Study On The Resistance Of Beckmannia Syzigachne Steud. To Fenoxaprop-P-Ethyl And Control Methods In Rice And Wheat Succession Cropping Field In Southern Area In Jiangsu Province

Beckmannia syzigachne, is a primary weed in wheat field after rice and rape fieldin the Yangtze valley and southwest area in China. In traditional agricultural times,cultivation methods are primary approach adopted to control weed occurrence anddamage, while in modern agriculture, chemical herbicides are the leading alternativesand these herbicides often used in two forms: soil and foliar treatments.Fenoxaprop-p-ethyl, a foliar treatment herbicide, has been used to control B.syzigachne in wheat field in recent years. However, the frequent application of thisherbicide has resulted in the evolution of resistant B. syzigachne,higher applicationdoses and lower controlling efficacy.In this paper, B. syzigachne, collected from field where rice and wheat were grew inrotation in Lianhu Farm, was selected as a main research object to study on itsresistance level to fenoxaprop-p-ethyl and controlling technology. The affection ofdifferent leaf stage, different continuous application years on the resistance level of B.syzigachne to fenoxaprop-p-ethyl, and the effect of resistant population on wheatyield were studied. In addition, the soil and foliar treatments which can effectivelycontrol B. syzigachne and other effective cultivation measures have been evaluated.The resistance level of B. syzigachne, collected from wheat fields wherefenoxaprop-p-ethyl had been applied for different years were assay. The resultsdemonstrated that B. syzigachne has evolved resistance to this herbicide and theresistance indexes of the weed, to which fenoxaprop-p-ethyl were applied for 3, 5 and9 years were 5.27, 8.01 and 21.59, respectively.The resistance level of B. syzigachne to fenoxaprop-p-ethyl at different leaf stagewas evaluated. The results showed that the resistance has occured in field where riceand wheat were grown in rotation and fenoxaprop-p-ethyl had been applied for 8years continuously. The resistance indexes of B. syzigachne at 3-, 1-, and 5-leaf stagewere 6.49, 12.24, and 27.12, respectively. The resistance level of B. syzigachne, which was collected from wheat field nearbythe Lianhu farm were investigated. The results revealed the occurrence of B.syzigachne population resistant to fenoxaprop-p-ethyl with different resistance level.The resistance indexes of Dantu, Wujing, Jingtan and Jurong populations were 6.98,9.30, 17.48 and 12.50, respectively.The results of the resistance level obtained by foliar sprayer were agreed with thatin laboratory.By observation to the resistance of Beckmannia syzigachne, it was found that thebiomass of susceptible population was greater than that of resistant one when theherbicide was not used, and the inhibition degree of fenoxaprop-p-ethyl to resistantpopulation was less than that to susceptible one.The effect of resistant B. syzigachne to wheat yield was evaluated. The resultsshowed that a remarkable correlation was obtained between the density of B.syzigachne in per area and its inhibition rate to wheat tiller, as well as a significantcorrelation was obtained between the fresh weight of B. syzigachne in per area and itsinhibition rate to wheat yield.The control measures to resistant B. syzigachne in wheat field were studied and theresults showed that isoproturon, butachlor and acetochior can be selected as soiltreatment herbicides in fields, as well as mesosulfuron can be used as foliar herbicidewhich was an alternative of fenoxaprop-p-ethyl in order to prevent the resistance of B.syzigachne to fenoxaprop-p-ethyl from further increasing as well as to prolong itsapplication life.