草铵膦对桑园杂草的防除效果和对家蚕的毒性试验

Control Efficacy of Glufosinate on Weeds in Mulberry Field and Testing of Its Toxicity to Silkworm

以草铵膦、百草枯和草甘膦3种灭生性除草剂进行桑园杂草防除试验,以及对家蚕的毒性试验,评价新一代除草剂草铵膦的药效和安全性。200 g/L草铵膦AS 150倍、100倍和75倍稀释药液对桑园杂草的田间防除效果与30%草甘膦AS150倍稀释药液相近(P>0.05),均优于200 g/L百草枯AS 100倍稀释药液(P<0.01),除草的速效性明显优于30%草甘膦AS150倍稀释药液,持效期在30 d以上,比200 g/L百草枯AS 100倍稀释药液明显延长。200 g/L草铵膦AS对家蚕3龄起蚕的24 h急性经口毒性(LC50)为421.366 2 mg/L,其毒性高于30%草甘膦AS(LC50>6 000 mg/L),低于200 g/L百草枯AS(LC50=194.828 2 mg/L)。用200 g/L草铵膦AS 150倍、100倍和75倍稀释药液直接喷洒桑叶后3 d左右采叶养蚕,家蚕仍表现出明显的药害症状;喷药后4~5 d桑树叶片枯黄,在桑叶上的残毒期>5 d。建议在桑园使用200 g/L草铵膦AS 150倍稀释药液,应定向对杂草茎叶部位均匀喷雾,避免喷洒到桑树枝干和叶片,喷药后5 d内勿采叶养蚕。

The control efficacy and security of novel herbicide glufosinate was evaluated by comparing the control effi- cacy on weeds in mulberry field and its toxicity to silkworm （ Bombyx mori） with two other sterilant herbicides, paraquat and glyphosate. The field control efficacy of 150 times, 100 times and 75 times dilution of 200 g/L glufosinate aqueous solution （AS） were close to that of 150 times dilution of 30% glyphosate AS and were superior to that of 100 times dilu- tion of 200 g/L paraquat AS （ P〈0.01 ）, and the quick acting weeding effect of glufosinate diluted solutions was much better than that of 150 times dilution of 30% glyphosate AS. The efficacy period of glufosinate diluted solutions lasted more than 30 days, which was longer than that of 100 times dilution of 200 g/L paraquat AS. Acute oral toxicity （LCso） of 200 g/L glufosinate AS to the 3rd instar newly exuviated silkworm larvae at 24 h was 421. 366 2 mg/L, which was higher than that of 30% glyphosate AS （ LCso 〉6 000 mg/L）, but lower than that of 200 g/L paraquat AS （ LCso = 194. 828 2 mg/L）. Apparent toxicity symptoms of silkworm larvae still occurred after being fed with mulberry leaves harvested at day 3 after directly spraying with 150 times, 100 times and 75 times dilution of 200 g/L glufosinate AS. And yellow mulberry leaves appeared at day 4 to day 5 after spraying, showing that its residual toxicity period lasted more than 5 days in mulberry leaves. It is recommended to directly spray 150 times dilution of 200 g/L glufosinate AS onto stem and leaves of weeds evenly in mulberry field, avoid spraying herbicides onto mulberry branches and leaves,and not to harvest mulberry leaves to feed silkworm larvae within 5 days after spraying.