Resistance Detection of Scirpus juncoides Roxb. to Pyrazosulfuron-Ethyl and the Screening of Herbicides in Rice Fields from Heilongjiang Province

In order to promote the resistance control of Scirpus juncoides Roxb. in Heilongjiang rice region, this study aims to clarify the resistance level of S. juncoides in rice fields from Heilongjiang Province to pyrazosulfuron-ethyl and screen effectively herbicides as a substitute for pyrazosulfuron-ethyl in controlling S. juncoides. Whole plant dose response was used to detect the resistance of 18 S.juncoides Roxb. populations which were collected from Heilongjiang Province to pyrazosulfuron-ethyl. The control efficacy of 9 herbicides against S. juncoides was tested by greenhouse experiments and field trials. The results of whole plant dose response showed that there were four populations out of eighteen tested populations which were resistant to pyrazosulfuron-ethyl and the resistance indexes of resistant S.juncoides populations including Sj6, Sj7, Sj8 and Sj11 were 7.48, 13.60,11.42 and 10.41,respectively. In addition, the resistance indexes of other 13 sensitive S.juncoides populations were 2.03-3.16. The greenhouse and field trials showed that the control effect of 6 herbicides were all better than pyrazosulfuron-ethyl 10% WP, in which the control efficacy of 3 herbicides including metazosulfuron 33% WG, benzobicylon 25% SC and MCPA·bentazone 460 g·L^-1 SL on weed density and fresh weight after spraying 30 d were all greater than 90%. In summary, because the resistance of some S. juncoides populations in rice fields frome Heilongjiang Province to pyrazosulfuron-ethyl has been from low to medium level, we suggest that S. juncoides in rice fileds could been controlled by applying metazosulfuron 33% WG, benzobicylon 25% SC and MCPA·bentazone 460 g·L^-1 SL.