一种测定大白菜霜霉病菌对甲霜灵敏感性方法的建立及应用

Establishment and application a method for testing the sensitivity of Peronospora parasiticato metalaxyl

建立了一种新方法—离体子叶浸泡法并用于大白菜霜霉病菌对甲霜灵敏感性的检测。离体子叶在含有0.005%吐温20和0.1%丙酮的甲霜灵中浸泡3h后,接种浓度为1×104孢子囊/mL的大白菜霜霉病菌孢子囊悬浮液,保湿培养6d后观察子叶发病状况。采用离体子叶浸泡法测定了50株大白菜霜霉病菌对甲霜灵的敏感性,结果显示部分大白菜霜霉病菌菌株对甲霜灵的敏感性降低,有抗药性亚群体出现。研究表明离体子叶浸泡法重复性好,具有较高的敏感性和精密度,符合生产实际,适用于大白菜霜霉病菌对杀菌剂的敏感性检测。

A new method, cotyledon in vitro immersion method, was established and used for detecting the sensitivity of Chinese cabbage downy mildew pathogen （Peronospora parasitica） to metalaxyl. After soaked for 3 h in metalaxyl with 0. 005% Tween 20 plus 0.1% acetone, the cotyledons in vitro were artificially inoculated with sporangium suspension（1 × 10^4 sporangium/mL）, then incubated in the moist chamber, and the disease severity was checked after 6 d of culture. Sensitivity of 50 P. parasitica strains to metalaxyl was tested. The results revealed that sensitivity of some strains decreased significantly and resistant subpopulations emerged. The studies indicated that the method was suitable for the sensitivity detection of P. parasiticato fungicides and in accord with practice for its good repeatability and higher sensitivity and precision.