What Causes Lychee Fruit Drop?
If your fruit is dropping early, there could be several reasons. Lychee trees generally set more fruits than it is possible to hold, so some dropping can be the result of natural attrition. Stress can increase natural fruit drop in lychee, and stress may be increased by drought, temperatures that are colder than normal, or nutrient deficiencies. Lychee is notoriously ready to drop fruit early, so being careful to minimize stress is important. Other reasons for lychee tree dropping fruit at a high rate include infections and pests. There are several pests that may attack your tree and contribute to more fruit drop: lychee stink bug, fruitspotting bugs, erinose mites, and several types of moths and fruit flies. Downy blight disease causes brown lesions on fruit and early dropping. Birds can also cause fruit to drop early.
How to Minimize Early Fruits Falling from Lychee Trees
First, be sure that your tree is getting everything it needs to reduce stress. These trees require a lot of water, plenty of sun, a slightly acidic soil, and an occasional general fertilizer to be their healthiest. The right conditions will both discourage early fruit drop and help trees better resist infections and diseases. You can also look out for signs of disease or pests on your trees and take steps to manage them early to minimize the damage and fruit drop. Check with your local nursery to find out what sprays are best for your fruit tree. Another strategy for preserving more of the fruit on your lychee is to bag the fruits. Netting keeps birds off trees but not insects. Bagging the fruit protects it from both. To bag a lychee tree, use any kind of paper bag. Place the bags around individual panicles about six weeks after the tree has fully bloomed (the fruits will be about ¾ of an inch (2 cm.) long). You can secure the bag any way that is easiest, but simply stapling or tying it around the stem is adequate. Research has found that bagging a lychee tree is well worth the effort and the cost of bags, as it does increase fruit yield significantly. As a bonus, you won’t need to net the whole tree or use pesticides to deter insects and birds.
