Control of Italian Ryegrass (Lolium multiflorum) in Wheat (Triticum aestivum) with Postemergence Herbicides1

Abstract

Field experiments were conducted in Virginia in 2000 and 2001 to determine the response of wheat and Italian ryegrass biotypes to postemergence applications of diclofop-methyl compared with several experimental and registered herbicides. Control of diclofop-methyl–sensitive Italian ryegrass by AE F130060 03 was similar to control by diclofop-methyl and was greater than that by chlorsulfuron plus metsulfuron, chlorsulfuron plus metribuzin, MON 37560, ICIA 0604, and CGA 184927. AE F130060 03 also controlled diclofop-methyl–resistant Italian ryegrass better than the other herbicides. Late-season spike density of diclofop-methyl–resistant Italian ryegrass was reduced 91 to 98% by AE F130060 03. Despite injury ranging from 10 to 24%, grain yield from wheat treated with AE F130060 03 was similar to or greater than yield from wheat treated with the other herbicides. Italian ryegrass control, spike density, and grain yield were not influenced by AE F130060 03 rate or addition of methylated seed oil.Nomenclature: AE F130060 03 {8.3:1.7 mixture of AE F130060 00, proposed common name mesosulfuron-methyl, 2-[(4,6-dimethoxypyrimidin-2-yl carbamoyl)sulfamoyl]-4-methanesulfonamido-p-toluic acid, plus AE F115008 00, proposed common name iodosulfuron-methyl-sodium, 4-iodo-2-[3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)ureidosulfonyl]benzoic acid}; CGA 184927, proposed common name clodinafop-propargyl, (R)-2-[4-[(5-chloro-3-fluoro-2-pyridinyl)oxy]phenoxy]propanoic acid 5-chloro-8-quinolinoxyacetic acid-1-methylester; chlorsulfuron; diclofop-methyl; ICIA 0604, proposed common name tralkoxydim, 2-[1-(ethoxyamino)propyl]-3-hydroxy-5-(2,4,6-trimethylphenyl)-2-cyclohexen-1-one; metribuzin; metsulfuron; MON 37560, proposed common name sulfosulfuron, 1-(4,6-dimethoxypyrimidin-2-yl)-3-[(ethanesulfonyl-imidazo[1,2-a]-pyridine-3-yl)sulfonyl]urea; Italian ryegrass, Lolium multiflorum Lam. #3 LOLMU; winter wheat, Triticum aestivum L. ‘Pioneer 2643’, ‘Pioneer 26R24’, ‘Pocohontas’.Additional index words: Diclofop-methyl resistance, resistance management.Abbreviations: ACCase, acetyl coenzyme A carboxylase (EC 6.4.1.2); ALS, acetolactate synthase (EC 4.1.3.18); MSO, methylated seed oil; POST, postemergence; PRE, preemergence; WAT, weeks after treatment; WBT, weeks before treatment.