The Resistance Of Japanese Foxtail (Alopecurus Japonicus Steud.) And Wild Oat (Avena Fatua L.) To Fenoxaprop-p-ethyl And Clodinafop-propargyl

Recently, unsatisfactory control of Japanese foxtail (Alopecurus japonicus Steud.)and wild oat (Avena fatua L.) using fenoxaprop-P-ethyl has been reported from some wheat growing areas including Jiangsu, Hubei, and Henan provinces. It may be due to evolution of herbicide resistance. In this research, We have studied the the resistance level of Japanese foxtail and wild oat populations using whole plant bioassay and seed bioassay, furthermore, the two bioassay methods were also been compared. The objectives of this research were to provide useful information and references for the monitoring and regulation of resistant Japanese foxtail and wild oat populations, and to explore the rapid, accurate diagnosis of resistance in Japanese foxtail and wild oat. The main results are as follows:1 Some Japanese foxtail populations have evolved different resistance to fenoxaprop-P-ethyl and cross-resistance to clodinafop-propargyl, which have never been applied before. Lianhu (LH) and Yixing (YX) populations had the highest resistance to both herbicides. The R/S ratio for fenoxaprop-P-ethyl was 35.64, 14.58 g ai ha^-1, and 16.03, 10.18 g ai ha^-1 for clodinafop-propargyl, respectively. Huangji (HJ), Huahe (HH) were less resistant with 8.38, 4.03 of R:S ratios for fenoxaprop-P-ethyl and 6.17, 5.81 of R:S ratios for clodinafop-propargy. For fenoxaprop-P-ethyl, Damiao (DM), Xianyang (XY), and Jinan (JN) had low resistance with 2.74, 2.52, and 2.11 of R:S ratios, when the other 3 populations had similar sensitivity with R:S ratios were all under 2.00. JN population had low resistance to clodinafop-propargyl with R:S ratio of 2.47, whereas other 5 populations had similar sensitivity and the R:S ratios varied from 1.00 (Daliu, DL) to 1.80 (DM).2 No resistant wild oat populations had been found. However, the sensitivity to both fenoxaprop-P-ethyl and clodinafop-propargy was significantly different during the populations. Jinshuizha (JSZ) population was the most susceptible both to fenoxaprop-P-ethyl and clodinafop-propargyl, giving a 2.46 and 3.65 g.ai.ha^-1 of GR50 values, respectively. Huixian (HX), Ningling (NL) had the lowest sensitivity to both herbicides. For fenoxaprop-P-ethyl, the GR50 values were 15.00, 14.55 g ai ha^-1, which was 6.09 and 5.91 times respectively compared with the JSZ population. For clodinafop-propargyl, the GR50 values were 23.12, 18.38 g ai ha^-1, which indicated HX, NL populations were 6.34 and 5.03 times more tolerance than JSZ populatin. The ranking for sensitivity of other wild oat populations to fenoxaprop-P-ethyl was Damiao (DM)