Well before it is time for harvest, the size of the New England apple crop is impacted by “June drop.” Occurring now, it is a time when the apple tree divests itself of surplus fruit competing for food, water and nutrients. June drop enables the remaining apples to mature to a good size, without overwhelming the tree.
The fallen apples typically are about one-half inch to one inch in diameter. Even with this naturally occurring governor, farmers follow June drop with additional thinning, often by hand, to ensure a good crop. Only the best-looking, healthiest apples are left to ripen.
If allowed to, almost all the blossoms on an apple tree will bear fruit. But as little as 5 percent to 10 percent are needed for a full crop. By removing excess fruit, the tree is spared from the threat of breaking under its own weight, and does not have to expend energy producing lots of smaller apples.
Another reason for thinning is to allow development of flower buds for next year's crop. This is especially important for varieties that bear fruit in alternate years.