes.
Thinning Techniques Top

Stone Fruit -- The best time to thin and obtain maximum fruit size is during bloom or a rule of thumb would be the earlier the better. Since it is difficult to thin during bloom for many reasons, it is suggested that thinning be conducted right after petal fall. This allows the person doing the thinning to remove abnormal fruit in terms of shape and size. Fruit should be spaced 6-8 inches apart. For peaches and nectarines leave no more than two fruit on a shoot. A mature peach tree should not yield more than 500 fruit on average. In general thinning cannot be too early or overdone.
Apples & Pears -- Two important factors related to apples and pears include: 1) fruit are produced on spurs and; 2) flowers are in clusters of 5 with the bloom in the center known as the "king blossom" surrounded by lateral blossoms. Both apple and pears have a strong tendency to alternate bear, that is produce large crops one year and no crop the next. Another important fact is that a spur will not produce fruit in consecutive years. Therefore the object in thinning is to eliminate all flowers and small fruit on every other spur. This has to be done within 30 days after bloom or the thinning will not be effective in reducing alternate bearing. When thinning to increase fruit size leave only one fruit in a cluster. The largest fruit will come from the king blossom or fruit. Leave this one for maximum fruit size. Space fruit 6-8 inches apart regardless of spur placement on a limb.


Pollination is the transfer of pollen (male part of flower) to the stigma (female part of flower) of a flower for fruit to set and seeds to develop. Seeds cause the fruit to develop properly. If both the pollen and stigma are from the same flower or from another flower from the same variety, the process is called self-pollination. Fruit trees that set fruit as the result of self-pollination are called self-fruitful. If the pollen has to come from a different variety for pollination to occur the process is called self-unfruitful. Therefore two varieties have to be planted for fruit set to occur. This is called cross-pollination. The following is a pollination guide for various fruit trees grown in Arizona.
Fruit Tree Pollination Guide

Fruit Pollination Requirements
Peaches Self-fruitful with the exception of J.H. Hale variety which has to be pollenized by another variety
Apples As a rule self unfruitful and need two varieties to ensure good fruit set, Red Delicious and uts strains need a pollenizer. Golden delicious is a good pollenizer. Rome strains, Yellow Transparent, and Grimes Golden are usually self-fruitful. Winesap and Stayman winesap have sterile pollen. Crab apples that bloom at the same time as apple can be used as pollenizers.
Pears Self-unfruitful. Always need two varieties to ensure good fruit set. Variety Seckel is not a good pollenizer.
Apricots Self-fruitful
Cherries Sweet cherry is self-unfruitful and needs two varieties to ensure good crop set. Sour cherry varieties are self-fruitful.
Nectarines Self-fruitful
European Plums Self-fruitful
Japanese Plums Self-unfruitful as a rule with exception of Santa Rosa which will set fruit fairly well without cross-pollination. Better to have a pollenizer.
Pomegranate Self-fruitful
Figs Self-fruitful
Berries Self-fruitful
Almonds Self-unfruitful
Pecans Self-fruitful but cross pollination will ensure good fruit set. Western Schley is a good pollenizer for Cheyenne, Mohawk, Choctaw.
Walnuts Self-fruitful

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