Common Names: Perennial target canker, Nectria canker
Syn. Neonectria galligena. A fungal plant pathogen which causes cankers that can kill branches of hardwood trees by choking them off. Old cankers are easily recognized because of their typical target shape, caused by rings, each of which represents a year's growth of callous tissue around the infected area. Young cankers are not as easily recognized because overgrown callous tissue may hide the affected area. Tiny, red fruiting bodies of the Nectria fungus may be present around the diseased area. Cankers usually occur on the main stem of the tree, often at a point where a branch broke off and left an open wound. Nectria canker results in defects in the wood, stunting of growth, or death (if the canker becomes large enough to girdle the stem). Trees may also break at canker locations during high winds. It is believed to infect: yellow birch, sassafras, paper birch, northern red oak, red maple, beech, bigtooth aspen, and black walnut trees. Possibly others as well.