Caused by the fungus Taphina deformans, it commonly affects peach and nectarine trees. Cool, wet weather activates the pathogen spores. This usually occurs when leaves are just beginning to unfurl. It is the bane of many a home orchardist.
Infected leaves detach from the tree and fall onto the ground. They contain a source of innoculm and should be removed from the site to help reduce future spread. New leaves will grow but they too can become infected if late season rainfall events occur. In many cases the disease significantly reduces fruit production. Summer pruning will help reduce inoculum load.
Treatment protocol calls for three foliar spray applications of copper based fungicide. November, right around Thanksgiving, and in winter, just before Valentine's day and finally, just before bud break.
Peach Leaf Curl
Treatment success varies. In the past, lime sulphur or fixed copper formulations were both effective and available. These fungicide formulations are no longer available and have been replaced by a weaker copper based fungicide. During the winter/spring seasons of 2023 and 2024, uncontrollable outbreaks occurred statewide. Rainfall events were steady and continued late into spring. In most cases, treatments were not effective. Even peach trees bred for resistance became infected. Sometimes you have to accept that mother nature is in charge and do the best to support tree health, which will help with disease resistance.