Peach Leaf Curl Control - Solution Guide
Peach leaf curl (a.k.a. leaf curl) is a disease caused by the fungus Taphrina deformans. The species name Deformans refers to the curled, blistered, or tumor-looking leaf growths the fungus creates on the foliage. However, the fungus can affect the blossoms, fruit, leaves, and shoots of peaches, ornamental flowering peaches, and nectarines, and it is one of the most common disease problems for backyard growers.
Symptoms & Effects
- This fungus survives the hot, dry summer on the tree's surfaces.
- Peach leaf curl is a cumulative disease, just like many fungal diseases.
- When the weather turns cool and wet in fall, the dormant spores germinate into growing spores. The spores continue to increase in number, and eventually, a film of spores is formed on the tree's surface. The following spring, those spores can move by wind, splashing water from irrigation or rain to infect new leaves, and the cycle continues if it's not interrupted.
- Once leaf curl outbreaks are noticed in the spring to early summer, it is too late to spray for prevention. However, thorough sanitation can help prevent future outbreaks. Picking off symptomatic leaves and raking up infected fallen leaves is essential while the tree is in leaf. Fungicide applications come into play after trees have gone dormant in the fall to early winter and early spring.
Favorable Conditions
Peach leaf curl prefers periods of cool, wet weather when spring leaves are first opening on the tree. The optimum temperature for this fungal growth is around 68°F, and the minimum is 48°F, with the maximum temperature for development in the high 80°F. Spore germination, then spore growth, occurs during periods of high humidity. For infection, moisture from rain, dew, or irrigation for more than 12 hours at temperatures around 60°F is needed.
Control & Management
For non-resistant varieties, treat trees with a fungicide every year after leaves have fallen. Generally, a single early treatment when the tree is dormant is effective, although in areas of high rainfall or high relative humidity, particularly during wet winters, a second application is advisable during the late dormant season. Time for the late-season fungicide application when flower buds begin to swell but before green leaf tips are visible.
A copper-based fungicide like Bonide® Copper Fungicide or Bonide® Liquid Copper Fungicide is best for controlling leaf curl. Again, spray the entire tree with properly mixed product after leaves have dropped in the fall and re-apply in the early spring, just before the buds open, for persistent Leaf curl issues. For the best results, trees should be sprayed to the point of runoff or dripping.
