The appearance of puckered, discolored leaves on a peach or nectarine tree is a common and frustrating sight. This issue, known as Peach Leaf Curl (PLC), is a fungal disease. While it is a natural impulse to remove the affected foliage, leaf removal is largely ineffective at this stage. This article provides advice on the actions necessary for the long-term health of your tree.
Understanding Peach Leaf Curl
Peach Leaf Curl is caused by the fungus Taphrina deformans, primarily affecting peaches and nectarines, and occasionally almonds and apricots. Visible symptoms begin in the spring as new leaves emerge. Infected leaves become severely distorted and thickened, often displaying a prominent puckering or blistering effect.
The color of the affected tissue changes from pale green to shades of yellow, red, or purple. As the disease progresses, thickened areas develop a grayish-white, velvety coating, which is the fungus producing spores. These deformed leaves eventually turn brown, shrivel, and fall prematurely, sometimes causing significant defoliation.
The critical detail about PLC is that infection occurs much earlier than when symptoms appear. Infection happens in the spring when leaf buds are just beginning to swell and open. The fungus requires cool, wet weather (typically 50°F to 70°F) for spores to germinate and enter the young tissue. Once the fungus has invaded the leaf, the resulting damage is irreversible, and no treatment applied during the growing season can correct the current symptoms.
The Efficacy of Leaf Removal
Removing curled leaves is generally not recommended for established infections. By the time the leaves are visibly damaged, the damage for the current season is already done. Furthermore, the fungal spores responsible for next year’s infection have likely already been produced and spread onto the tree’s bark and buds. Removing leaves at this stage does nothing to stop the current outbreak.
Focusing on removing every curled leaf is a labor-intensive effort that provides little benefit for disease control. Aggressively stripping the tree of its foliage is detrimental to its health. Leaves are the tree’s energy factories, and excessive removal significantly reduces the tree’s ability to photosynthesize and create the carbohydrates needed to grow fruit and recover.
A tree that loses many leaves due to PLC will naturally attempt to produce a second flush during the summer, provided the weather turns warmer and drier. This second leaf production draws heavily on the tree’s stored energy reserves, weakening it and making it susceptible to other stresses, such as winter injury or secondary diseases. Removing additional leaves only compounds this stress by forcing the tree to expend more energy on recovery.
Removing a few infected leaves from a very young tree with a minor infection is sometimes suggested for marginal sanitation, but this is not a substitute for proper disease management. For a mature tree, the best course of action during the growing season is to allow the tree to naturally shed the damaged leaves. Focus instead on providing good cultural care, such as proper watering and fertilization, to support its recovery and the growth of the second, healthy set of leaves.
Timing is Everything: Preventing Future Infections
Since removing affected leaves is ineffective, the solution to Peach Leaf Curl involves a preventative strategy targeting the fungus during the dormant season. The fungus overwinters as yeast-like spores on the surface of the tree, specifically in the crevices of the bark and around the bud scales. These overwintering spores are the source of infection for the following spring.
To break this cycle, apply a protective fungicide when the tree is dormant, before the new leaf buds begin to swell. Timing is critical: the fungicide must be on the bark and bud scales to kill the overwintering spores before new tissue emerges in spring. Once the buds swell, it is too late, as the fungus has already entered the protective layers of the bud.
A single, thorough application of a copper-based fungicide (such as copper soap or fixed copper) or a product containing chlorothalonil offers the best control. This application should occur in the late fall after all leaves have dropped or in late winter/early spring before any sign of bud swelling. In areas with high rainfall, a second application later in the dormant season may be necessary for complete coverage. This proactive, preventative treatment during dormancy is the only proven method for managing Peach Leaf Curl and protecting your tree from future damage.