Laboratory experiments were conducted to assess the influence of surfactants applied with or without nitrogen on MON 37500 foliar absorption by Bromus tectorum, Bromus japonicus, Aegilops cylindrica, Triticum aestivum, Chorispora tenella, and Lactuca serriola. MON 37500 absorption in B. tectorum and B. japonicus increased from 40% 24 h after treatment (HAT) to 48% 48 HAT, averaged across surfactants with no added nitrogen. Averaged across nitrogen source and species, nonionic surfactant, ethylated seed oil, and organosilicate provided comparable enhancement of MON 37500 absorption (56 to 68%), whereas crop oil concentrate provided only 27 to 29% absorption under the same conditions. Averaged across species and surfactant class, urea ammonium nitrate had the greatest effect on MON 37500 absorption (68%), compared to ammonium sulfate (59%) or no nitrogen (40%). Nitrogen, regardless of the type, significantly improved foliar absorption of MON 37500. MON 37500 absorption by species was 71, 63, 57, 57, 49, and 38% in C. tenella, B. japonicus, T. aestivum, A. cylindrica, B. tectorum, and L. serriola, respectively, when averaged across surfactants and nitrogen. Densely pubescent B. japonicus leaves did not retain significant amounts of MON 37500 following a primary leaf wash.

BAY MKH 6561, a sulfonylaminocarbonyl-triazolinone herbicide for postemergence control of annual grasses and selected broadleaf weeds in wheat, was evaluated for weed control and rotational crop (barley, pea, lentil, and mustard) injury in the Pacific Northwest. BAY MKH 6561 was applied postemergence in winter wheat at 22, 45, and 90 g ai/ha during fall 1997 and spring 1998 near Moscow, ID, Pendleton, OR, and Wilcox, WA, to determine its effect on barley, pea, lentil, and mustard planted during spring 1999. At Pendleton, BAY MKH 6561 reduced barley height 6% and grain yield 11%, when applied in the spring at 90 g/ha, and visibly injured mustard 4 to 19% when applied at 45 or 90 g/ha. All BAY MKH 6561 treatments reduced mustard seed yield 47 to 54% at Moscow and 38 to 48% at Wilcox. Pea and lentil seed yields were not affected by herbicide treatments at all locations, whereas barley was not affected at Moscow and Wilcox. In growth chamber soil bioassay experiments, fall-applied BAY MKH 6561 dissipated 10 to 48% faster at Moscow compared to Pendleton, and the predicted half-life ranged from about 68 (Moscow) to 79 d (Pendleton). Dissipation of spring-applied BAY MKH 6561 at 45 and 90 g/ha was 17 to 21% slower at Moscow than Wilcox, and the predicted half-life ranged from 60 (Wilcox) to 69 d (Moscow).