Evaluation of forage yield and weed control of alfalfa (Medicago sativa L) under the influence of different herbicides

In order to efficiency of different herbicides on weed control, forage yield, crop growth rate (CGR) of alfalfa (Medicago sativa L), an experiment with nine treatments based on randomized complete block design (RCBD) with three replications at the research field of Iranian Research Institute of Plant Protection located in Meshkindasht, Karaj, during 2014-2016 was conducted. The treatments consisted of Eradicane 4.1 g ai/ha (EPTC), Metribuzin 525 g ai/ha, 2,4-DB 1269 g ai/ha, 2,4-DB 1480 g ai/ha, Bentazon 144 g ai/ha, Imazethapyr 50 g ai/ha (with 200 ml Sitogit), Imazethapyr 100 g ai/ha (with 200 ml Sitogit), non-herbicide control (weedy) and whole-season weeding control (weed free). Among different herbicides, application of Imazethapyr (1L/ha) led to control of Flixweed (Descurania Sophia) and wild mustard (Sinapis arvensis) (control percentage more than 95%). The lowest percentage of dry weight reduction in both weeds (flixweed and wild mustard) was related to Eradicane herbicide, which was 42 and 41% in the first cutting and 40 and 35% in second cutting. The highest and lowest fresh and dry weight of alfalfa (qualitative forage yield in 5 cutting were observed weed free and application of Metribuzin herbicide treatments. Also, index of crop growth rate (CGR) was more in weed free and application of Imazethapyr herbicide (1L/ha) treatments. Therefore, weed control in alfalfa established, application of Imazethapyr herbicide (1L/ha) as post emergence (3-4 leaves of weeds) is recommended.