In a recent presentation to the U.S. Environmental Protection Agency, WSSA representitives reported that nine weed species in the United States now have confirmed resistance to glyphosate. Among these weeds are strains of common ragweed (Ambrosia artemisiifolia), common waterhemp (Amaranthus rudis), giant ragweed (Ambrosia trifida), hairy fleabane (Conyza bonariensis), horseweed (Conyza canadensis), Italian ryegrass (Lolium multiflorum), johnsongrass (Sorghum halepense), Palmer amaranth (Amaranthus palmeri) and rigid ryegrass (Lolium rigidum).
9 vrsta korova, kod amera, postalo otporno na glifosat. između osalog 2 vrste ambrozije.