The Effect of Reduced Doses of Trifluralin on Control of ‎Common Lamsquarters (Chenopodium album L.) and Redroot ‎Pigweed (Amaranthus retroflexus L.) in Potato (Solanum ‎tuberosum L.) Fields

To evaluate the reduced concentration effect of Trifluralin (Treflan EC 33%) on common lamsquarters (Chenopodium album L.) and redroot pigweed (Amaranthus retroflexus L.) in potato (cv. Agria) a field experiment based on randomized complete design with three replications was carried out at the Agriculture and Natural Resources Research Station of Ardabil during 2013. Treatments were concentration of Trifluralin (0.125, 0.25, 0.5, 1, 2 and 4 Lit a.i/ha) without weed control and weeding out (as control). Sampling of weeds were performed before and after flowering of potato. Statistical analysis showed significant differences of reduced concentrations of Trifluralin on reduction of both lamsquarters and pigweed in the field. The highest reduction in percentages of weed densities, before and after flowering (91.94 and 90.34 percent, respectively) were achieved by using 4 Lit a.i/ha of Trifluralin. Application 4 Lit a.i/ha of Trifluralin at before and after flowering reduced common lamsquarters density by 87.13 and 86.04 percentages, respectively. Application 4 Lit a.i/ ha Trifluralin at befor and after flowering reduced pigweed density by more than 90 percent. Experimental results also showed that different concentrations of Trifluralin had significant effect on mean tuber weight per plant, and potato tuber yield. The highest mean weight of tuber per plant, yield per plant and potato tuber yield was obtained at 2 Lit a.i/ha Trifluralin concentration, while it was not significantly different from that of 4 Lit a.i/ ha. Generally, application of 2 and 4 Lit a.i/ha Trifluralin incereased tuber yield by 51.85 and 50.74 percents respectively.