Black Knot
Apiosporina morbosa
fungal disease.
Fungal disease producing characteristic black warty galls on plum and cherry branches.
Biology and conditions
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Symptoms
- Black hard warty galls on branches
- Branch dieback above galls
- Increasing gall size over years
Controls
- Prune galls 4 inches below visible margin in dormant season
- Burn or bury removed material
- Fungicide at bud break
- Remove wild plum and cherry hosts nearby