Peach leaf curl is a fungal infection of peaches which can cause defoliation and loss of the crop, depending on how severe it is. Fortunately, this fungal infection can be treated, and there are ways to deal with an already existing case of peach leaf curl so that the year isn't a total waste. Peach leaf curl is quite common in some parts of the world, and sometimes working together with neighbors who also have peaches is a good idea, to ensure that all of the trees in a small area are protected and treated so that they do not infect each other.

This condition is caused when a peach tree is colonized by a fungus known as Taphrina deformans. The spores of the fungus work their way into the leaf buds in the early spring, and when the peach tree starts to leaf out, the fungus goes to work. A tree afflicted with peach leaf curl will have heavily distorted leaves which typically turn red or yellow while curling, clubbing, and eventually dropping off. The fungus can also attack the fruit, rendering it inedible or preventing it from maturing.

If a tree manifests signs of peach leaf curl in the spring, it should be treated with extra nitrogen to reduce the stress on the tree, and some gardeners also recommend routine heavy watering to eliminate drought stress. By reducing stress, gardeners increase the chance of saving the peach crop. It is also a good idea to thin the young peaches out more than usual, so that the tree can dedicate resources to producing a smaller crop of really good peaches, rather than a larger crop of mediocre ones.

After the leaves of a tree with a case of peach leaf curl drop off, they should be raked up and burned, as the spores of the fungus could otherwise overwinter and infect the tree again in the spring. Then, the tree should be treated with a copper-based fungicide to kill the spores. Some gardeners like to treat in the fall and then again in the spring, right before the tree buds out, ensuring that the spores are truly eliminated.

Care is advised when using fungicides. They should never be used around crops which are going to be picked for food, as many fungicides can adversely affect human health. It is also a good idea to protect plants underneath and near the peach tree, as fungicides can damage some plants, especially flowers. Facial protection for the nose, mouth, and eyes should be worn while applying fungicides, and pets and other members of the household should be kept out of the area until the application is over.