Botryosphaeria dothidea (fungus)
Many woody plants, including redbud, rhododendron, crabapples and dogwoods.
This fungus causes cankers and branch dieback. Cankers, which may take a year or more to develop, are visible as sunken, brown-to-black areas on infected branches (top right photo). As branches are girdled by the canker’s spread, leaves wilt and die but remain attached to the branch (bottom right photo). Small, pimple-like fruiting bodies (pycnidia) may be visible in the area of the canker.
How it’s spread
Drought-stressed plants are much more susceptible to this disease. This fungus frequently enters and infects through wounds.
Keep plants well-watered during droughts. Affected branches may be pruned out. Many fungal cankers look similar; confirm your field diagnosis by sending a sample to MSU Diagnostic Services.
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