By Steve Roark
Volunteer Interpreter, Cumberland Gap National Historical Park

This fall looks to be a good year for nut producing trees like hickory and beech, and oak acorns aren’t looking bad either. Fruit and nut production varies from year to year, and the reasons are many.

Sometimes when a tree is in declining health or enduring some form of stress, it produces a lot of fruit in hopes of reproducing and carrying on its DNA in case it dies, referred to as a stress crop. Back in the day farmers would beat the trunks of apple trees with a heavy stick to stress the tree and make it produce. Another cause of heavy fruiting is favorable weather that provides an excellent growing year, enhancing photosynthesis and food production that will provide energy for a great reproductive year the next growing season. Good fruit seasons are helped by the absences of damaging frosts in the spring. Poor fruiting years can be due to poor growing conditions for flower bud development, such as drought the previous summer. Sometimes a great reproductive year depletes reserves for producing flower buds and fruit the next season.

Sometimes the reason for feast or famine years is hormonal. Some trees are alternate year bearers, having high yields one year and little the next. A heavy fruit load one year pushes the next year’s buds towards becoming leaves rather than flowers; whereas a year with a lot of leaves pushes the following year’s buds to favor becoming flowers. The reason is a necessary balancing act. The ultimate goal of living things is to pass on its genes to future generations. Fruit production is an energy drain but necessary to produce seeds. Leaves produce food energy but can’t pass on genes, so a compromise is needed. Orchard growers can manipulate trees with alternate production tendencies by thinning out fruit during heavy years to allow the tree to put more energy into the remaining fruit and allow the tree to shift some energy to flower buds for next year. Fruit thinning works well for apples, plums, pears, and peaches.

Hunters and other wildlife enthusiasts are always on the lookout for good “mast years” when acorns, hickory and other nut trees produce abundant food crops. Mast years occur every 4-7 years, but their timing is a mystery. Scientists are unsure if it’s caused by some biological clock or a response to environmental cues. They do know that massive seed formation seems to occur on a year prior to favorable growing conditions and when the tree has room for new growth.