Affected leaves drop from the trees, giving the tree a very thin canopy, even though surrounding trees look healthy. The disease is particularly damaging to peach fruit. A simple control measure is to spray a fungicide on trees that have this problem. There is no rescue treatment during the growing season. The idea is to kill the fungus as it overwinters on the twigs and bud scales.
Thorough coverage is essential.
This year, several homeowners complained that sprays had not prevented this disease. I have not found any information indicating that the fungicides are failing in other locations or that the fungus has developed resistance to the fungicides. It is likely that the chemicals used did not adequately cover the entire tree or that they were not agitated during the spray process. Some chemical options registered for peach leaf curl include Spectro by Cleary, bordeaux mix, copper fungicides, lime-sulfur, and sulfur. Many of these chemicals, especially bordeaux, are difficult to keep mixed, and sprayers often become clogged with chemicals.