Wilting Japanese maple Might have Verticillium Wilt

Q: This Japanese maple gets afternoon sun. It is irrigated three times a week for ten minutes. Irrigation is shut off during rainy periods. Suddenly the leaves are wilting and falling. Is this verticillium wilt?. 

A: It could be verticillium wilt or maybe phytophthora root rot. Ether way, I think this is a poor watering = root health issue.

You wrote that the tree was irrigated three times per week but that doesn’t tell me how much water it got each time. This year has been rainy enough to keep them happy without any irrigation. Japanese maples do not like to have wet roots. They can easily get wilt and root rot diseases if planted in a wet spot.

I don’t think there’s anything you can do to help it at this point. If you stop irrigating it will likely shed some small limbs, stabilize, and regain health. You can remove larger limbs if you are convinced they are dead.

Losing limbs is not a bad thing for Japanese maples. They gain character that makes them unique.