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).
           

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