Studies On Sensitivity To Corn And Application Technology Of Quinclorac In Corn Field

In order to solve the question that there is lack of postemergence herbicide in corn field in China, the sensitivity of quinclorac to com and the joint action, the best dosages of two and three herbicides mixed quinclorac with bendazone and MCPA-Na was studied in this paper.The potted experiment was conducted to study the influence of soil moisture on control efficacy to barnyard grass and sensitivity to corn of quinclorac. When the soil moisture increased from 20% to 50%, it improved control efficacy of quinclorac to barnyard grass and reduced the safety to corn gradually, but the selection index increased from 1.66 to 2.22. It is obvious that the higher soil moisture, then the safer quinclorac was to corn on this condition of the same effect on barnyard grass.The sensitivity of quinclorac to corn in different growth stages was studied through potted experiment. The bigger corns, the more sensible quinclorac was to them. According to the inhibitory rate of fresh weight and the eye estimating toxicity, we thought the optimum period applied quinclorac in corn field was 1.5 leaves to 3.5 leaves of corn.A field experiment was carried out to evaluate the sensitivity of quinclorac in different corn cultivars. The sequence of sensitivity of quinclorac to offered corn cultivars was KN-Yihao > DN-Zaonian > DN-888 > DN-248 > DN-9701. The special corn cultivars were more sensible than common corn cultivars. Applied quinclorac when corn was during the period of 4.5 leaves to 5.5 leaves, the safe dosage of quinclorac was 900g a.i./hm2 in DN-9701 field and 600g a.i./hm2 in DN-248 and special corn cultivars field.Using methods of rotational regression design, a field experiment was conducted to evaluate joint action and the best dosages of two and three herbicide mixed quinclorac with bendazone and MCPA-Na. The results showed that there were synergism between quinclorac and bendazone, quinclorac and MCPA-Na, bendazone and MCPA-Na. After the models of corn yield were analyzed, it was concluded that the three best dosages of herbicides combination were quinclorac (903g a.i./hm2) + bendazone (918.15g a.5./hm2), quinclorac (938.9g a.i./hm2) + MCPA-Na (693.2g a.i./hm2), quinclorac (811.6g a.i./hm2) + bendazone (552.3g a.i./hm2) + MCPA-Na (552.3g a.JJhm2).In our studies, the feasibility that quinclorac could be applied in special corn field filled up the blank mat no herbicide could be used to control the grass in special corn field, conduced to apply herbicides in special com field and to increase planting acreage of special corn and to optimize corn planting structure in Heilongjiang Province. The best dosages of two and threeherbicides mixed quinclorac with bendazone and MCPA-Na played an importantly directive role in postemergence chemical weed control in com field, provided theoretical basis for postemergence chemical weeding and had practical application merit. They were of advantage to resolve the problem that there was lack of herbicides, and improved the level of chemical weeding in corn field in Heilongjiang Province and even in China.