Answer: Based on your description, it sounds like your tree is suffering from peach leaf curl, a fungal disease. It causes young leaves to develop yellow to red discolorations, then the leaves can thicken and look crisp or crackled. The leaves and shoots end up curled and deformed. During the next stage, a white powdering covering develops and finally the leaves either yellow and drop, or they stay on the tree and turn dark brown.
Unfortunately, it is too late to control the fungus on your tree this season, although you may wish to remove and destroy any infected leaves. Peach leaf curl must be prevented during the winter. This is because the fungus overwinters on twigs and buds, and infection occurs as the buds swell in the early spring.
Next year, you can prevent the infection by using Soap Sheild, an extremely effective new fungicidal spray that is easy on the environment (available from Gardens Alive, 5100 Scheneley Pl., Lawrenceburg, IN 47025; ph# 812/537-8650). Your county extension office (ph# 217/877-4564) should be able to provide you with the spray schedule and timing best suited to your local area.
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