Peach leaf curl
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Peach leaf curl has become an important disease in Michigan. This disease of peach and nectarine can defoliate trees. Infections take place in the spring as the buds open. The fungus infects peach buds from bud swell to bud opening under wet conditions. Air temperatures between 50 to 70°F are ideal. Rain or dew moves spores into the opening bud allowing the infection of young tissue. Prolonged cool, wet periods during bud burst can result in severe infections. Effective controls include Bravo, Ziram, Ferbam (Carbamate) and copper compounds. Copper compounds have the benefit of providing some suppression of bacterial spot as well.
Early spring applications at or before bud break are effective in controlling this disease. Later applications can reduce the severity of the disease. Once leaves are infected, there is no effective fungicide treatment. The leaves are infected in the bud and once they have emerged they are not susceptible to infection. Infected leaves become thick and crinkled, turning orange or red. When the fungus sporulates, the leaves become powdery with spores. Infected leaves will eventually fall off. The tree will grow new leaves. Peach leaf curl weakens the tree by removing leaves during early growth. This reduces the size of the remaining fruit. Heavy fruit thinning will reduce stress on the tree and increase the likelihood of a marketable crop. Severely infected trees should receive an increased ration of nitrogen fertilizer. This will help maintain vigor and help replace lost leaves.