Fruit Tree Care: Fruit Trees Experience June Drop

As we look at a fruit tree, such as an apple, in full bloom we realize that if every flower were to produce a fruit the tree would collapse under the weight. Actually, only about one bloom in 20 is needed to develop a good crop on a full-blossoming apple tree. Many blossoms drop off soon after bloom, but natural fruit drops occur even as the young fruits begin to increase in size. In many fruits there may be two general drop periods. The first of these begins soon after flowering, and primarily consists of small fruits that have not pollinated or been poorly pollinated. After this initial drop, there may be a slowdown in fruit dropping until the well known "June drop" begins.

In mild climates, June drop actually may occur in May and continue for two or three weeks. June drop is most often a result of competition for nutrients and water. June drop is more obvious than the earlier drop because the fruit are larger and more noticeable. Apples may be as much as an inch in diameter when this occurs. Fruits which contain weak or few seeds resulting from poor pollination are the first to drop. Even though natural fruit drop occurs, fruit trees may still maintain a load of fruit that is too heavy. Such fruits as apples will not bear well the year after a very heavy load of fruit has been allowed to develop.

For good fruit size as well as avoiding biennial bearing, apples and pears should be thinned so that there is six to eight inches between fruits, with four to six inches between peaches, and two to three inches between plums. Apricots should be far enough apart so fruits are not touching. Other factors can lead to poor pollination with resulting fruit drop that may greatly reduce a crop. Temperatures below 40 degrees during the flowering period can reduce bee activity and also reduce pollen germination. While some pollen germination occurs between 40 and 50 degrees, optimum temperatures for pollen development and pollination of flowers occurs close to 70 degrees.

Even rain and wind during pollination time can inhibit fruit set. Bee activity can be inhibited by cool temperatures. High winds can dry the stigmas of the flowers or simply whip off flowers. Cold temperatures and frost normally ruin flowers and small fruits resulting in a more prompt drop. Even though weather conditions may be ideal for pollination, other problems can lead to fruit drop or lack of fruit set. Some fruits, such as many apples and pears, require more than one variety for cross pollination.

Peaches are self fruited, while apricots are somewhat self fruitful, but generally produce better crops when cross pollination can occur. Infection by insects and disease also leads to premature fruit drop. Many of these problems attack fruits in very early stages, so pest control methods must begun early and maintained throughout the fruiting season.

Tree nutrition is also an important factor in fruit set. If trees were weakened during the previous season by either diseases, insects, low levels of soil nutrients, or excessively large crops June drop will be high and fruit set reduced.

Fruit Tree Care And Production Primer, by S. Mills.