Knowledgebase
Plum tree #931709
Asked May 14, 2026, 2:31 PM EDT
Allegan County Michigan
Expert Response
Hello,
This is black knot. You can read this article on managing black knot:
https://www.canr.msu.edu/news/controlling_black_knot_in_michigan
Black knot will eventually kill trees, but by pruning it out (especially in winter) you can keep the tree alive for many more seasons. Make sure to sanitize your equipment in between cuts.