Efficacy of different herbicides in controlling of alfalfa (Medicago sativa) weeds in Shahr-e-kord

Broadleaf weeds cause serious damages in the new established alfalfa fields.In order to evaluate the efficacy of some herbicides in controlling broadleaf weeds in newly planted alfalfa fields,an experiment was conducted in a randomized complete block design with 8 treatments and 4 replications in Chahar takhteh station of Research and Education Center of Agriculture and Natural Resources Chaharmahal and Bakhtiari Province (Shahr-e-kord) during the summer of 2013-2014. Treatments were Eptam (Eradicane EC 82%) dose 5 Lha-1, Metribuzin (Sencor WP 70%) dose 750 gha-1, 2,4-DB (Butress EC 42.3%) doses 3 and 3.5 Lha-1, Bentazon (Bazagran SL 48%) dose 3 Lha-1, Imazethapyr (Pursuit SL 10%) doses 0.5 and 1 Lha-1 (with 200 ml citogit), and control (weed infested).The results showed that the highest efficiency was observed in 1 L Imazethapyr ha-1 that on average, in all three harvesting, the density and biomass of shepherd needle, nettle and bogloss was decreased 83 to 89.5% and 82.5.to 97.6%, respectively. Also 1 L imazethapyr ha-1 resulted the highest alfalfa biomass in the first and third harvesting of  (53.9 to 87.1%),and in the second harvesting, 3.5 L 2,4-DB (Butress EC 42.3%) ha-1 resulted in the highest alfalfa biomass (90.4%). Overall, imazethapyr controlled weeds well and it was a suitable herbicide for alfalfa fields due to low dose and reduction of adverse environmental effects.