Description
    Perennial target canker, also known as Nectria canker, occurs on black walnut throughout its range, but seems to be more common in the Northeast and the southern Appalachians.

    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.

Injury
    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.

Control
    Cut infected trees and remove from the area, including other tree species that may also be affected: yellow birch, sassafras, paper birch, northern red oak, red maple, beech, and bigtooth aspen.