Imazapyr, a non-selective herbicide used for the control of a broad range of weeds including terrestrial annual and perennial grasses and broadleaved herbs, woody species, and riparian and emergent...
Q: Why is a helicopter called a "Chopper"?
A: I think the names comes from the sound of the blades make: whop-whop or chop-chop.
FYI, the helicopters that have the loud popping of the blades...