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Peach leaf curl is a fungal disease that affects only peach and nectarine trees. Distorted, reddened foliage in the spring is a distinctive symptom. Newly emerging leaves and shoots thicken and pucker and later may die and fall off. A leaf curl infection that continues untreated for several years will contribute 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 will not be effective.
Look for leaf curl symptoms in spring. |
- New leaves and shoots redden and pucker. Leaves may yellow, be covered with powdery, gray spores, and 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. |
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Treat just after leaves have fallen, usually late November.
- Although a single treatment is sufficient in most areas, a second application in late winter or early spring just before buds swell may be advisable in areas or during winters with high rainfall.
- Don’t apply fungicides during the growing season, because they won’t be effective.
Choose effective fungicides. |
- Fixed copper fungicides such as tribasic copper sulfate or cupric hydroxide are easiest to use; apply with oil to increase effectiveness.
- Bordeaux mixture is a copper sulfate and lime mixture that you should carefully prepare just prior to treatment. For a recipe, see Pest Notes: Bordeaux Mixture.
- Although lime sulfur is very effective, you must handle it carefully, since it can injure eyes and skin.
- The synthetic fungicide chlorothalonil also is effective.
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Make fungicide applications effective and safe.
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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 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 dripping.
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. |
