Black scales on plum trees

Asked March 15, 2019, 9:34 AM EDT

Please tell me what the black crusty patches are on the plum trees. The trees are growing behind a vacant home and it had been producing fruit. Last summer, I noticed the trees were covered with crusty patches and was no longer bearing fruit. What is it?

Wayne County Michigan

1 Response

My best guess without a picture is that the plum trees have black knot a serious fungal disease affecting plums and cherries. Here is a link to an article I wrote.
Here is another