Our ash tree is dropping it's leaves

Asked July 17, 2017, 9:44 AM EDT

Hi, We had our ash tree treated for Emerald Ash Bore on July 5th~about a week later it began to drop leaves and now our yard surrounding the tree is littered with leaves and they are dropping like snowflakes. The company that treated the tree is coming out this week to look at it but are blaming it on "anthracnose". What I am reading on-line is that anthracnose affects the tree in the spring, makes it drop leaves in the damp, cool spring and often grows new leaves out again mid-summer. The tree began dropping leaves so shortly after the ash bore treatment that I am concerned the company used the wrong treatment on the tree. I also have read that maple trees are affected by anthracnose and we have a maple tree just 15 feet, or so, away from the ash tree. Both trees are mature and quite large. The maple tree is looking very good. I have collected leaves from the ash tree if they can be analyzed for chemicals. Thank you for your help!

Hennepin County Minnesota emerald ash borer anthracnose horticulture

1 Response

I do not know of any EAB treatment that would cause the symptoms you described, especially so suddenly. There are two kinds of EAB treatments: injections and systemic drenches. Injections create holes in the trunk which could potentially be a pathway for pathogens. What is known for certain is that untreated ash trees in EAB infested areas will die.
https://www.mda.state.mn.us/~/media/Files/plants/eab/eabtreatmentguide2.ashx

Ash anthracnose is fairly common in general, and seems especially so this year. Symptoms can occur this time of year, although the infection might have occurred earlier. The pathogen that causes it is not the same as the pathogen that causes anthracnose in maples, although the environmental conditions leading to infections are much the same.
https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/anthracnose-of-ash-trees/
https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/anthracnose/

Without seeing good quality photos, I can't go much beyond what I've said. If you think your tree service misapplied pesticides, or you think the leaf drop is something other than anthracnose, I suggest you contact a certified arborist to get a second opinion:
http://www.isa-arbor.com/findanarborist/arboristsearch.aspx