Why Your Fruit and Nut Trees Don’t Produce

Fruits and nuts (which are also a fruit) are the reproductive structures of a tree.  Trees produce fruits and nuts to propagate their species.  Successful fruit and nut production requires flowering, pollination, and fertilization.  These are processes that trees must go through every year to reproduce.  If any of these processes are disrupted, fruit and nut production will not happen.  Sometimes these processes are disrupted by factors we cannot control.  Most disruptions, however, can be avoided with careful planning and some minor manipulations.  Here are the most common reasons why trees won’t produce and what you can do about it:

  1. Immaturity – Trees spend the first few years of their lives trying to establish a strong root system and aren’t too worried about fruit production during that time.  Fruit trees typically won’t produce for the first 2 to 7 years, depending on species.  Grafted pecan trees don’t produce during the first 5-10 years and many native pecan trees don’t produce until they are 15 years of age.
  2. Pollination – This is the big one.  Flowers must be pollinated to produce fruit.  Pollination is usually accomplished by birds, bees, and wind and these elements must be present at the right time for trees to pollinate.  Some trees are self-pollinating meaning that they have both male and female flowers or flowers with both male and female reproductive structures on the same tree that are capable of pollination.  Some of these self-pollinating trees, such as many pecan varieties, have both male and female flowers but they bloom at different times, making self-pollination difficult.  Some trees are gender-specific, meaning that an individual tree may have only male or female flowers and multiple trees are necessary to ensure that pollination takes place.  Many trees, such as most apples, plums, and pears are not self-fruitful meaning they need pollen from a different variety (cross-pollination) to produce fruit.  There are charts available showing the different pollination needs of various fruit and nut trees.
  3. Weather – Trees need a certain amount of chill hours (consecutive hours where the temperature is below 45 degrees Fahrenheit) to produce fruit.  However, too much cold can damage or kill buds that would have turned into flowers.  Fruit production is also hurt when a late spring frost kills blooms or fruit that have already developed.  Another issue is the weather conditions during bloom.  If it’s cold and rainy, the activity of pollinators will be limited.
  4. Pruning – Regular pruned trees are more apt to produce quality fruit.  See MU Extension guides on fruit and nut tree pruning.
  5. Spacing – Trees must be placed close enough that they can cross-pollinate (50-100 feet) but not so close that they compete with each other for light, water, and nutrients.
  6. Soil Conditions – In general, a well-draining soil with adequate levels of fertility is desired for maximum fruit production.  Some fruit and nut trees are able to handle soils that stay a little wetter or a little drier but fertilization is an absolute necessity.
  7. Alternate Bearing – Many fruit and nut trees have developed a cycle of alternate bearing, meaning that fruit or nut production is heavy in “on” years and nearly absent in “off” years.  During the “on” years the numbers of fruit can be so high that fruit size will remain small.  Trees do this as sort of an internal conservation practice so they don’t use up all of their resources.  The best way to end this cycle is to utilize practices that promote plant health and moderate vigor such as pruning, spraying, irrigation, and adequate (but not too much) fertilization.
  8. Insects and Diseases – Fruit and nut trees are susceptible to a great number of insects and diseases.  Spraying is a requirement for producing quality fruit.  Selection of varieties that are resistant to certain insects and diseases can reduce, but not eliminate, the need for spraying.  MU Extension has a very handy guide called “Fruit Tree Spray Schedule for Homeowners”.  Ask for it in your county extension office.

Source: Travis Harper, Agronomy Specialist