University of Vermont Extension
Department of Plant and Soil Science
Summer News
Article
WHY
FRUIT
TREES FAIL TO BEAR
Dr.
Leonard Perry, Extension Professor
University of Vermont
Got fruit trees but no fruit? There are six main reasons fruit
trees may
fail to bear fruit.
Fruit
trees may not bear when too young. The
time between planting and bearing will vary with the tree type,
variety, and
rootstock. Trees grafted onto dwarfing
rootstocks generally will begin bearing one or two years earlier than
those on
standard rootstocks. Apples may take 2
to 5 years to bear fruit from planting, sour cherries 3 to 5 years,
sweet
cherries 5 to 7 years, and 4 to 6 years for pears and plums.
Unhealthy trees may bear poorly if
at all. Keys to good health include
proper placement when planting with well-drained soil and full sun.
Shade can
reduce and delay flowering, reducing the size and number of
fruit. Allow plenty of space between trees so they
wont be crowded as they grow, competing for light and nutrients.
Cultural practices for good tree
health include cultivating or mulching to reduce weed and grass
competition for
nutrients and water. Fertilize each
spring with compost, a commercial fertilizer, or both. Prune
young trees early each spring to
develop a strong framework to support the fruit. This includes a
good tree form with space
between branches to allow sunlight in, and to renew fruiting wood.
The climate and weather can kill
flower buds. Although most hardy fruits
need a certain amount of cold, termed "chill requirement", too much
cold can be damaging. Extreme cold is
particularly damaging to peach and sweet cherry fruit buds. As
buds grow on any tree, the more they
open the more susceptible they are to frost.
Buds often withstand down to 24 degrees (F), yet open flowers may be
damaged below 27 degrees (F). Even if
the flowers look fine, if the center pistils are damaged the flowers
wont bear
fruit. Planting on a gentle slope with
good air drainage, not on a windy hilltop or low frost pocket, helps
prevent
spring frost damage.
Without good pollination, fruit
trees may have many flowers but fail to produce fruit. To have
good pollination trees need
pollinators (generally bees), and some need two or more
varieties. These "self-unfruitful" varieties
cannot produce fruit from their own pollen, but need pollen from
another variety
planted nearby. Included in this group
are most apples, pears, sweet cherries, and both Japanese and American
plums.
Some trees, often apples, are
"biennial bearing"-- they bear heavily one year and little the
next. This tendency varies with
variety. Since flower buds for one year
actually are formed during the previous summer, an especially heavy
crop one
year can lessen the flowers (and so fruit) the following year. If
a fruit tree seems to be bearing
biennially, try early and heavy thinning of fruit during the summer
they are
producing the most. During early summer
remove all but one fruit per cluster, with 3 to 7 fruit for every 3
feet along
branches.
There may be no fruit thanks to
diseases and insects. Those that
attack leaves may just make them unsightly, but may weaken the tree
over
time. Those that attack the fruit may
make them inedible. Those that attack
the blossoms prevent fruit from even forming.
There are many resources online to identify and control tree fruit
pests
and diseases, including one from Cornell University that covers proper
culture
as well (www.gardening.cornell.edu/fruit/homefruit.html).
Return to
Perry's Perennial
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