USDA Forest Service

Forest Health Protection, Southern Region


USDA Forest Service
Forest Health Protection
Region 8
1720 Peachtree Road, NW
Room 816 N
Atlanta, GA 30309

Phone: (404) 347-7478
Fax: (404) 347-1880

United States Department of Agriculture Forest Service.

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caused by Neonectria galligena and N. magnoliae


Importance. - Neonectria canker is the most common canker disease of hardwood trees. It seriously reduces the quantity and quality of forest products. This disease usually does not kill trees, but causes serious volume losses. It is common on yellow birch, black walnut, and sassafras. It also occurs on aspen, red oak, maple, beech, poplar, and birch.

Identifying the Fungus. - The fungus can be identified by the creamy-white fruiting structures that appear on cankers soon after infection. It can also be identified by the pinhead-sized, red, lemon-shaped perithecia near canker margins after 1 year.

Identifying the Injury. - Well-defined localized areas of bark, cambium, and underlying wood are killed by the fungus. Concentric, annual callus ridges develop around the expanding canker, and bark sloughs off the older parts of the canker. After several years, the canker resembles a target.



Target-shaped nectria canker on walnut

Target-shaped neonectria canker on walnut.



Biology. - The fungus survives through the winter in cankers, and produces spores during the spring. Windblown and watersplashed spores infect tree wounds and branch stubs.

Control. - Cankering may be minimized in high value areas by avoiding wounds and pruning out branch cankers. Sterilize pruning tools before moving to an uninfected tree and conduct pruning operations during dry periods when spores are less abundant.




USDA Forest Service - Forest Health Protection, Southern Region
Last Modified: Monday, 16 December 2013 at 14:18:29 CST

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