六省市致病疫霉交配型及其对几种杀菌剂的敏感性

测定了2000-2002年采自四川、重庆、吉林、黑龙江、福建、北京六省(市)致病疫霉菌株的交配型及其对几种杀菌剂的敏感性。结果显示,来自六省市的74个菌株中73株为典型的A1交配型,1株采自四川的菌株为可自育的A1交配型,未发现A2交配型。测定的37株代表菌中,对甲霜灵表现敏感、中抗、高抗的分别占27.0％、27.0％和46.0％。吉林、福建、黑龙江及重庆都存在高抗菌株。研究中还发现甲霜灵可促进部分抗性菌株的菌丝生长。随机抽取15个对甲霜灵表现敏感、中抗和高抗的菌株,测定其对几种杀菌剂的敏感性,结果全部对腈嘧菌酯和烯酰吗啉表现敏感;其中2株对丙酰胺表现敏感,11株表现中抗,2株表现高抗。结果也显示:烯酰吗啉和腈嘧菌酯与甲霜灵之间不存在交互抗性,具有应用潜力。

Mating type of Phytophthora infestans from six provinces (cities) in China and their sensitivity to several fungicides

A total of 70 isolates of Phytophthora infestans were collected from potato in Sichuan, Chongqing, Jilin, Hei-longjiang, Fujian provinces(cities), and 4 from tomato in Beijing from 2000 to 2002. The isolates were assessed for mating type and sensitivity to fungicides. Among them, 73 isolates belonged to A1 mating type, and 1 from Sichuan was self-fertile A1 mating type. No isolates of A2 mating type was detected. Of the 37 isolates tested for sensitivity to metalaxyl, 27.0% was sensitive, 27.0% intermediately resistant, and 46.0% highly resistant. Metalaxyl-resistant isolates were detected in Jilin, Fujian, Heilongjiang provinces and Chongqing City. The results showed that the level of sensitivity to metalaxyl differed among isolates from different provinces (cities). Also it was found that metalaxyl stimulated the vegetative growth of some resistant isolates. The sensitivity of P. infestans to dimethomorph, azoxystrobin and propamocarb was determined by using 15 isolates with different levels of metalaxyl sensitivity. All of them were sensitive to dimethomorph and azoxystrobin. Among them, 2 was sensitive, 11 intermediately resistant and 2 highly resistant to propamocarb. The results also showed that the resistance to metalaxyl did not correlate to the resistance to dimethomorph or azoxystrobin. Dimethomorph and azoxystrobin have potential for control of late blight of potato.