verticilium wilt or phytophthora?

Asked June 7, 2017, 10:39 AM EDT

HELP! I have a large big leaf maple in my yard that is half dead and the rest is dying. One arborist told me it was phytophthora and another that it is verticilium wilt. We are putting in a replacement tree and want to be sure that the new tree will not be effected. Any suggestions on tree types or how to make proper diagnosis? Any labs or tests you would suggest? Thank you Eugene Gilden

Yamhill County Oregon maple tree

1 Response

Thank you for your question about your maple tree. Sorry.... So, although both verticillium wilt and phytophthora are soil-borne fungi, verticillium wilt is distinctive in how it impacts the plants. That is, it 'takes out' one branch or section of the tree at a time, called 'flagging.' You can see this phenomenon in the pictures in the link. Phytophthora, on the other hand, is a fungus that requires flooded or poorly drained soil.

Verticillium wilt can remain in the ground for 5 or more years, and any tree susceptible to it will become infected. This link has a list of plants resistant to it, as well as a list of susceptible plants. Verticillium wilt can be diagnosed by cutting longitudinally a branch that has flagged, so that you can see if there are brown 'streaks' where clear 'veins' should be.

Phytophthora symptoms show up on leaves, but are more 'splotchy', and there are often lesions on the trunk and/or stems. As its 'common name,' "Sudden Oak Death" implies, it can destroy a tree in a very short period of time. Here is a link to an article with photos of damage. Phytophthora. too, will impact many woody plants, but curing the water issue is essential.

You can, if you like, submit a sample of the tree to the OSU Plant Clinic in Corvallis through this link. I suggest you not plant another tree before you have a laboratory diagnosis of the fungus. Good luck!