| In order to clarify the current resistance status of Lolium multiflorum to the herbicides of acetyl CoA carboxylase(ACCase) and acetolactate synthase(ALS), a total of 50 populations were collected in the severe area of L. multiflorum in Zhumadian City, Henan Province and the resistance levels to pinoxaden, clodinafop propargyl and pyroxsulam were determined by the whole plant bioassay method. In addition, isoproturon, diflufenican, flufenacet, pyroxasulfone, diflufenican+isoproturon, and pyroxsulam were selected for bioactivity determination, and field efficacy evaluation were conducted with pyroxasulfone, flufenacet, and pyroxsulam mixed with diflufenican+isoproturon. The results showed that eight populations of L. multiflorum had high resistance to pinoxaden. The GR50(herbicide dose causing growth reduction of fresh weight by 50%) values ranged from 146.67 g(a.i.)·hm-2 456.15 g(a.i.)·hm-2, and the resistance index(RI) ranged from 10.68 to 33.20, accounting for 16% of the tested populations. Thirty one populations showed high level resistance to clodinafop propargyl, with GR50 ranging from 101.82 g(a.i.)·hm-2 446.40 g(a.i.)·hm-2, and RI ranging from 10.36 to 45.41; sixteen populations had high level resistance to pyroxsulam, accounting for 32% of the total. In the bioactivity assays, except for diflufenican and pyroxsulam, the other herbicides(isoproturon, flufenacet, pyroxasulfone, diflufenican+isoproturon) showed high activity against the SC 3 population(the highest level of resistance population), with GR90 values of 1 089.36, 144.43, 51.42 and 568.69 g(a.i.)·hm-2, respectively. Field efficacy results indicated that the mixture of pyroxasulfone and diflufenican+isoproturon provided good control of L. multiflorum at the supplied dose, with fresh weight control efficacy ranging from 94.27% to 100%, and safe to wheat. Therefore, the mixture of pyroxasulfone and diflufenican+isoproturon can be used to control the serious occurrence of L. multiflorum in wheat fields. |
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