Pests in Gardens and Landscapes: Quick Tips
Peach Leaf Curl
Foliage and shoots damaged by peach leaf curl.
Leaf puckering and reddening.
Peach leaf curl is a fungal disease that affects only peach and nectarine trees. Distorted, reddened foliage in the spring is a distinctive symptom. New leaves and shoots thicken and pucker and later may die and fall off. An infection that continues untreated for several years can lead to a tree’s decline. To prevent peach leaf curl, treat peach and nectarine trees with a fungicide every year after leaves fall. Treatment in spring, after symptoms appear, won’t be effective. When planting, consider peach varieties resistant to the disease.
Look for symptoms in spring.
- New leaves and shoots redden and pucker. Leaves may yellow or be covered with powdery gray spores; they also might drop.
- Cool, wet spring weather prolongs disease development.
- A second set of normal leaves will replace fallen leaves, and tree growth will appear normal after weather turns dry and warm (79º to 87ºF), although spores that can infect next year’s growth may remain.
- Symptoms won’t appear later in the season.
Treat trees with a fungicide in late fall and winter.
- Treat just after leaves have fallen, usually late November or December.
- A second application in late winter just before buds swell is advisable, especially in areas with high rainfall or during wet winters.
- Don’t apply fungicides during the growing season, because they won’t be effective.
Choose effective fungicides.
- The safest effective products available for backyard trees are copper soap (copper octanoate) or the fixed copper fungicide—copper ammonium.
- Apply either of these copper products with 1% spray oil to increase effectiveness.
- Bordeaux mixture is a home-made copper sulfate and lime mixture that must be carefully mixed up just prior to treatment. For a recipe, see Pest Notes: Bordeaux Mixture.
- The synthetic fungicide chlorothalonil is also effective.
Make fungicide applications effective and safe.
- The fungal spores that cause the disease germinate in the spring and spend the winter on twigs and buds.
- When you spray a fungicide, thoroughly cover all branches and twigs until they are dripping so all spores are killed.
- All peach leaf curl fungicides have environmental and health risks. Wear protective clothing, and follow label directions to stop drift or runoff.
- After many years of use, copper ions from copper- based fungicides can accumulate in soil. This can harm soil microorganisms and, through runoff, aquatic organisms. Take care when using these materials to avoid excessive runoff.
Minimize the use of pesticides that pollute our waterways. Use nonchemical alternatives or less toxic pesticide products whenever possible. Read product labels carefully and follow instructions on proper use, storage, and disposal.