Fungus on Chinese Wisteria
On the stem about 1 to 2 feet above the root, there is an ugly type of fungus growing on wisteria tree. What to do about it?
Certified GKH Gardening Expert
If it is a toadstool type growth, you can remove it and treat the area with a fungicide. But, truth be told, they are not harmful to the plant so you can also just leave it.
If it is a gall, which is more like a growth out of the plant than a separate organism, there are many things that can cause it. Most of the time, they are not harmful to the plant, but with a plant like wisteria, it could girdle it and kill it. Wisteria are susceptible to crown galls, so this article may be helpful if you feel it is a crown gall: http://www.ipm.ucdavis.edu/PMG/r280101311.html