Study On Development And Control Technique Of Spring Wheatfield Weeds In Qinghai

The weed specie, weed community structure and occurrence regulation in springwheat fields in Qinghai province were investigated in this research. The main weed speciesand occurrence period in spring wheat fields in Qinghai were preliminarily explored. At thesame time, the efficacy trials of different herbicides to different weeds and demonstrationof home-made combining herbicide Maikuojing was also tested, The research results wereas follows:1、There are87species,25families of weeds in spring wheat fields in Qinghai.monocotyledon are8species,1family. dicotyledon are79species,24families. Galiumaparine(L)Var tenerum Rcbb, Chenopodium album L., Radix PteroxygoniGiraldii,Elsholtiza densa Benth, Hypecoum leptocarpum Hook.f.et Thoms. and Polygonumaviculare L. are advantage weeds in wheat fields. Polygonum nepalense Meisn., Polygonumsibiricum Laxm., Avena fatua L., Phragmites australis, Stellaria media (Linn.)Cyr., Sonchusbrachyotus DC., Cephalanoplos setosum(willd)Kitam. are regional advantage weeds.2、In irrigation region of Qinghai, the emergence time of weeds in spring wheat fields isfrom mid April to mid-to-late June, duration is about50days, peak time of emergence isduring mid-to-late May; in Qinghai mountain regions, emergence time of weeds in springwheat fields is from late April to early to middle June, duration is about40days, peak timeof emergence is in early to middle May. The optimum depth of weeds emergence is1~2cm,the deepest depth is5.0cm and the shallowest depth is0.3cm, and the optimal depth ofweeds emergence is1~2cm soil layer.3、Weed population structure has significantly changed in spring wheat field in Qinghai.The farmland weed community structure has changed from wild oats and annualdicotyledonous weeds to perennial weeds and some resistant-herbcide annual weeds. hazardratio of Sensitive weeds Elsboltzia densa Benth, Avena fatua L., Daucus carota Linn.,Thlsaspiarvense, Lepyrodiclis holostecides were59.8%、48.1%、19.9%、29.4%、21.4%respectively,which decreased by30.3%、19.1%、35.3%、22.9%、24.6%; hazard ratio of resistant-herbcideweeds Galium aparine(L)Var tenerum Rcbb, Chenopodium album L., Sonchus brachyotus DC, Cephalanoplos setosum(willd)Kitam,Polygonum sibiricum Laxm., Polygonum aviculayeL.,Hypecoum leptocarpum HOQR were respectively56.3%、37.8%、81.2%、28.3%、17.7%、 51.9%、51.1%,which increased by19.9%、12.1%、14.3%、3.1%、3.0%、2.9%、0.4%。4、Four safe and effective herbicides were screened, they are50%pinoxaden,40%toluene oxadiazon WG.75%oxime grass Ketone�'bromoxynil WG and24%azole grass�'Benzene metsulfuron WP. In the wheat plots with wild oat, the choice of5%pinoxaden900mL/hm2or40%of toluene oxadiazon1125mL/hm2, added water300kg/hm2and foliagesprayed at the seedling stage;In the wheat fields with Wild oats and broadleaf weeds, thechoice of75%oxime oxadiazon�'bromobenzene Clear900-1800g/hm2disposable applyed,the control effect was high to grass weeds and broadleaf weed;In the plots with annual weedssuch as Elsboltzia densa Benth, Thlaspi caerulescens, Rorippa montana(Wall.), after theapplication of24%azole grass. benzene Sulfosulfuron WP120.00-150g/hm2, the controleffect was significant not only for the the annual weeds but also for the perennial weedsCephalanoplos.30%tribenuron�'Bensulfuron metsulfuron�'chlorofluorocarbons topiramateoxyacetate WP600mL/hm2showed significant control effect to the annual weeds Elsboltziadensa Benth, Euphorbia helioscopia,Rorippa montana(Wall.),and it’s also effective toSonchus brachyotus D C.5、According to the occurrence characteristics of spring wheat fields weeds in ourprovince, efficacy trials and demonstration of the Home-made combining herbicide7%Maikuojing were tested, the results showed combining herbicide130g/666.7m2were sprayedduring3-4leaf stage of spring wheat with15kg water, the control effect to broadleaf weedswas up to90%, which increased by15-20percent compared with the common herbicide72%2.4-D butyl EC. Add the pesticide synergistic additives SDP or BCM-101, F-101inMaikuojing could maintain significantly herbicidal effect and reduce20-30%dosage ofherbicide.