Apricot trees are a "feast or famine" kind of tree, says Jerry Goodspeed, a Utah State University Extension horticulturalist. When things are good for apricots, they are very, very good and there is plenty of fruit, a beautiful and graceful tree and easy plant maintenance. However, diseases of apricot trees can seriously dent fruit crops and leave you with no fruit and stunted or distorted trees. The best way to stay on the "feast" side of things is to spot problem signs and symptoms early so that you can take every step possible to keep your apricot trees happy and healthy.
Shot Hole Disease
Also called Coryneum blight, shot hole disease starts out with small, black spots forming on the leaves of the tree. Left unchecked, the centers of these spots will rot out, making the leaves look as if they were sprayed with buckshot. In apricots, small, brown spots will also appear on the fruits around harvest time. These spots do not impact the taste of the fruit, but they do make it far less attractive. Over time, shot hole disease can also lead to cankers and distorted branches. You can control shot hole during the growing season by sterile pruning of affected areas and disposing of tree debris completely rather than allowing it to fall on the ground. You may also wish to treat the infection with a fungicide immediately after the flowers lose their petals and again when the leaves fall off the tree for winter.
Apricot trees may develop cankers as a result of bacterial infections that enter small, surface wounds on the tree. These knobby, orange, corky growths are spread by splashing rain that splashes the bacteria and fungi onto the surface of the tree. When spring temperatures are low while moisture is high, you are more likely to see these cankers. The best way to prevent cankers is to keep soil well-drained and to avoid pruning during dormancy. If your tree has cankers, then treating the surrounding soil for nematodes, which stress trees and leave them vulnerable to cankers, will likely help the tree resolve the problem on its own.
Peach Tree Borer
Because of its name, you might think that the peach tree borer would not bother apricot trees. However, this infestation is as common on apricots as it is on peaches. When the eggs, previously laid at the base of the tree, hatch, the larvae bore into the apricot tree. They eat the insides of the tree, causing defoliation, stunting and smaller fruit yields. There is little to be done for peach tree borers outside of preventative fumigation of the soil by the beginning of July and for the next two months to prevent the eggs from hatching.