Development Of Formulation Of 23% Waterable Powder Combined Bensulfuron-methyl And Its Controlling Efficiency Against Weeds In Rice Field

Metolachlor have high effect in controlling weeds of grass family, bensulfuron-methyl can control most broadleaf weeds and some Cyperaceae. in order to control weeds in rice fields, the author had mixed metolachlor with bensulfuron-methyl according to some rules and got a new herbicide, 23% mixture of metolachlor and bensulfuron-methyl WP. This chemical consist with metolachlor and bensulfuron-methyl at the ratio of 20: 3.The data of laboratory toxicity trails showed the mixture of metolachlor and bensulfuron-methyl have addition effect on Echinochloa crusgalli(L) Beauv.. Monochoriavaginalis(Burm.f.) presl ex kunth. The mixture is safe to rice and should be applied before the one leave stage of Echinochloa crusgalli(L) Beauv., after usage the rice field should keep water layer 3 to 4 cm by 5 to 7 days. The proper ratio range of the mixture of metolachlor and bensulfuron-methyl should be 4.5:1 to 9.0:1, according to control effect and cost the most proper ration is 20:3.The toxicity experiment of 23% mixture of metolachlor and bensulfuron-methyl WP showed this chemical is low toxicity pesticide, acute toxicity of LD₅0 per os and epiderma to male and female rice are all above 5000mg per kilogram, but it has lightly stimulation to eyes.The analysis standard of this mixture had established by HPLC. This standard had approved by Bureau of Hunan Quality and Technology Inspection.The mixture of 23% metolachlor and bensulfuron-methyl WP has lager scale field trials in Hunan province and Jiangsu province during 2004 and 2005. The experiment showed the mixture of metolachlor and bensulfuron-methyl WP had got satisfactory effects in controlling Echinochloa crusgalli(L) Beauv., MonochoriavaginalisfBurm.f.) presl ex kunth, Sagittariapygmaea Miq. Rotala indica(willd) koehne. Linderniaprocumbens (krock)philcox, Cyperus difformis L, Cyperusiria L and so on. The proper time of the mixture application should be before one leave stage of Echinochloa crusgalli(L) Beauv. and after rice transplanting 5 to 6days, it should be mixed with soil together at the dosage 30gram per 667m2, there should have a 4 to 5 cm depth water layer in rice field before the chemical application and the water layer should keep 5 to 7 days after its application, the index of effect on weeds can keep above 90% and can last 50 days. The mixture is safe to rice at the dosage below 40 grams per 667m2, and has remarkable effect on increasing productions.This mixture had been applied for extension in Hunan, Jiangsu and Hubei province and had got remarkable economical benefits.