PEACH LEAF CURL Taphrina deformans   F A C T S H E E T

Introduction

Peach leaf curl is a springtime disease of peach, nectarine, almond, and related ornamental species caused by the fungus Taphrina deformans. This disease is common in unsprayed orchards. Peach leaf curl 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.

Symptoms

Taphrina deformans can infect leaves, fruit, and young twigs. Infected leaves become distorted, puckered, and thickened (Fig. 1 & 2), initially with a distinct reddish or purple coloration. As infection progresses, affected leaves turn gray with a powdery appearance 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.

Figure 1: Deformed leaves of peach. Figure 2: Deformed leaves of peach.

Disease cycle

Spores produced on the leaf surface by the fungus are washed or wind blown onto peach twigs and buds. They remain lodged in bud scales or crevices in the bark throughout the summer and following winter. These spores germinate during periods of frequent rain as the buds open in the spring. If rains do not occur at this time, the spores remain inactive and little or no infection occurs. Only juvenile plant tissues are susceptible to infection, so if no spore germination occurs at bud break, then little damage results for 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 growing season.

Management Strategies

Peach leaf curl can be managed by a single, dormant application of a registered fungicide. Homeowners in New York State may use one of the following fungicides on trees in their home orchard: basic cupric sulfate, chlorothalonil, copper, myclobutanil, Hi-Yield Lime Sulfur, Kop-R-Spray, or a commercially prepared dormant spray mix containing copper. Be certain the product(s) purchased are registered for the intended use, and follow label directions. Do not use these sprays on apricots. These sprays may be applied in the fall after the leaves have fallen or in early spring 3 to 4 weeks before the buds begin to swell. They are not effective after bud break.

Copper may also be used to treat ornamental peach trees in the home landscape. Apply in the spring before buds open. Additional products may be available for use by commercial applicators for nursery, orchard or landscape applications. For commercial applications, please refer to the appropriate commercial pest management guidelines, or contact your local Cooperative Extension Office for more information on currently registered products. The varieties Clayton, Q1-8, Five Star Curlless, Indian Blood Free, and others are reported to be resistant.

Updated, SLJ, 2/05