Resistance Monitoring And Management Of Weeds In Wheat Field

Alopecurus aequalis,Alopecurus japonicas,Beckmannia syzigachne,Galium aparine and Vicia sativa are major weeds in wheat field of the lower-middel reaches of the Yangtze River.Because of the long-term application of herbicides with the mono-mechanism,herbicide resistance weeds appeared in fields.Certain A.aequalis,A.japonicas and B.syzigachne weed species had been reported to be resistant to fenoxaprop-P-ethyl,and certain G.aparine to be resistant to tribenuron-methyl.In order to estimate resistant change of weeds in field,bioassay were conducted to evaluate the dose-response to fenoxaprop-P-ethyl of A.aequalis,A.japonicas,B.syzigachne populations,and tribenuron-methyl of G.aparine,V.sativa populations.1.Resistance surveyIn this paper,the sensitivities of A.aequalis,A.japonicas,B.syzigachne populations to fenoxaprop-P-ethyl,and G.aparine,V.sativa populations to tribenuron-methyl,were determined by seeds bioassay.Results of grass weeds are listed as follows:Among 85 tested grass weed populations in 2013,39 populations were resistanced to fenoxaprop-P-ethyl,with the resistant percentage of 45.88%.And these resistant populations were distributed mainly over Yangzhou,Changzhou,Lianyungang and Huaian.Among 23 tested A.aequalis populations,12 populations were resistant to fenoxaprop-P-ethyl,with the resistant percentage of 53.17%,and resistant populations were distributed mainly over Lianyungang and Yangzhou.Among 23 tested A.japonicas populations in 2013,9 populations were resistant to fenoxaprop-p-ethy,with the resistant percentage of 39.13%,and resistant populations were distributed mainly over Changzhou and Yangzhou.Among 39 tested B.syzigachne populations in 2013,18 populations were resistant to fenoxaprop-P-ethyl,with the resistant percentage of 46.15%,and resistant populations were distributed mainly over Yangzhou and Changzhou.Among these main distributing areas of resistant grass weed populations,Yangzhou and Changzhou had resistant A.aequalis,A.japonicas and B.syzigachne,with unusually high rate of 77.27%in Yangzhou and 66.67%in Changzhou,which indicated that the resistance was quite heavily in Yangzhou and Changzhou.In Huaian,the ratio of resistant B.syzigachne is 46.15%,and all of them had reached high level of resistance,which showed that B.syzigachne resistance has been quite heavily in Huaian.Results of broad-leaved weeds are listed as follows:Among 12 tested G.aparine populations in 2013,7 populations were resistant to tribenuron-methyl,with the resistant percentage of 58.33%,and resistant populations were distributed over Yancheng,Ganyu,Yangzhou of Jangsu province and Chouzhou of Anhui province.The population 13JYGY-3 collected from Yangzhou City was the most resistant one with an ED50 value of 1364.70 g a.i./ha,and the R/S ratio was as high as 401.38.Among 8 tested V.sativa populations in 2013,only 1 population was resistant to tribenuron-methyl with an ED50 value of 45.96 g a.i./ha,and the R/S ratio was as high as 10.42.2.Resistance monitoringWhole-plant bioassay experiments were conducted to monitore the resistance level of weeds.The distributing areas of resistant grassy populations showed no sign of narrowing,and the level of resistance showed no sign of declining.The monitoring experiments also indicated that continued to use fenoxaprop-P-ethyl or tribenuron-methyl,resistance of weeds would go up,and used other herbicides,resistance would decrease.3.Screening of chemical herbicides to control resistant weedsAvailable single-dose and mixed herbicides were studied to controlment resistance weeds.All of the soil treating herbicides flufenace,diflufenicant,acetochlor,trifluralin,isoproturon,chlortoluron could control fenoxaprop-resistant grass weeds.Among leaf treating herbicides,pyroxsulam,mesosulfuron,pinoxaden,clodinafop-propargyl could control resistant A.aequalis populations,but couldn't control resistance A.japonicas and B.syzigachne populations.Soil treating herbicides diflufenicant,fluoroglycofen and leaf treating herbicedes florasulam,carfentrazon could control resistance G.aparine populations.Flufenace·diflufenicant could control resistance grass weeds.And mesosulfuron.pinoxaden could control susceptible grass weeds,so that to delay the development of herbicide resistance of weeds.4.Agricultural measures to manage resistant weedsAlso,this paper explored the effect of temperature,illumination,sowing depth and storage time in seedling of B.syzigachne.Under condition of 12h light/12h dark,20/15?,different B.syzigachne biotypes seeds all reached the highest germination rate,and the germination rate of resistance biotypes showed no significant difference with susceptible biotype.Germination rate of seeds from the biotype with 1781 mutation was lower than the susceptible biotype's in 25/20?.Germination rate of seeds from the biotype with 2041 mutation was lower than the susceptible biotype's in 25/20? or whole light.Germination rate of seeds from the biotype with 2096 mutation was lower than the susceptible biotype's in 15/10?.Germination rate of seeds from the biotype with 2027 mutation was lower than the susceptible biotype's in 25/20 ?,15/10 ? and whole light.Emergence rates of resistance biotypes showed no significant difference with susceptible biotype with different sowing depth.Stored at room temperature for 2 years,emergence rates of differente B.syzigachne biotypes seeds all declined.Emergence rates of seeds from the biotype with 2041 mutation was lower than the susceptible biotype's,and other's showed no significant difference with susceptible biotype.The effect of different tillage methods against resistance weeds was studied in field.And result indicated that the grass weed quantity and resistance level of grass weeds would decline if conducting deep ploughing at least once after wheat harvested or rice harvested.