Evaluation of Three in-season Tests for Rapidly Detecting Resistance to Acetolactate Synthase Inhibitors in Schoenoplectus juncoides

Abstract

Schoenoplectus juncoides is a noxious weed in paddy field of Korea. The excessive and unreasonable use of acetolactate synthase (ALS)-inhibiting herbicide caused the evolution of herbicide-resistant S. juncoides. As a part of the management of ALS-inhibiting herbicide resistance, early detection of the ALS-inhibiting herbicide resistance in S. juncoides is necessary. In this study, we evaluated three methods of rapidly detecting ALS-resistance in S. juncoides, including the cutting root test, cutting shoot test, and resistance in-season quick (RISQ) test. Three herbicide-resistant populations of S. juncoides (GR, 217R, and WR) and one susceptible population of S. juncoides (HS) collected from the Chungcheongnam-do and Jeollabuk-do of Korea served as experimental materials for the evaluation of three resistance test methods established by previous studies. In the three test methods, the GR and 217R were confirmed as resistant to flucetosulfuron and susceptible to penoxsulam. The WR was highly resistant to flucetosulfuron and penoxsulam. All the three resistance test methods have been successfully applied for identifying the ALS-inhibiting herbicide-resistant S. juncoides in-season. Especially, the result of cutting roots test demonstrated that the GR, 217R, and WR biotypes were highly resistant to flucetosulfuron with the R/S ratios of 34, 100, and 1852, respectively based on GR50. The WR biotype was highly resistant to penoxsulam with the R/S ratio of 912, whereas the GR and 217R biotypes were susceptible to penoxsulam. These inseason quick tests are likely to contribute to the use of effective herbicide in crops leading to decreased costs of labour and inputs in paddy field, and increased profits.