Tree canker

Asked August 17, 2020, 11:24 AM EDT

Hi, I live on 1.79 acres in the Willamette Valley with a variety of trees including Douglas fir, black walnut, white oak, ponderosa pine, and maple. All of my oak trees except one are afflicted with an oozing canker and now one of my large maple trees is infected with it too. I need help identifying the problem and figuring out how to eradicate it. So far, only the oaks and one maple have this problem; all of my other trees are fine (including my giant black walnut tree, which has been here longer than any of the others). Thanks. --MATT

Washington County Oregon

1 Response

Hello, wow, that is a tough problem for me to diagnose even with a nice picture like that. One possibility is the carpenter worm, which attacks hardwoods, including oak and maple. I think it would take an arborist to actually visit the trees to confirm this. Here is a fact sheet on carpenterworm, a moth caterpillar:

Here is a book about oak issues and on page 60 is a write up on carpenter worm.

I hope this is helpful, but you may need to get an expert to diagnose this. If you chip away the bark lightly around the source of the ooze, you may notice a distinct hole going into the wood, that may indicate the carpenterwom.