2021 Fall Control for Coryneum Blight & Peach Leaf Curl
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2021 Fall Control for Coryneum Blight & Peach Leaf Curl
Landscape & Garden Treasure Valley
Coryneum blight (Thyrostroma carpophilum) & Peach leaf curl (Taphrina deformans)
Posted on: November 1, 2021 by Nic Usabel
Coryneum blight or commonly known as shothole disease which is caused by fungus Thyrostroma carpophilum. Trees which have been affected develop small, round, tan-to-purpleish spots which then dry and fall out of the leaf producing a shothole effect. Most cultivars of peach, nectarine, apricot, and almond are very susceptible while cherry and plum are less susceptible. In addition, ornamental plant species can show damage. Beyond the leaf, symptoms can also be seen on the current season and 1-year old fruiting wood. Infections consist of round, reddish spots which are slightly sunken.
Chemical control will occur after 50% leaf drop in late autumn by spraying with a copper-based fungicide, chlorothalonil, or Bordeaux mixture. Follow the label instructions for rate and application procedure. Prune out affected twigs when practical. Culturally control shothole disease by not allowing irrigation sprinklers to wet the tree foliage, select cultivars which are disease resistant when available, and remove and dispose of affected foliage and twigs.
Peach leaf curl caused by fungus Taphrina deformans and is specific to peaches and nectarines. Trees that are infected will have leaves that are distorted or curl, appear blistered, and develop a yellow or red color.
Control can be achieved by a single fungicide application in the fall after 90% of the leaves have fallen. Chemicals used for control are copper products or chlorothalonil. Follow the label instructions for rate and application procedure. Homeowners should also remove and dispose of infected leaves that have fallen to the ground, to remove as much inoculum as possible. Resistant varieties can be selected for additional cultural control.
References:
- Peach Leaf Curl, PNW Handbook
- Peach Leaf Curl Disease, Utah State University
- Shothole-Peach, PNW Handbook
- Shothole, UC IPM
