Description
    Target leafspot, also known as bull's eye or zonate leafspot, is a recently discovered disease on black walnut. So far it has been reported on black walnut only in Illinois and Ohio.

    The disease causes characteristic circular spots on the foliage with dark brown concentric rings inside each spot. These spots strongly resemble small targets, hence the name.

Injury
    The disease progresses rapidly in black walnut. The leaf spots fuse together, causing an entire leaf to curl up, turn brown, and fall from the tree. Symptoms first appear early in August. Within only a few weeks the entire tree may be defoliated.

    The disease causes premature defoliation, thus reducing the tree's growth, vigor, and resistance to other stress factors.

Control
    No control has yet been developed. Fertilization with nitrogen should help minimize some of the harmful effects.