Tree Fungicide - How can I treat it??

Asked March 6, 2020, 5:43 PM EST

I have attached 3 pictures of my neighbors tree (species unknown) that has an advanced stage of fungus on many of its branches. This same fungus has now invaded my purple leaf plum - less severe than attached pics, and I am concerned about how to combat it - treat/save the tree. Thank You!

Anne Arundel County Maryland

1 Response

This looks like black knot fungus on the branches. It 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.