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Nectria canker

Nectria galligena Bres. in Strass.

Cankers are often associated with nodes, often appearing as elliptical sunken areas (A). Sometimes callus production stops fungal invasion and cankers die by season's end. Other times, the fungus, walled off by callus formation during the current growing season, re-invades callus tissue when active growth resumes the following season, giving older cankers a zonate or target-like appearance (B). Enlarging cankers girdle infected twigs and branches, killing tissue above cankers. During damp weather, gelatinous white to cream-colored sporodochia produce spore masses that ooze from cankers; bright red to orange fruiting bodies (perithecia) may appear on older cankers (similar to Nectria twig blight).

Distribution

Common to northeastern US and southeastern Canada and westward, but problems usually persist only in maritime climates or where infected nursery stock was planted.

Similar Species

Can be confused with other cankers, but the appearance of the colorful sporodochia helps to distinguish this disease from similar cankers.

Management

The disease is common in cold pockets and on poorly drained soils. Where it occurs at relatively high elevations, it is most common on exposed slopes with shallow or infertile soils. While pesticide applications reduce the spread of cankers, they are not usually effective at eradicating existing cankers. It is better to prevent canker establishment by removing existing cankers and following good horticultural practices, such as maintaining a good fertility program.

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