Black knot on Salix or Alnus???

Asked February 22, 2020, 5:48 PM EST

I did not plant these shrubs so I am afraid I can't offer a good ID (the catkins led me to say Salix or Alnus...) but they are showing significant fungal infection which appears to be black knot. I thought only prunus varieties were susceptible? Should these plants be destroyed??

Westchester County New York

1 Response

Hello,

The black growth on the alder is a thick sooty mold associated with the woolly alder aphid. See link for more info and pictures. https://bygl.osu.edu/node/1415

Regards,
Carol Quish
UConn