I have a friend who got some Velpar to remove invasive bamboo in his backyard. He didn't read the directions (of course) and applied it 2 or 3 times because it wasn't working. THEN he read the directions which said it was water activated. When it finally rained, it took out the bamboo, part of the neighbors yard and a neighbors tree. That ground was stile for about a year.
stile = sterile