贵州烟草黑胫病菌对甲霜灵的抗药性测定

Drug Resistance of Phytophthora nicotianae Against Metalaxyl(WP) in Guizhou

为评估贵州烟草黑胫病菌对甲霜灵的抗药性，采用菌落生长速率法，测定了贵州省8个市（州）采集分离的42株烟草黑胫病菌菌株对甲霜灵的抗性。结果表明：贵州8个市（州）菌株的 EC50值为0．2130～4．2497μg/mL，平均值为1．4256μg/mL；毕节市菌株平均 EC50值为0．7158μg/mL，对甲霜灵最敏感，平均抗性倍数为3．655，抗药性最弱；黔西南州菌株平均EC50值为1．4562μg/mL，对甲霜灵表现为不敏感，平均抗性倍数为9．13，抗药性最强。结论：贵州省大部分地区的烟草黑胫病菌已对甲霜灵产生抗性，建议轮换或停止施用。

42 P.nicotianae strains isolated from tobacco plants of 8 cities （prefectures ） were inoculated on culture dishes with different 5 8% Metalaxyl concentrations to study the drug resistance of Phytophthora nicotianae against Metalaxyl by the colony growth rate method.EC50 of strains from 8 cities （prefectures）is 0.213 0~4.249 7μg/mL and the average EC50 is 1.425 6μg/mL.The average EC50 of Bijie strains with 3.655 average resistance times is 0.715 8μg/mL and is sensitive to Metalaxyl.The average EC50 of Qianxinan strains with 9.13 average resistance times is 1.4562μg/mL and is insensitive to Metalaxyl.In conclusion,Metalaxyl should be alternately applied or not be applied in tobacco cultivation because P.nicotianae has drug resistance against Metalaxyl in most tobacco cultivation areas of Guizhou.