verticillium wilt and ?
We have two large maples with verticillium wilt. What is the other disease I see (second photo)? Also, with several large sections of each tree affected by verticillium wilt, is it worth cutting out the branches - or should we remove the entire tree? I'm wondering if the shock of cutting out large trunks (each tree has two or three, and we need to remove at least one whole trunk from each) will weaken and kill the tree anyway. Thank you.
Multnomah County Oregon
Thank you for your questions about your maple tree. Have you had a laboratory test for this fungus? It certainly looks as if your tree is 'flagging'--groups of branches all dying off, but there are a few other causes of this, and verticillium wilt is probably the most serious of the group.
If your tree in fact has v.w., it is a soilborne fungus that cannot be cured, and it will continue to kill off your tree section by section. One of the things you can do is to remove the dead branches, but that's more of a safety issue than that it's helping the tree. Here is a link to a portion of an OSU handbook that describes it, with a few recommendations, one of which is removing the infected branches and leaves. Here is a link to another Extension article that has a list of susceptible trees and shrubs, resistant trees and shrubs, and an excellent discussion of how this operates in the tree.
I can't tell if the tree with the bark splitting is the same as the two that have v.w. Older trees get this due to extreme weather changes, and are rarely a long term concern. Trees heal themselves, and applying some sort of sealant is not recommended. (And, if this tree is one with v.w., the bark split is the least of your problems.)
Hope this is helpful. Good luck!