Pezicula malicorticis (H. Jacks.) Nannf
Branch lesions first appear as small, circular spots that are purple or red when wet. As lesions enlarge, they become elliptical, sunken and turn orange to brown. A distinct margin develops between healthy and diseased tissue, which eventually causes the bark to crack around the infected area (A). The infected bark tissue over the canker separates into small pieces and curls upwards from the lesion. On older cankers, the bark sloughs off leaving only the last fibers behind. These fibers run lengthwise across the lesion and their appearance as such has often been referred to as "fiddle strings". Anthracnose cankers typically do not enlarge during their first year of growth.
Uncommon in the east, but has been reported in Canada, MI, and some New England states.
Can be confused with other cankers.
While pesticide applications may reduce the spread of cankers, they are not effective at eradicating existing cankers. It is better to prevent new cankers by removing existing cankers as inoculum sources and following good horticultural practices to promote tree vigor, such as following a good fertility program and ensuring adequate water drainage.
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