Phoma canker

Phoma complanata

Symptoms. If present, leaf spots are circular, brown, and often have yellow halos. As disease develops, leaf spots coalesce and result in a general yellowing, necrosis, and blighting of foliage. Pycnidia appear in leaf lesions about two weeks after infection. Dark brown to black lesions may develop on petioles, resulting in leaves that twist and bend over. Large, dark brown to black cankers form on parsnip crowns and on the sides of taproots. These cankers can enlarge and affect much or all of the crown tissue. Cankers result in splitting or cracking on the upper portion of the root. Careful examination of the surfaces of cankers will reveal pycnidia embedded in these tissues. Pycnidia ooze a white or creamy spore exudates. Affected roots are reported to have a sweet cinnamon odor.

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