The influence of surfactant and nitrogen on foliar absorption of MON 37500

Laboratory experiments were conducted to assess the influence of surfactant s applied with or without nitrogen on MON 37500 foliar absorption by Bromus tectorum, Bromus japonicus, Aegilops cylindrica, Triticum aestivum, Choris pora 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, a veraged across surfactants with no added nitrogen. Averaged across nitrogen source and species, nonionic surfactant, ethylated seed oil, and organosil icate provided comparable enhancement of MON 37500 absorption (56 to 68%), whereas crop oil concentrate provided only 27 to 29% absorption under the s ame 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 t ype, significantly improved foliar absorption of MON 37500. MON 37500 absor ption by species was 71, 63, 57, 57, 49, and 38% in C. tenella, B. japonicu s, T. aestivum, A. cylindrica, B. tectorum, and L. serriola, respectively, when averaged across surfactants and nitrogen. Densely pubescent B. japonic us leaves did not: retain significant amounts of MON 37500 following a prim ary leaf wash.