大白菜霜霉病菌寄生霜霉对氟吡菌胺的敏感性

为探明大白菜霜霉病病原菌寄生霜霉Peronospora parasitica对氟吡菌胺的敏感性,采用凹玻片保湿法和离体子叶浸泡法测定了氟吡菌胺对寄生霜霉不同生长发育阶段的抑制作用。结果表明:氟吡菌胺对寄生霜霉孢子囊萌发、芽管伸长、病斑扩展、孢囊梗形成及孢子囊产生均有不同程度的抑制作用,其中对孢子囊萌发和芽管伸长的抑制效果最显著,EC50值分别为0.113 3和0.291 8μg/m L;当氟吡菌胺质量浓度为8.00μg/m L时,对病斑扩展和产孢量的抑制率分别达到86.08%和72.48%,且对孢囊梗的产生也有显著的抑制作用。选用离体子叶浸泡法,测定了氟吡菌胺对从山东省不同地区采集分离的60株寄生霜霉菌株的毒力,发现菌株之间对药剂的敏感性差异较小,敏感性频率呈近似正态分布,其EC50值范围为0.163 2~0.802 2μg/m L,因此可以将其EC50平均值0.405 3μg/m L作为寄生霜霉对氟吡菌胺的敏感基线。

Sensitivity of Chinese cabbage downy mildew pathogen Peronospora parasitica to fluopicolide

To demonstrate the sensitivity of Chinese cabbage downy mildew pathogen Peronospora parasitica to fluopicolide, concave-slide moisturizing method and cotyledon in vitro soaking method were used to test the inhibiting effect of fluopicolide on different development stages of P.parasitica. The results showed that fluopicolide had inhibitory activity on sporangium germination, germ tube elongation, lesion expansion, sporangiophore emergence and sporangium production of P.parasitica to different extents, among which the inhibition of fluopicolide on sporangium germination and germ tube elongation was the most significant, with EC50 values of 0.113 3 and 0.291 8 μg/mL, respectively. The inhibition rates of fluopicolide at 8.00 μg/mL on lesion expansion and sporangium production of P.parasitica were 86.08% and 72.48%, respectively, and the inhibition on sporangiophore emergence was also significant. At the same time, cotyledon in vitro soaking method was used to test the toxicity of fluopicolide to 60 isolates of P.parasitica collected and isolated from different areas of Shandong province. The results indicated that the difference in sensitivity of the 60 isolates to the fungicide was small, the sensitivity frequency showed a nearly Gaussian distribution, and the EC50 values were in the range of 0.163 2-0.802 2 μg/mL, suggesting the EC50 mean value of 0.405 3 μg/mL could be used as the sensitivity baseline of P.parasitica to fluopicolide.