While it is exciting and gratifying to see all the new fruit appearing on your trees in the spring, it is necessary to remove some immature fruit in order to get the large, strong, healthy fruit you desire at harvest. Many fruit trees set more fruit than a branch can support. Leaving too much fruit on a branch weakens it, can lead to disease from poor air circulation, and results in a leaf-to-fruit ratio that is not optimum. A single piece of fruit needs enough leaves to ensure photosynthesis brings it the proper nutrients to thrive. For example, a good leaf-to-fruit ratio for most apples and peaches is 40 to 75 leaves per single fruit. If you have not already, it is time to get out there and reduce the amount of fruit in your trees! You won’t have as much fruit, but the size and quality will be much better and your tree and its fruit will be healthier.
Hopefully you have pruned your fruit trees for size and ease of harvest in the fall and you can easily reach the fruit you need to remove. It is always something of a judgement call, but it is best to remove fruit when it is about ¾ inch in diameter, leaving the largest behind. Fruit can be removed by twisting the stem between thumb and forefinger, but clippers are easier, especially for apples and pears, which have stronger stems. Don’t pull or yank on the fruit!
Peaches and nectarines should be thinned to about 5 to 7 inches apart. Apricots and plums, being smaller, can be spaced a bit closer together along the branch. Unlike stone fruits, which produce one fruit per bud, apples and pears produce a cluster of flowers and fruit from each bud. Thin to one fruit per cluster. If the overall crop is light, two fruits may be left in an individual cluster, separated from each other if possible. Retain the largest fruit whenever possible, and remove any damaged fruit. If the crop is heavy, fruit should be spaced no less than 6 to 8 inches apart.
Fruit thinning is not necessary for nut trees and is usually not required for citrus. After petal fall (a naturally occurring event for citrus, usually in April and May), the young citrus fruit undergo rapid cell division. It is not uncommon for many small pea-sized fruit to drop about 1 month after bloom. Later in spring and early summer, larger golf ball-size fruit may drop if conditions that limit growth such as excess heat, lack of soil moisture, or adverse weather exist.
Fruit can be controlled by blossom thinning as well, but this can be tricky and hard to control, since early bad weather can cause the loss of blossoms, getting you off to a bad start.
As mentioned briefly above, pruning and trimming your fruit trees in the dormant season helps to make for a better harvest. Pruning correctly helps to control the size of your trees, making it easier to thin and pick fruit and avoid the use of a pruning pole, which can be clumsy at best. Pruning increases the strength of the limb which is going to support the fruit. Removing excess wood helps regulate fruit bearing and allows maximum exposure to sunlight. And, of course, it renews the fruitwood so it can continue to bear strong flowers and buds.