Halosulfuron: Crop Tolerance, Weed Control and Species Sensitivity in Dry Beans
Halosulfuron: Crop Tolerance, Weed Control and Species Sensitivity in Dry Beans Zhenyi Li Advisors: University of Guelph, 2016 Dr. Peter Sikkema and Dr. Rene Van Acker Twelve field experiments were conducted over a two year period (2013, 2014) to evaluate the tolerance of white bean to halosulfuron and spectrum of weeds controlled with halosulfuron applied alone and in combination with trifluralin, pendimethalin, EPTC, dimethenamid P or S metolachlor applied preplant incorporated (PPI) and pendimethalin, dimethenamid P or S metolachlor applied preemergence (PRE) At 1 and 4 weeks after emergence (WAE) halosulfuron applied PPI or PRE, applied alone or in combination with trifluralin, pendimethalin, EPTC, dimethenamid P or S metolachlor caused 3% At 4 and 8 WAE, halosulfuron applied PPI or PRE provided 90% control of common lambsquarters, wild mustard, redroot pigweed and common ragweed and 60% control of green foxtail. Weed biomass and density data reflected the weed control ratings. White bean yield with halosulfuron applied in combination with trifluralin, pendimethalin, EPTC, dimethenamid P or S metolachlor was equivalent to the weed free control. Halosulfuron absorption, translocation and metabolism were studied in white and adzuki bean. Halosulfuron was absorbed more rapidly in adzuki bean than white bean. Adzuki bean reached 90% absorption (t90) 26.2 hours after treatment (HAT) while white bean required 40.1 HAT to reach t90. The maximum halosulfuron absorption (Amax) was higher in adzuki bean (75.7% than in white bean (65.3% More C halosulfuron was translocated to the apex, 1 trifoliate, stem above the treated leaf and roots in aduzki bean than in white bean. The maxiumum radioactivity translocated out of treated leaf (Tmax) was higher in adzuki bean (17.7% than in white bean (12.1% Halosulfuron was broken down to the same metabolites in white and adzuki bean. The half life of halosulfuron in adzuki bean and white bean was 16 HAT and 6 HAT, respectively. Differential tolerance of white and adzuki bean to halosulfuron can be attributed to greater absorption, greater translocation and decreased metabolism in adzuki bean.