Dark spots on Green Ash leaves - Ask Extension
Could you please help us identify what is causing the dark spots on our Green Ash tree leaves? We have two large Green Ash trees we have been treatin...
Knowledgebase
Dark spots on Green Ash leaves #868855
Asked May 17, 2024, 11:04 AM EDT
Could you please help us identify what is causing the dark spots on our Green Ash tree leaves? We have two large Green Ash trees we have been treating for Emerald Ash Borer, but both are starting to show signs of stress. Both trees have had Anthracnose for several years, but this year and last, the leaves have dark spots and both trees drop many of these affected leaves. What ailment is causing this and do we need to be careful about disposing of these leaves so as not to infect other trees? Thank you!
Hennepin County Minnesota
Expert Response
There are several fungal diseases which can cause black spots. Anthracnose is one. Unfortunately I can't diagnose your tree from a couple of photos. If you've been treating your tree for EAB, you are possibly working with a certified arborist. If not, I suggest you contact one to continue the treatments and manage whatever this disease is. Look here:
https://www.treesaregood.org/findanarborist/arboristsearch
Here are a couple of possible culprits for these spots:
https://bygl.osu.edu/node/413
https://extension.umn.edu/plant-diseases/anthracnose-trees-and-shrubs
Also, see here:
https://extension.umn.edu/plant-diseases/leaf-spot-diseases-trees-and-shrubs
https://www.treesaregood.org/findanarborist/arboristsearch
Here are a couple of possible culprits for these spots:
https://bygl.osu.edu/node/413
https://extension.umn.edu/plant-diseases/anthracnose-trees-and-shrubs
Also, see here:
https://extension.umn.edu/plant-diseases/leaf-spot-diseases-trees-and-shrubs
