Published online by Cambridge University Press: 12 June 2017
The influence of hot-dry and cool-moist environments on primisulfuron efficacy on giant foxtail and quackgrass was compared at the University of Wisconsin Biotron. Primisulfuron was applied POST at 20 and 40 g ai ha-1 with nonionic surfactant (NIS) or crop oil concentrate (COC) and with or without 28% nitrogen fertilizer (28% N). Giant foxtail control 3 wk after treatment was not affected by primisulfuron rates or adjuvants. Adding 28% N tended to improve quackgrass control with primisulfuron plus NIS or COC. Primisulfuron was more injurious to both giant foxtail and quackgrass in the cool-moist than the hot-dry environment. Absorption of 14C-primisulfuron into giant foxtail tissue 3 days after treatment (DAT) was greater in the cool-moist than the hot-dry environment Translocation of 14C out of treated leaf of quackgrass 3 DAT was greater in the cool-moist than the hot-dry environment. More 14C was absorbed and translocated in giant foxtail than quackgrass. Absorbed 14C was translocated equally to underground and above treated leaf sections of quackgrass, whereas more 14C was translocated above the treated leaf of giant foxtail.