Leaf infected with Peach Leaf Curl. Photo Credit: POP

Peach leaf curl (Taphrina deformans) is a highly common fungal disease that affects peaches and nectarines. 

Lifecycle: The fungus overwinters on the surface of infected twigs and spreads on water droplets in spring during temperatures ranging from 50-70 degrees from bud swell to bud break. In the summer and fall, dried spores on leaves are carried on the wind to overwinter on branches. 

Signs and Symptoms: Peach leaf curl causes leaves to thicken, pucker, and curl turning from reddish to yellow to gray and then falling off. It can sometimes cause disfigurement and drop of fruit, but this is less common. Once spotted in spring, it is too late to treat the fungus until the dormant season. 

What’s going on with an infected tree: The tree is in a weakened, under-resourced state. The fungus is disrupting the tree’s ability to photosynthesize so it has less resources than normal. Additionally, the fungus often causes the tree to drop infected leaves, and grows new ones requiring more than normal resources. If the tree continues to be significantly under-resourced for several years in a row, it could weaken and die. 

What you can do to support an infected tree: (check out POP’s Peach Leaf Curl action plan!)

  1. Infected trees often drop infected leaves and regrow new ones causing a need for plenty of nitrogen. Spreading compost or applying fish emulsion can help. Apply holistic sprays such as compost tea, Effective Microbes, and/or neem oil to boost tree immunity every two weeks from late March to early May. 
  2. When fruitlets on stone fruit such as peaches are about 3/4 inch, thin fruitlets to increase light and air circulation and reduce rate of infection from fruits too closely touching.  Peaches should be thinned about 8″ apart (if you have squirrels, thin to 4″). You can read more about thinning on the POP blog. Infected trees are weakened and they’re fruit load should be thinned in correlation to the severity of the infection to protect the trees resources. 
  3. Don’t allow tree to become water stressed. If rain accumulation is less than 1”/week supplement with irrigation. 
Heavy peach leaf curl infestation on new leaves. Photo Credit: POP

Dormant season spray 

Spray a copper fungicide like Cueva or biofungicide like Serenadeafter leaf drop up to bud swell. Spray trunk and branches thoroughly, until dripping to ensure sufficient coverage. Please read labels carefully before application. 

Copper fungicide is highly effective, but harsh spray that also damages beneficial microbes. Cueva is a newer spray option with a lower copper content. It is recommended to follow copper sprays with applications of compost tea to help rebuild a healthy soil and tree microbiome.

Biofungicides that may help with Peach Leaf Curl include Serenade, Regalia, and Double Nickel. You can read more about biofungicides on the POP Blog. 

Note: Copper and biofungicide applications are a preventative measure that are only effective applied during the dormant phase and cannot be applied to already injured fruit or leaves.

This POP Blog was written by Education Director Corrie Spellman-Lopez.

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