How to Manage Pests

Pests in Gardens and Landscapes

European canker—Nectria galligena

European canker can infect both apple and pear trees. In California, this is a minor pest. Reddish brown lesions develop around infected leaf scars on young shoots or spurs. Concentric ridges develop around the sunken areas of dead tissue. The bark over the diseased area cracks and the edges may take on a papery appearance.

Life cycle


European canker is managed primarily by pruning and by using protectant fungicides. Prune and destroy diseased wood early in summer. In apples, some varieties are more susceptible than others. If trees are infected with European canker, apply a freshly prepared Bordeaux mixture or a fixed copper material at label rates during early leaf fall, before rains begin. Where the disease is serious, make a second application when 0.75 of the leaves have fallen. Timing of sprays is critical. Treatments are particularly necessary when warm fall weather causes a prolonged leaf fall.

Canker encircling terminal part of twig
Canker encircling terminal part of twig

Canker  around leaf scar
Canker around leaf scar

Statewide IPM Program, Agriculture and Natural Resources, University of California
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