black knot on a plum tree

Asked April 21, 2020, 2:38 PM EDT

Can you advise me about how to treat the black knot on my plum tree? I read it is a fungus.

Baltimore County Maryland

1 Response

Black knot is a disease of plants in the Prunus genus (plum, cherry, etc.). It can affect edible and ornamental plum trees alike.
https://extension.umd.edu/hgic/topics/black-knot-trees

Chemical controls for black knot are not very effective once the black galls are present. You can prune out infected stems and branches 4 to 6 inches below the galls and remove the clippings from the landscape. If the disease has progressed too far in the tree, you may have to consider replacement.

Marian