Trunk of my wisteria tree is wrinkled
I have been fussing with a wisteria tree for a time now.
I have been trying to bonsai it. I got it as a sapling and it was a bare tree with new buds. I potted it in a cascade style bonsai pot and it took off.
The buds grew into many leafy branches. Over a period of time I began to notice that the leaves were wilting/drooping.
I knew I was not over watering the plant so I figured it had to be the soil. I purchased some well draining bonsai soil and repotted it, but to no avail.
It is still wilting and drooping and now the trunk appears wrinkled at the base. I remember reading about this somewhere as a prelude to some condition but I can't remember what.
What is wrong with my plant?
Oh, boy, that doesn't sound good. Unfortunately, making any kind of tree or vine in to a bonsai can be a very stressful process for any plant, and in these situations they can be susceptible to many pests and diseases that they otherwise could just shrug off.
It's possible that your Wisteria has verticillium wilt or some other pathogen, which would explain the wilting of the foliage, and the wrinkling bark on the stem. Sadly, this usually spells the end to the plant. Verticillium wilt is all around us in the form of spores, so it's impossible to protect the plant from something like this; all it takes is a wound while pruning to introduce it, and it's game over.
Depending on if your Wisteria is grafted, one thing that is a last ditch effort to try is to cut it right back to the soil. Sometimes the roots stay alive, and then the plant can make new growth from below the damage. Keep in mind that if the plant is grafted, the root stock won't be the same kind of wisteria, but something very vigorous.
The only course of action that I can suggest now is no action at all; put the plant where it will get bright light, but no full sun, water very carefully and wait and see. Sometimes, putting a plant on 'ignore' can give it the best chance of recovery.
I very much hope you can revive the plant, it will be spectacular to see a tiny version of Wisteria, blooming.
Best of luck,