Over the past month, the DuPage and Kane Counties Extension office has received several calls and emails regarding peach leaf curl. Given the wet spring conditions, it is not surprising that this fungal disease is showing up in orchards this year. However, early symptoms can easily be mistaken for frost damage, as both can cause leaf distortion.
Peach leaf curl is relatively easy to distinguish from other fungal diseases once symptoms become more pronounced. Infected leaves appear thickened, curled, or crinkled, often with scalloped edges and a characteristic pinkish-red discoloration in affected areas. As the disease progresses, leaves may turn yellow and prematurely drop, and in severe cases, entire trees can become defoliated.
Sadly, by the time symptoms are visible, it is generally too late to effectively control the disease for the current growing season. Management strategies are most effective when implemented during the dormant period. Fungicide applications are typically recommended in the fall, after leaf drop, or in early spring before bud swell. However, during warm springs, timing spring applications can be challenging, as buds may swell earlier than expected. A properly timed application of a copper-based or chlorothalonil fungicide in the fall is usually sufficient to reduce disease pressure the following season. Planting resistant cultivars is another valuable management strategy; for example, ‘Redhaven’ and related cultivars offer good resistance to peach leaf curl.
Maintaining overall tree health is essential when managing peach leaf curl. Good cultural practices can help trees recover and remain productive. This includes following a balanced fertilization program, providing adequate irrigation, aiming for about one inch of water per week during dry periods, and thinning fruit to reduce stress and crop load. Strong, healthy trees are better able to tolerate and recover from disease pressure.