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.

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.