How to Manage Pests

Pests in Gardens and Landscapes

Seasonal development and life cycle—European canker

The fungus that causes European canker, Nectria galligena, survives the summer as mycelia in shoot and branch cankers. Cool, wet weather in fall and winter stimulates the formation of spore-bearing structures on cankers. Spores are moved by splashing rain and commonly infect leaf scars on young shoots and spurs. Leaf scars are most susceptible to infection during the first hour after leaf fall.

Once infection takes place, the fungus slowly penetrates bark tissue. Lesions become apparent 2 to 3 months later. Cankers are formed and may encircle and kill twigs and small branches. The fungus may cease activity when the weather warms up and then resumes development when conditions that favor it return.

Spores on the surface of cankers
Spores on the surface of cankers

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