Japanese Blood Maple

Asked May 4, 2013, 11:43 AM EDT

I have a 20-foot Japanese Blood Maple in my yard bed. I discovered last year that one of the branches was leafless, except for close to the trunk. This Spring, I have several leafless branches. Do you have a regimen for determining if it is diseased or infected by an insect?

Marion County Oregon

3 Responses

Hi:

This sounds a lot like Verticillium Wilt, unfortunately. I've attached a link to the PNW Disease Management Handbook entry on this disease. Feel free to contact me for more information.

http://pnwhandbooks.org/plantdisease/maple-acer-sp-verticillium-wilt

Hi Neil, thank you for your help! I sprayed the tree and drip line with copper sulfate 50%. Larger affected branches have sparse leaf growth on tips and normal leaf growth nesr the trunk. Should I remove all affected branches at the the trunk or above the healthy leaf growth near the trunk? Or is the tree not likely to improve? Should I continue spraying with copper sulfate for a couple more applications within a month period?

HI:

If in fact it is Verticillium the copper will not help. Copper can protect the plant from foliar diseases but Verticillium affects the water-conducting tissues inside the plant. I would remove the branches above healthy growth I suppose and clean the snippers or saw between cuts thoroughly with a 10% bleach solution or 70% alcohol. Japanese Maple affected by Verticillium wilt tend to decline branch by branch over a number of years. Eventually they become so sparse that they lose most of their ornamental appeal. Like other vascular diseases, this one has no cure, I'm afraid.