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

Abstract

Laboratory experiments were conducted to assess the influence of surfactants applied with or without nitrogen on MON 37500 foliar absorption byBromus tectorum, Bromus japonicus, Aegilops cylindrica, Triticum aestivum, Chorispora tenella, andLactuca serriola.MON 37500 absorption inB. tectorumandB. japonicusincreased 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% inC. tenella, B. japonicus, T. aestivum, A. cylindrica, B. tectorum, andL. serriola, respectively, when averaged across surfactants and nitrogen. Densely pubescentB. japonicusleaves did not retain significant amounts of MON 37500 following a primary leaf wash.