Q.Fungus On Wisteria Trunk, Mushroom Like Growths On Trunk
This is a white wisteria, 18 years old, excellent flowers each year. This year I noticed that the leaves had changed to a much paler green towards the end of the summer. Photo attached of the mushroom fungus. We had applied a mulch of bark in the general area to suppress weeds.
Certified GKH Gardening Expert
That looks to be from one of two genera. That is, either, Pleurotus (The common Oyster Mushroom is what I suspect) or Omphalotus (If it glows, then you can be sure that it is from this genus). Either way, it is not the cause of the plant's demise. It IS taking advantage of something likely brought about by your application of mulch.
An application of the fungicide of your choice, and a good feeding should take care of the issue. You can remove the fruiting bodies, but the rest of the mushroom is still inside of the plant, and in the ground around. The fungicide will take care of it, and any other microbes that ARE causing the demise of the plant.