Failure to control peach leaf curl disease for 3-4 may kill a tree, he said. The first application is recommended around leaf fall in the autumn. Then, around December 15 the second spray is recommended. Symptoms of peach leaf curl appear in the spring, and include curled, distorted and reddened leaves. As the disease proliferates, thickened areas on the leaves turn yellowish-gray and velvety.
Spores are then ready to spread to healthy leaves.
During wet, rainy seasons, the infection is spread over the tree to leaf buds and can become so heavy that the tree is defoliated and will drop fruit that may have been starting to form. If in the spring, when leaves come out, a few infected leaves appear, it is too late - your peach or nectarine tree is infected, Penhallegon warned. Once the trees are infected, nothing can be done to stop the infection because it has already happened. If the infection is small, carefully pick each distorted leaf from the tree and put it in a paper bag immediately, this will help minimize spores flying to healthy leaves. Destroy the bag and infected leaves you have picked from the tree by burning in an approved manner or throwing the bag into the garbage can.