Please help me identify the fungus pictured in the attached photos on my plum...

Asked August 25, 2013, 9:37 PM EDT

Please help me identify the fungus pictured in the attached photos on my plum tree (20'H x 25'W) in my back yard and what may have caused it.

Montgomery County Maryland

1 Response

Your plum tree has black knot. Black knot affects plum and cherry trees and is caused by a fungus. The best thing to do is to prune out the galls, cutting several inches below the knot. You may refer to the following publication for more information. LW http://ohioline.osu.edu/hyg-fact/3000/pdf/HYG_3011_08.pdf