马铃薯晚疫病菌在内蒙古和甘肃的交配型分布及对几种杀菌剂的敏感性

1997-2001年在内蒙古自治区和甘肃省马铃薯主产区采集马铃薯晚疫病菌并进行了交配型和药剂敏感性测定。结果为：采自内蒙古的143株菌中有140株是典型A1交配型、3株是可自育的A1交配型；采自甘肃的41株菌中有40株是典型A1交配型、1株为可自育的A1交配型；二省都未发现A2交配型。表明内蒙古和甘肃马铃薯主产区的晚疫病菌以A1交配型占绝对优势。对甲霜灵（metalaxyl)的敏感性测定显示：内蒙古菌株中有50．8％表现高度抗性、42．5％表现中度抗性、只有6．7％表现敏感，说明内蒙古马铃薯主产区的晚疫病菌普遍对甲霜灵具有了抗性；甘肃的菌株中，26．8％表现高度抗性、29．3％表现中度抗性、43．9％表现敏感；同时发现甲霜灵可刺激某些技性菌株的生长。试验还测定了35株菌对烯酰吗啉(dimethomarph)和腈嘧菌脂(mzoxystrobin)的敏感性：其中对烯酞吗啉表现敏感的占94％、中度敏感的占6％；对腈嘧菌脂敏感的占71．4％，中度敏感的占28.6％；未发现对二种药剂高抗或不敏感菌株，且烯酰吗啉和腈嘧菌脂与甲霜灵均无交互抗性。

Mating type distribution and sensitivity to several chemicals of Phytophthora infestans from Inner Mongolia and Gansu Province, China

The isolates of Phytophthora infestans were collected from Inner Mongolia and Gansu province from 1997 to 2001. The mating type and chemical response of these isolates were then determined. Among 143 isolates from Inner Mongolia, 140 belonged to A1 mating type, and the other three were self fertile isolates of A1 mating type. Among 41 isolates collected from Gansu, 40 of which belonged to A1 mating type, and 1 was self fertile isolate of A1 mating type. No isolate of A2 mating type was detected. Of 120 isolates from Inner Mongolia were tested on the sensitivity to metalaxyl, 50.8% were highly resistant, 42.5% were intermediate resistant, and 6.7% were sensitive.For other 41 isolates from Gansu, 26.8% were highly resistant, 29.3% were intermediate resistant, and 43.9% were sensitive. Also it was found that the vegetative growth of some resistant isolates was stimulated by metalaxyl. These results showed that the resistant isolates predominated in potato major producing areas in Inner Mongolia. The sensitivity of 35 isolates to dimethomorph and azoxystrobin with different levels of metalaxyl resistance were determined, 94% of which were sensitive and 6% were intermediate sensitive to dimethomorph, while 71.4% were sensitive and 28.6% were intermediate sensitive to azoxystrobin. No isolate resistant to dimethomorph or azoxystrobin was detected, and the resistance to metalaxyl did not correlate to the resistance to dimethomorph or azoxystrobin.