Avocado trees originated in the south of Mexico, but the trees have been in cultivation for so long it is impossible to pinpoint their origins. Avocado trees prefer warm weather, but hardy trees may grown in regions with winter temperatures as cool as 19 degrees F. Weather and pest problems may be why avocados start falling off the tree too soon.
The first flowers appear on the avocado tree in January, often before the leaves. Flowers continue appearing through March. When pollination occurs, these flowers develop intro fruits. Not all flowers will become pollinated even under ideal growing conditions. Avocados naturally drop some fruits and flowers early. The first fruits drop in spring, and more may start falling from the tree in May and June. The healthiest fruits are left to mature, while others fall. In the normal fruiting process, some fruit drop too soon, but other factors may be at work when avocado fruits are falling.
Anthracnose, a fungal disease, strikes nearly mature avocado fruits. The disease initially appears as tiny brown-and-black spots on fruits. The spots eventually grow larger, causing cracking in the fruits. Anthracnose usually does not cause significant fruit loss on tress, but as cracks open up on fruits and damage results a few may begin falling from the tree too soon.
Wild opossums eat avocado fruits and will return to known food sources. Sometimes, opossums climb trees searching for fruits if they are not available on the ground. As opossums climb around the limbs, they shake unripe fruits from the tree.
Avocado trees grow best in well-drained soil. Excessively moist, waterlogged soil causes root rot disease. Foliage turns yellow, and avocado fruits fall too soon when root rot is present. Avocado trees not receiving enough moisture may drop their fruits too soon as well. Know what the trees need. Test the soil frequently to ensure ongoing healthy cultivation. If soil is dry and hard to the touch, water it. If soil is so wet that you are able to squeeze moisture from it with your hand, cut back watering or amend the soil to improve drainage.