Community Structure Characteristics Of Maize-Soybean Rotation Field And The Screening Of Herbicide Formula In Soybean Field

This study investigated the hazards of farmland weeds in the “grain-bean” rotation field model in the three northeastern provinces.Eight kinds of main crops and 31 kinds of commonly herbicides in the northeast region were selected,and herbicides excellent in the safety of various crops and the control of weeds were selected through relevant tests.Ten kinds of common weeds in soybean fields and several herbicides with excellent weed control efficacy were selected for compounding,and a formula with the best control effect and green safety was selected for the purpose of field use.The results are as follows:1.The random sampling method was used to investigate the species and distribution of weeds in soybean-maize rotation fields in seven cities in the three northeastern provinces.The results showed that 25% of grassy weeds and 62.5% of broad-leaved weeds were found in soybean fields in Liaoning Province.The dominant weeds were Echinochloa crusgalli,Xanthium sibiricum,Abutilon theophrasti and Commelina communis in soybean fields.25% of grassy weeds and 75% of broad-leaved weeds were found in corn fields.The dominant weeds were Eriochloa villosa and Abutilon theophrasti.25% of grassy weeds and 66.66% of broadleaf weeds were found in soybean fields in Heilongjiang Province.The dominant weeds were Echinochloa crusgalli,Abutilon theophrasti and Solanum nigrum;23.8% of grassy weeds and69.23% of broad-leaved weeds were found in corn fields.The dominant weeds were Echinochloa crusgalli,Calystegia hederacea Chenopodium album,and Chenopodium album.30% of grassy weeds and 60% of broadleaf weeds were found in soybean fields in Jilin Province.The dominant weeds were Eriochloa villosa;28.57% of grassy weeds and57.14% of broad-leaved weeds were found in corn fields.The dominant weeds were Echinochloa crusgalli and Eriochloa villosa.Through crops on herbicide sensitivity test results2.The efficacy of 31 herbicides and their selectivity to 8 crops were studied.The results show that pre-emergence herbicides of s-metolachlor,acetochlor,metolachlor and atrazinehad had excellent control effects on grass weeds;the postemergence herbicides of clethodim,azinidine,prapirazine,high-efficiency herb and quizalofop had good control effects on grass weeds;Pre-emergence herbicides of prometryn,2,4 D-butyl ester,oxamoxime,flufenoxan,propynfloxacin,and the postemergence herbicides of halosulfuron-methyl,mesotrione,nicosulfuron,iso-octyl fluopyronate,eucalyptus,dimethyl tetrachloro-sodium had good control effects on broad-leaved weeds.Different crops have different sensitivities to different herbicides.When herbicides were selected,weeds should be targeted for crops and weeds within the field.When using herbicides,it is necessary not only to consider the effects of control,but also to consider whether or not crops will cause injury.Considering the comprehensive economic and ecological benefits,it is recommended that conventional herbicides be used in actual production.3.Through the herbicide formulation optimization test,it was concluded that the best pre-emergence herbicide formulation was S-metolachlor3000ml·hm^-2 add propynfluorofurazone131.25g·hm^-2 and add flumetsulam300g·hm^-2;The postemergence herbicides was high-efficiency herb2250ml·hm^-2 add canopy 3750ml·hm^-2.In the actual production,the main weed communities in the farmland can be used for prevention and treatment.The above two formulas have special effects on common and difficult weed control in soybean fields and it is recommended that they be applied to actual production.