Control of Annual Bluegrass (Poa annua) in Perennial Ryegrass (Lolium perenne) Seed Fields

Ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] applied postemergence in November at rates from 1.4 to 4.5 kg/ha eliminated all annual bluegrass (Poa annuaL.) that had survived application of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] in fall carbon-planted perennial ryegrass (Lolium perenneL.) seed fields. Ethofumesate also eliminated all annual bluegrass in established perennial ryegrass seed fields when applied in late October at rates from 1.1 to 3.4 kg/ha or when applied as sequential treatments with atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] at 1.4 kg/ha or with simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] at 2.2 kg/ha. In most experiments, perennial ryegrass seed yields were not adversely affected by applications of ethofumesate alone or by sequential treatments with diuron, atrazine, or simazine.