中国河南省小麦纹枯病菌对井冈霉素及甲基立枯磷的敏感性

为明确中国河南省小麦纹枯病菌对井冈霉素及甲基立枯磷的敏感性，采用菌丝生长速率法测定了两种药剂对采自该省15个地市的98株病原菌菌丝生长的毒力。结果显示:井冈霉素和甲基立枯磷对供试菌株的EC₅₀值范围分别在0.023~0.852和0.035~0.512 μg/mL之间；其敏感性频率分布图显示，病原菌群体中虽已出现对井冈霉素敏感性下降的亚群体，但77.6%和99.0%的菌株对井冈霉素和甲基立枯磷的敏感性频率仍呈正态分布，因此可将此部分菌株的平均EC₅₀值（0.424±0.081）和（0.124±0.043）μg/mL分别作为小麦纹枯病菌对井冈霉素和甲基立枯磷的敏感基线；井冈霉素的平均EC₅₀值是甲基立枯磷的3倍，表明该病原菌对甲基立枯磷更为敏感；不同地理来源病原菌群体间对井冈霉素和甲基立枯磷的敏感性均存在显著的地域性差异；小麦纹枯病菌对两种杀菌剂的敏感性之间无明显相关性。研究结果可为河南省小麦纹枯病的可持续防控提供理论依据。

Sensitivity of Rhizoctonia cerealis to jinggangmycin and tolclofos-methyl in Henan province in China

The sensitivities of Rhizoctonia cerealis to jinggangmycin and tolclofos-methyl were determined by measuring the mycelial growth on the fungicide-amended media using 98 isolates collected from 15 cities in Henan province. The results indicated that 50% effective concentration (EC₅₀) values of all isolates to jinggangmycin and tolclofos-methyl ranged from 0.023 to 0.852, and 0.035 to 0.512 μg/mL, respectively. The results of the frequency analysis revealed that low sensitivity subcolony to jinggangmycin had been observed in the tested isolates. The mean EC₅₀ values of (0.424±0.081) and (0.124±0.043) μg/mL for 77.6% and 99.0% of all isolates showed a normal distribution, which was treated as the sensitivity baseline of R. cerealis to jinggangmycin and tolclofos-methyl, respectively. The mean EC₅₀ value of jinggangmycin was 3 times higher than that of tolclofos-methyl, which meant that R. cerealis was more sensitive to tolclofos-methyl. The isolates collected from different regions showed different sensitivities. It is noteworthy that the correlation efficient existed between jinggangmycin and tolclofos-methyl was very low, which implied that there was no cross-resistance between those two fungicides. The results provided a theoretical basis for the efficient application of the two fungicides in the control of wheat sharp eyespot in the field of Henan province.