Zhou Feng, Zhang Xiao-Lei, Li Jin-Li, Zhu Fu-Xing
College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
Plant Dis. 2014 Sep;98(9):1221-1226. doi: 10.1094/PDIS-10-13-1072-RE.
The dicarboximide fungicide dimethachlon has been widely used for controlling Sclerotinia sclerotiorum in China for more than a decade. To assess the current status of dimethachlon resistance in S. sclerotiorum in China, 2,424 isolates were collected from disease-infected oilseed rape and soybean plants in five provinces of China in 2011 and 2012, and dimethachlon resistance was monitored by mycelial growth inhibition method on potato dextrose agar (PDA) media. Dimethachlon at 5 μg/ml was used as a discriminatory dose to detect resistance in all isolates, and 50% effective concentration values were determined for all dimethachlon-resistant isolates and some sensitive isolates. No dimethachlon resistance was detected in isolates from Anhui province (eastern China), Gansu province (northwestern China), and Qinghai province (western China). In Hunan province (central China), 3 of 268 (1.12%) isolates collected from oilseed rape plants in 2012 were resistant to dimethachlon, and the resistance ratios for the three resistant isolates were 4.56, 32.70, and 105.53, respectively. In Heilongjiang province (northeastern China), 8 of 243 (3.29%) isolates collected from soybean plants in 2011 were resistant to dimethachlon, with resistance ratios of 5.57 to 94.80; 11 of 409 (2.69%) isolates collected in 2012 were resistant to dimethachlon, with resistance ratios of 3.21 to 9.69. Cross-resistance studies showed that there was positive cross-resistance between dimethachlon and iprodione, procymidone, and the N-phenyl carbamate fungicide diethofencarb. No cross-resistance was found between dimethachlon and carbendazim, tebuconazole, kresoxim-methyl, thiram, and boscalid. Compared with the sensitive isolates of S. sclerotiorum, the field-dimethachlon-resistant isolates were more sensitive to osmotic pressure, grew more slowly on PDA media, and were less pathogenic on leaves of oilseed rape.
十多年来，二甲菌核利这种二甲酰亚胺类杀菌剂在中国已被广泛用于防治油菜菌核病。为评估中国油菜菌核病菌对二甲菌核利的抗药性现状，2011年和2012年从中国五个省份的染病油菜和大豆植株上采集了2424个分离株，采用菌丝生长抑制法在马铃薯葡萄糖琼脂（PDA）培养基上监测对二甲菌核利的抗药性。以5μg/ml的二甲菌核利作为鉴别剂量来检测所有分离株的抗药性，并测定了所有对二甲菌核利有抗性的分离株以及一些敏感分离株的半数有效浓度值。在中国东部的安徽省、西北部的甘肃省和西部的青海省的分离株中未检测到对二甲菌核利的抗药性。在中国中部的湖南省，2012年从油菜植株上采集的268个分离株中有3个（1.12%）对二甲菌核利有抗性，这三个抗性分离株的抗药系数分别为4.56、32.70和105.53。在中国东北部的黑龙江省，2011年从大豆植株上采集的243个分离株中有8个（3.89%）对二甲菌核利有抗性，抗药系数为5.57至94.80；2012年采集的409个分离株中有11个（2.69%）对二甲菌核利有抗性，抗药系数为3.21至9.69。交互抗性研究表明，二甲菌核利与异菌脲、腐霉利以及N-苯基氨基甲酸酯类杀菌剂乙霉威之间存在正向交互抗性。在二甲菌核利与多菌灵、戊唑醇、醚菌酯、福美双和啶酰菌胺之间未发现交互抗性。与油菜菌核病菌的敏感分离株相比，田间对二甲菌核利有抗性的分离株对渗透压更敏感，在PDA培养基上生长更慢，对油菜叶片的致病性更低。
