Greenhouse studies were conducted to determine the responses of ripgut brome and foxtail brome to MON 37500 applied at rates up to 80 g/ha. At 30 d after treatment MON 37500 at 20 g/ha reduced fresh weight of ripgut brome by 89% when applied at the three-leaf stage and 57% when applied at the tillering stage. MON 37500 at 10 g/ha reduced fresh weight of foxtail brome by 80% when applied at the three-leaf stage and 61% when applied at the tillering stage. Rates above 20 g/ha did not increase control of either species. In field experiments during 1998 to 1999 and 1999 to 2000 in Settat, Morocco, bread wheat tolerated MON 37500 at 67 g/ha. Ripgut brome control in the field was 78% in the first growing season and 90% in the second season when MON 37500 was applied at 27 g/ha to brome plants at the one- to four-leaf stage. A similar rate controlled tillering ripgut brome by 69% during 1998 to 1999 and 62% during 1999 to 2000. MON 37500 at 20 to 30 and 10 to 20 g/ha applied before tillering controlled ripgut brome and foxtail brome, respectively, ≥ 70%.
Nomenclature: MON 37500,1-(2-ethylsulfonylimidazo[1,2-a]pyridin-3-ylsulfonyl)-3-(4,6-dimethoxypyrimidin-2-yl)urea; foxtail brome, Bromus rubens L. #3 BRORU; ripgut brome, Bromus rigidus Roth #BRORI; wheat, Triticum aestivum L. ‘Tilila’.
Additional index words: Herbicide, weed control efficacy, rainfed wheat.
Abbreviations: DAT, days after treatment; NIS, nonionic surfactant; POST, postemergence; PRE, preemergence.