Investigating Combination of Herbicides in Canola for Better Control of Weeds, with Special Reference to Brassica Weeds

In an experiment in randomized complete blocks design with four replications and 17 treatments, combinations of trifluralin (Treflan 48% EC) with metazachlor + quinmerac (Butisan Star, 41.6% SC) were tried to achieve a better control of canola weeds, especially Brassica family in Khuzestan, Golestan, Mazandaran and Fars provinces. Treatments included Treflan at 2 L/ha. ppi + clopyralid (Lontrel, 30% SL) at 0.8 L/ha. post emergence of broadleaf weeds, Treflan at 1.5, 2 and 2.5 L/ha. ppi, Butisan Star at 1.5, 2 and 2.5 L/ha., preemergence, combinations of Treflan+Butisan Star at doseges used above, weed-free check. Haloxyfop-R-methyl ester (Galant Super 10.8% EC) at 0.75 L/ha was sprayed over the whole experiment to control grassy weeds. Results indicated that In Fars and Golestan, combinations of the two herbicides caused serious injury to canola and the weed control efficacy of herbicide combinations was not much better than Butisan Star alone. In Mazandaran results were similar, but canola did not show injury as a result of herbicide combinations. In Khuzestan, herbicide combinations not only did not damage canola but also had a better control of weeds and increased canola yield. Due to different types of soil in various regions, results varied, and therefore, it was recommended that before applying combination of above herbicides in any new place, they should be tested.