Study On The Application Of Flumioxazin Controlling Weeds In Cotton Field

Cotton is the one of the most important economic crops and the plantation area is extensive in our country.The pre-emergence herbicides in cotton fields are mainly controlled gramineous weeds,and it is urgent to explore PRE-herbicides for control of the broad-leaved weeds in the cotton fields.Flumioxazin,with low toxicity,high efficiency and environmental friendliness,targets the protoporphyrin oxidase and belongs to N-phenylphthalimide herbicide in chemical class.In order to investigate the application prospect of flumioxazin in China,the weeds control spectrum,herbicidal activity and safety to various cotton varieties of flumioxazin were determined and the joint effect of flumioxazin and pendimethalin was evaluated in greenhouse or field experiments.The results are summarized as follows:1.Weed control spectrum was determined by the pot-culture method in greenhouse.The results indicated that flumioxazin had a wonderful herbicidal activity on common broad-leaf weeds and some gramineous weeds in cotton field,At the rate of 15 g a.i./hm~2,flumioxazin application resulted in higher than 90%fresh weight reduction of Portulaca oleracea,Amaranthus retroflexus,Chenopodium album,Chenopodium serotinum and Eclipta prostrate,and 80%-90%fresh weight reduction of Rorippa indica,Sonchus arvensis,Conyza canadensis,Solanumnigrum,DigitariasanguinalisandEleusineindica.Pendimethalin(185.6g/hm~2)had higher control efficacy on common grassy weeds in cotton fields such as Digitaria sanguinalis,Eleusine indica,Setaria viridis,Echinochloa crusgalli and Leptochloa chinensis,but had universal validity against on most broadleaf weeds.Therefore,flumioxazin and pendimethalin have complementary control spectrum,and the spectrum can be extended when used in mixture.2.The selectivity indexes between Lumianyan 28,Lumianyan 37,Xinqiu 4 and P.oleracea,A.retroflexus,S nigrum and C.album indicated that flumioxazin is much higher than that of pendimethalin,and the selectivity indexes of two herbicides are similar respectively to the diffirent cotton varieties.3.The research of safety to various cotton varieties by pot-culture in greenhouse method showed:At the rate of 150 g a.i./hm~2,flumioxazin application resulted in 4.9%~11.6%fresh weight reduction,and Shannongmian 7 and Chuangzamian 28 had higher inhibition rates,and the fresh weight reduction was 11.6%and 10.0%,respectively;herbicide resulted in2.2%~9.3%height reduction of the different cotton varieties,and Chuangzamian 28 were the most inhibited,with 9.3%height reduction.Flumioxazin is relatively safe herbicide to different cotton varieties.4.When flumioxazin was mixed with pendimethalin,the joint effect type was either additive or synergistic.The selective indexes of the two jointed herbicides against between Lumianyan 28 and P.oleracea,A.retroflexus,E.crusgall,D.sanguinalis were 28.55,26.81,24.88 and 19.27 respectively;the jointed herbicide against between Lumianyan 37 and P.oleracea,A.retroflexus,E.crusgall,D.sanguinalis were 35.28,33.35,30.96 and 23.98respectively;the jointed herbicide against between Xinqiu 4 and P.oleracea,A.retroflexus,E.crusgall,D.sanguinalis were 27.49,26.00,24.13 and 18.69 respectively,and it showed that the two jointed herbicides of flumioxazin and pendimethalin are safe to trial cotton,which make possible use of the herbicide in the cotton field.5.The field research showed that the jointed herbicides of flumioxazin and pendimethalin could extend the spectrum of weed control effectively and had better control efficacy for the broad-leaf and gramineous weeds.The control efficiency of jointed herbicides of flumioxazin and pendimethalin at the rate of 50.0g/hm~2+495.0g/hm~2,40.0 g/hm~2+594.0 g/hm~2,30.0g/hm~2+693.0 g/hm~2 were better than single dosage,and at the 40d after the pesticide application,the fresh weight reduction were 93.1%,92.0%and 91.8%,respectively,the height reduction were 93.8%,92.9%and 92.2%,respectively,and were safe to the cotton.In short,flumioxazin had an excellent efficacy on the common broad-leaved weeds and some grass weeds in cotton field;and it had a good safety to cotton crops,which indicated a good application prospect in our country.