FRUIT TREES: CARE
Ch. 11, pp. 21 - 23
fertilization | thinning |
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.
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
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
||Self-fruitful with the exception
of J.H. Hale variety which has to be pollenized by another
||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.
||Self-unfruitful. Always need two
varieties to ensure good fruit set. Variety Seckel is not a good
||Sweet cherry is self-unfruitful
and needs two varieties to ensure good crop set. Sour cherry
varieties are self-fruitful.
||Self-unfruitful as a rule with
exception of Santa Rosa which will set fruit fairly well without
cross-pollination. Better to have a pollenizer.
||Self-fruitful but cross
pollination will ensure good fruit set. Western Schley is a good
pollenizer for Cheyenne, Mohawk, Choctaw.