How Do I Treat Peach Leaf Curl Before It Starts?
You prevent peach leaf curl with a single dormant-season fungicide spray applied before the buds swell in late winter. Once you see the puckered, reddish leaves, it is too late to treat that season.
Peach leaf curl is caused by the fungus Taphrina deformans, and it affects peaches and nectarines across Santa Cruz County every year. The key to control is timing. UC IPM's peach leaf curl guide recommends applying a copper-based fungicide (fixed copper or Bordeaux mixture) once in late November to December after leaf drop, or once in late January to early February before buds begin to swell. One well-timed application is usually enough for the season. If your tree had severe curl last year, apply twice: once after leaf drop and again before bud swell.
In Santa Cruz, the timing depends on your microclimate. Trees in warmer spots like the Pajaro Valley or Scotts Valley may start pushing buds in early February, so spray by mid-January. In cooler, foggier areas, you often have until late February, but earlier is always safer. Watch your buds closely: once you see any green or pink showing at the tips, the window has closed.
Spray on a dry day when no rain is forecast for at least 24 hours. Cover all branches and buds thoroughly. Copper fungicide is approved for organic gardens and widely available at local nurseries. Avoid spraying when trees are in full leaf, as copper can damage foliage.
For long-term management, some peach varieties show natural resistance. Frost, Indian Free, and Q-1-8 are noted for better tolerance, though no variety is completely immune.
This week: Check your peach and nectarine trees. If the buds are still dormant and tightly closed, apply a copper fungicide spray now. Mark your calendar for next November as a reminder.
Our free Seasonal Tasks Checklist includes dormant-season spray timing for fruit trees so you do not miss the window. For more on fruit tree care, see When Should I Plant Bare-Root Fruit Trees in Santa Cruz.
