Japanese Red maple

Asked September 3, 2016, 6:22 PM EDT

This tree has been thriving on the south side of my Roseville house for ~ 10 years, minus deer browsings. Within the last Month I've noticed leaves on individual small branches wilting , drying & turning brown , now also happening on larger branches . any thoughts are welcome . thank you

Ramsey County Minnesota

1 Response

Thank you for the question. How lucky to have a Japanese maple survive so long in our zone 4b! That being said, it does look like it's having trouble. The first thing that comes to mind is verticillium wilt, a soil borne fungus that is common among some trees like maple. Fungicides are ineffective. Other causes for what you are seeing could be herbicide damage that may have drifted in, mechanical factors like weed whip injuries, and adverse environmental conditions (too hot, too dry, etc.). A sign that may may help tip the diagnosis in the direction of verticillium is streaking of the wood. On a branch that has died, peel back the bark and check for streaks. It is risky to make a diagnosis on the basis of photos, so read more about it in these publications:

If it is verticillium wilt, the tree may recover and then experience bouts of recurrence or the disease may move through the plant quickly, killing it. What you can do now is to remove the dead branches and discard in the trash to avoid spreading the diseases. Water well until the ground freezes and mulch around the base of the tree, keeping the mulch away from the trunk.
You might consider sending a sample to the University Plant Diseases Clinic: http://pdc.umn.edu/

Good luck with your tree and thank you for contacting Extension.