killing grass around trees
I use only "direct contact" stuff like Round-Up for around trees and plants, but not the more powerful "total kill" systemic stuff like Pramitrol.
I use Pramitrol for my oyster shell & bark/pinestraw driveway, for instance, and Round-Up only around trees and plants, being very careful not to let the Round-up get on the tree or plant.
Round-Up will kill the plant that you put it on, and Pramitrol keeps working on roots, seeds, etc. and lasts much longer, usually for the whole season.