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?
Fungus on Chinese Wisteria
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