马铃薯晚疫病菌对甲霜灵和霜脲氰的敏感性检测

2003 ~2004年从内蒙古和黑龙江省共采集分离了127株马铃薯晚疫病菌Phytophthora infestans,并在离体条件下测定了这些菌株对甲霜灵和霜脲氰的敏感性。结果表明:在2003年分离的内蒙菌株、2003年及2004年分离的黑龙江菌株中对甲霜灵敏感(MS)的菌株频率分别为86.2%、13.8%、17.8%;虽然霜脲氰在这些地区使用近10年,但病菌群体对该药剂的敏感性没有下降,EC50值分布于0.10 ~0.35 μg/mL之间,平均EC50值为0.20(±0.06)μg/mL,不同敏感性的菌株频率呈连续的单峰曲线分布,未出现敏感性下降的抗药性亚群体,可作为马铃薯晚疫病菌对霜脲氰抗药性监测的敏感性基线;此外,马铃薯晚疫病菌对甲霜灵和霜脲氰之间没有交互抗药性,霜脲氰对抗甲霜灵和野生敏感菌株具有相同的活性。

Detection on the Sensitivity of Potato Phytophthora infestans to Metalaxyl and Cymoxanil

In 2003 and 2004, 127 Phytophthora infestans isolates were sampled from Inner Mongolia and Heilongjiang, China, their sensitivities to metalaxyl and cymoxanil were determined in vitro. The results showed that the metalaxyl-sensitive(MS) isolated in 2003 from Inner Mongolia, 2003 and 2004 from Heilongjiang, covered 86.2%, 13.8% and 17.8%,respectively. Although cymoxanil has been used nearly for 10 years in these areas, but no any decreasing in sensitivity of P.infestans populations has been detected. Their EC50 values for cymoxanil ranged from 0.10 μg/mL to 0.35 μg/mL,the mean EC50 value (±SD) was 0.20(±0.06) μg/mL exhibited unimodal distribution of sensitivity, which could be used as the baseline-sensitivity for monitoring the field resistance development in the future. There was no cross-resistance between metalaxyl and cymoxanil in field populations of P.infestans. Cymoxanil gave equal effect on both metalaxyl-resistant and wild-sensitive isolates.