Q: Wisteria has covered several trees in my yard. Is there a way to get it under control?
A: Wisteria is tough to control by any means. Earth moving machines can do the job quickly but you might lose your trees. Alternatively, if you have the time to devote, you can starve the roots by constantly killing the foliage above ground. This technique may take two years to get acceptable control. First, sever all major vines from their roots at ground level. Spray glyphosate (Roundup, etc) onto the stumps immediately. The chemical will be sucked back into the root system for a small distance but I’m positive it won’t kill the entire root mass.
If you have nearby too many small shoots to chop them all, spray them with glyphosate (Roundup, etc) or triclopyr (Brush-b-Gon, etc) herbicides. Canvas the area two months later and remove or spray any greenery you find. You’ll probably have new wisteria sprouts next spring and summer that you’ll have to hit once again.