Black plastic to kill grass for guilds

I just put down black plastic around my fruit trees because grass had overtaken them last year as I did not keep up with weeding. I initially used newspaper and then wood chips to make the guilds around my fruit trees. They are out in the pasture with grass growing around them. Anyway, this time I laid down black plastic in a circle around the trees and kept the plastic one foot away from the trunks. Does anyone know if the black plastic will kill the roots of the trees? It gets hot here in Boise and is already in the 90sd.

Thanks, Beth

Not sure about the heat. My concern is water. Is the plastic clear of the drip line of the tree?