Your peach tree appears to have a disease called peach leaf curl. Taphrina deformas, a fungus, infects leaves, fruit and young twigs. The infected leaves become distorted, puckered and thickened. As the infection progresses, affected leaves turn gray and powdery as a result of the production of fungal spores on the leaf surface. Shortly thereafter, these leaves turn yellow or brown and drop. Fruit which becomes infected tends to drop shortly after infection occurs. Infected twigs are swollen and stunted, usually with deformed leaves at their tips.

Spores produced by the fungus on leaf surfaces are washed or blown onto peach twigs and buds. During summer and the following winter, these spores remain lodged in bud scales or crevices in the bark. As the buds open in spring, the spores germinate during periods of frequent rains. Only juvenile plant tissues are susceptible to infection, so if no spore germination occurs at bud break, there will be little damage that year.

Spores are capable of producing secondary spores known as bud conidia during periods of wet cool weather. Both spore types can remain inactive for several years on the peach tree until conditions are right for infection to occur. This explains why peach leaf curl can periodically cause severe defoliation even though it was not noticed the previous year.

Peach leaf curl can affect peach, nectarine, almond, and related species. It is common in unsprayed orchards. The disease is not serious except in rainy years when it can cause defoliation of unsprayed trees early in the growing season. This weakens the trees, making them more susceptible to winter injury.

For updated information on the preventive care of stone fruit trees, contact the cooperative extension agent in your state. Also check out the Missouri Botanical Garden's information page.

For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service