Peach Leaf Curl is a fungal disease that infects the leaves, blossoms, fruit, and shoots of peaches and nectarines. It causes the leaves to curl up, die, and fall off the fruit tree. It can lead to premature defoliation, less flowering, and less fruit production.

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Cause

  • A fungus that infects the leaves, blossoms, fruit, and shoots of peaches and nectarines

  • Overwinters in the leaf bud and on the shoots

  • Can spread from tree to tree, mainly by wind or precipitation

Symptoms:

Leaves begin to curl up, die and fall off the tree

Timing:

  • Observed from May to June

  • Requires cool and wet weather

  • Ideal temperatures for infection are 50°F to 70°F° (16-24°C) at humidity levels above 95%

How to Avoid:

  • All peaches are susceptible so a spray program is recommended (See “How To Treat”)

  • Prune trees to an open structure

  • Sanitize pruning equipment between trees

How to Treat:

  • When peach leaf curl is discovered, little action can be taken until dormancy. Once dormant, sulfur and copper fungicides should be sprayed in November after leaf fall and again before bud break around mid-February.

  • To help infected trees recover, thin the fruit so the tree can focus on producing new leaves. With severe infections, it is recommended that all remaining fruit be removed so the tree can put all energy toward new leaf production.

  • Aid leaf decomposition in the fall by mowing and spraying leaf litter with nitrogen fertilizer.

Why it Matters:

  • Peach leaf curl can lead to premature defoliation, less flowering, and less fruit production.

  • Peach leaf curl rarely kills a tree by itself but contributes to weakening the tree and increasing susceptibility to other diseases.

  • After an initial outbreak, preventative measures will need to be taken every year for peach leaf curl.

Sources: MyIPM, Pennsylvania State University Extension, Kansas State Research and Extension, University of California IPM, Michigan State University Extension, Patrick L. Byers, Horticulture Specialist, and Michael Phillips, “The Holistic Orchard.”