Peach Leaf Curl

If you see red, puckered leaves on peach, nectarine, or almond trees, it’s probably peach leaf curl.

Peach leaf curl can seriously reduce the leaf canopy, cutting the number of leaves available for photosynthesis. The Taphrina deformans fungus costs U.S. orchardists approximately $2.5-3 million in losses annually.

Fungal spores stay on tree surfaces year-round as ascospores. When spring rains or poor drainage occur, the spores germinate, forming blastospores that attack vulnerable new growth.

Peach leaf curl on nectarine leaves

Symptoms of peach leaf curl

Red, blistered leaves that tend to twist and curl are a sure sign of peach leaf curl infection. Like the initial signs of Eugenia psyllid infestation, peach leaf curl damage progresses down twigs and stems, into the trunk, significantly reducing fruit production.

As infected leaves mature, they become thicker and rubbery. Leaves turn from green to purplish-red to white. Infected leaves fall early, as well. If you cut into the wood, the vascular bundle will be discolored, showing where the fungal spores are reproducing. Red lesions may also occur on the fruit. 

Peach leaf curl treatment

Once peach leaf curl takes hold, all you can do is treat it with fungicides each autumn after the leaves have dropped. Those leaves should be removed and destroyed. Effective fungicides include fixed copper and Bordeaux mixture. For non-organic growers, chlorothalonil is the only effective non-copper fungicide. Chlorothalonil is a carcinogen that can damage your kidneys, so I don’t recommend it. Heavy infestations may require a second treatment as buds swell before leaves become visible.

Unfortunately, long-term copper use can result in a toxic build-up in the soil. [Yet another argument for getting regular soil tests.]To help an infected tree during the summer, thin the fruit later in the season to minimize points of entry for further infection.

It was once a common practice to remove the affected leaves in spring. Research has not shown this to be effective at combating the disease or helpful to the tree. Removing too many leaves reduces photosynthesis and can lead to sunburn damage. If you must remove infected leaves, sanitize your tools between each cut with a household cleaner, or you may spread the disease further. Also, protect exposed limbs by whitewashing them with a 50:50 solution of water and white latex (not enamel) paint.

​Severely damaged trees may need additional nitrogen later in the growing season.