Pollination of Fruit
A variety of plants in Texas experience fruit problems every
year, from bearing no fruit at all to instances where immature
fruit drop. However, fruit injury can also occur from frost
or subsequent cold temperatures.
However, the weather can't be blamed for all fruit problems.
All fruit plants require flower pollination in order to produce
fruit. Pollination is the transfer of pollen from the male part
of the flower (anther) to the female part (pistil) of the same
flower or another flower of the same type. Seeds needed for
propagation are derived from the fruit.
Gardeners, however, are more likely to be interested in the
particular fruit as a food item, rather than as part of Mother
Not all plants will set the maximum fruit crop when pollen
is available only from the same plant. Before the maximum amount
of fruit will form, pollen must come from different plants of
the same kind for cross-pollination. The absence of the second
pollinator is often why single trees in the garden flower heavily
but never set a single fruit.
Weather does have a bearing on flowering and fruit development,
even with several pollen sources available. Windy or rainy weather
during flowering often slows bee activity. High temperatures
may also dry the female reproductive parts, which prevents pollen
Flowers with higher nectar content will often lure bees away
from fruit plants that have lower nectar contents in their flowers.
Overuse of insecticides during the flowering period will reduce
the number of bees and the subsequent pollination of flowers.
In cross-pollination, the pollen of the selected varieties
must be compatible. The flowering date of the pollen source
must match the flowering date of the plant to be pollinated.
If both varieties aren't flowering at the same time, fewer fruit
will develop. Some varieties take longer to come to flowering
age, but this is only a short-term concern that will correct
itself in a few seasons.
Cross-pollination is essential for a maximum apple crop. Trees
should be less than 100 feet apart to assure optimum pollen
Pecans and black walnut trees are self-fertile, but their
pollen is often not shed when the stigma of the pistil is receptive,
so fruit may begin to form and then drop during the season.
Pecans are monoecious, meaning they produce separate male and
female flowers on the same tree. Some varieties develop the
male flowers—called catkins—first, and are termed
protandrous. Other varieties produce the female nutlets first
and are termed protogynous. Each type will cross-pollinate with
the other. If you are planting two pecan trees, plant one of
each pollination type. Varieties that are of the protandrous
type (shed pollen fruit) include Cheyenne and Desirable. Varieties
that are protogynous (forms bloom first) include Choctaw, Kiowa,
Mohawk and Shawnee.
Fruit drop can be a problem with Japanese persimmons due in
part to pollination considerations and environmental stress.
Separate male, female and/or perfect (both male and female)
flowers can be produced on the same tree on the current season's
growth. Tane-nashi, Hachiya and Tamopan produce flowers that
develop into excellent parthenocarpic (non-fertilized) fruit
without pollination and without seeds. These varieties can,
however, be pollinated by common persimmon or the Fuyu variety
to produce fruit with seeds.
Fruit drop is common on parthenocarpic fruit without true
seeds. (Seeds produce chemical hormones that improve fruit retention.)
Any environmental stress such as drought, waterlogged soils,
extreme-heat, etc. can worsen this fruit drop problem. Thus,
a thick layer of mulch over the root zone and regular, deep
watering is recommended.
Fruit trees such as nectarine, peach and quince should be
able to produce adequate fruit crops alone. Additional trees
will increase the harvest and add that extra assurance of enough
pollen for all of the flowers. Pear trees are self-fruitful,
but a second variety will also improve the crop.
Nearly all of the small fruits, berries and brambles are self?fruitful.
Remember, all plants flower and bear fruit as long as the laws
of nature are understood and met. When purchasing trees for
spring planting, keep these principles of fruit and nut pollination
in mind—it could avoid disappointment later.