Both broadleaf and grassy weed species can negatively impact cotton growth, development, defoliation and quality. Studies are being conducted in the San Joaquin Valley of California to determine the effects of Staple (pyrithiobac sodium) with Fusilade (fluazifop), Poast (sethoxydim), and Prism (clethodim) when the grass herbicides are either tank mixed with or applied after the Staple application. At 21 days after application (DAT) in 1996, there was no indication of antagonism. At 28 DAT in 1997 there was no indication of antagonism with the Poast or Prism tank mixes or sequential treatments, however there was evidence of antagonism with Fusilade on barnyardgrass (Echinochloa crus-galli).