Herbicides selection of alfalfa pasture in the central area of Jilin Province

The slow growth of alfalfa (Medicago sativa) at seedlings stage results in the rapid growth of weeds, which severely affects the quantity and quality of alfalfa products. Six common herbicides with low toxicity and suitable for legume were selected for further evaluation. The results showed that 90% acetochlor with 2.0 L·hm-2 spraying in the soil after sowing had best effects which reached 93.81% of relative weeds prevention rate and did not affect yield although alfalfa seedlings grew slowly. Different herbicides should be selected according to different weed species when spraying on alfalfa leaves. The application of 40% bentazone with 3.0 L·hm-2 had 97.09% of relative prevention rate of Echinochloa phyllopogon which also had no harms to alfalfa. The application of 15% fluazifop-p-butyl with 1.0 L·hm-2 effectively control Cirsium setosum and Metaplexis japonica which had 93.63% and 100% of relative prevention rate, respectively. Herbicide was not recommended for Chenopodium album, Portulaca oleracea, Abutilon theophrasti which should be prevented manually.