Sugar Maple (Acer saccharum) losing leaves Spring

Asked April 23, 2020, 8:36 AM EDT

Dear Expert,

I just notice part of my maple tree is losing its leaves now. Not sure if the cause is the water> Our loan was dried and we watered deeply for a couple of days not sure if it was the case. The new leaves are dropping and a it seems there is a bit of powder. This is a mature tree and we plant a loan couple of years not sure if this also affect the tree. We would appreciate your help. We love our tree!!

Contra Costa County California

1 Response

I can't tell for sure from your description and photos, but I suspect it may be a disease that is very common to maples--verticillium wilt. One of the characteristics is loss of leaves and death of branches on just a part of the tree. This can progress until most of the limbs are denuded. Verticillium is a fungal disease that lives in the soil and attacks the tree's vascular system. I'll give you more information about it, but I would suggest that you talk to the folks at the Contra Costa Extension office. They may be able look at a sample from your tree and give you better answers. Here's how to contact them:
One more thing--if you decide to take the tree out at some time in the future, be sure to replace it with a shrub or tree that is resistant to verticillium wilt--remember, the pathogen lives in the soil and can infect other susceptible plants.
There is usually a characteristic staining in the affected branches. Take a look at this image. Normal branch appearance is on the left. The brown staining on the right is what you might--not always--see with branches affected by verticillium wilt.
Here is a very good article from PNW Handbooks, with good images. Your care of the tree is going to be managing the problem, not curing it.
Check out the article:

  • Prune off and burn affected limbs preferably before leaves fall and thus before new inoculum is incorporated into the ground.
  • Clean pruning equipment after use.
  • Do not track soil from infested areas into clean areas. Clean boots, equipment, and tools before leaving an infested area.
  • Keep nitrogenous fertilizers to a minimum-enough only to produce normal, not succulent, growth.
  • If the tree dies and/or is removed, replace it with a nonsusceptible host such as any conifer, birch, dogwood, or sycamore.
  • Avoid planting maple in fields with a history of Verticillium wilt. Avoid fields previously planted to potato or tomato; however, former peppermint fields may be lower risk.
  • A preplant soil test for Verticillium propagules will help determine a planting site.
  • Incorporating freshly mown Italian ryegrass followed by covering the soil with plastic for 3 months in the late summer was effective in the Netherlands at reducing disease incidence in a nursery crop of Norway maple planted 6 months later. Effect was observed up to 4 years after planting.