When and How to Thin Fruit Trees

Thinning your fruit trees early can help stop them from going into alternate bearing. M. Schuppich/Shutterstock

Q: We moved into this house two years ago. We were told there was a 3-year-old apple tree in the backyard. Last year, there was no fruit, but this year, the tree has thousands of small apples. First, is this normal? One year of no fruit and the next with too much? Second, will the tree drop a lot of apples prematurely, or do we need to prune them out?

A: The tree may have been too young to have fruit last year, but it should have fruit from now on. Apples, pears, peaches, and other trees will sometimes develop what is called alternate bearing or biennial bearing. It is easy to understand but hard to fix.

During the summer when the tree is developing a lot of fruit, nuts, or seeds, a lot of the carbohydrates, nutrients, and other chemicals produced by the tree go into the fruit. There isn’t much left over for the tree to produce flower buds. Without many flowers blooming during the second year, there won’t be many fruits produced, so the tree uses its resources to produce lots of flower buds. Lots of flowers during the third year mean—you guessed it—lots of fruit, and we are back to where we started. We sometimes call the fruiting year the “on year” and the nonfruiting year the “off year.”

Of course, this is a problem for orchards. An off year means no sales, but too much fruit is also a problem, as many could rot in the orchard if not enough labor is available to harvest. Much of the fruit may be too small to sell, as the tree can’t grow all of the fruit to full size. Also, too much fruit can break branches, damaging the tree.

So, what do you do this year? A tree with that much fruit will probably go through what is called “June drop.” The tree can’t support so much fruit, and it will go through a natural thinning on its own.

On a young tree like yours, it is better to cut out a lot of fruit so the tree can continue to grow more branches and roots. Just keep a few fruits on a branch. It is better to have less fruit this year to grow a stronger tree for the future. Even on an older tree, it is a good idea to reduce the number of fruits as early in the summer as possible. The tree will develop more leaves and flower buds this year and not go into alternate bearing.

Apples often have clusters of five fruits: a central apple that is larger and four smaller ones around it. Keep the one large apple. Thin the single large apples to an average of 6 inches apart on a branch. Thin large fruit such as apples, peaches, and pears to an average of 6 to 8 inches apart; plums about 4 inches; and apricots between 2 and 4 inches. It is better to cut them off than pull them so you don’t yank the small branches off.

After you have thinned the fruit, you will want to keep the tree healthy and strong for a good crop of apples. Water can be a limiting factor in fruit size and quality. Keep the soil damp but not waterlogged this summer.

From the tree’s viewpoint, alternate bearing may be beneficial. During the on year, more pollinators may be available. During the on year, more of the fruit, nuts, or seeds will be missed by insects and other animals that want to eat them. Animals that eat some and store some will store more seeds, and that means more will sprout later.

Email questions to Jeff Rugg at [email protected]. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at Creators.com. Copyright 2021 Jeff Rugg. Distributed by Creators Syndicate.