分离自黄瓜的多主棒孢霉不同表型菌株对杀菌剂的敏感性

【目的】通过对分离自黄瓜的多主棒孢霉不同表型菌株适宜生长温度、产孢量等表型特征和对8种杀菌剂的敏感性研究,为多主棒孢霉侵染引起的黄瓜叶斑病和茎疫病的化学防治提供技术支持。【方法】采用温度梯度法测定病菌适宜生长温度;采用PDA培养基25°C黑暗培养5 d和21 d,计测不同表型菌株单位面积产孢量;采用含药平板法测定不同表型菌株对8种杀菌剂的敏感性。【结果】分离自黄瓜的多主棒孢霉不同表型菌株适宜生长温度为25-30°C;在PDA平板25°C黑暗培养5 d,气生菌丝稀少型菌株cu-4、cu-5即大量产孢,产孢量明显多于气生菌丝丰茂型菌株;在试验浓度下,5个试验菌株对8种杀菌剂的敏感性依次为:代森锰锌氟硅唑戊唑醇苯醚甲环唑速克灵百菌清嘧菌酯多菌灵。【结论】分离自黄瓜的多主棒孢霉不同表型菌株在适宜生长温度、菌丝生长速度、产孢量及对杀菌剂的敏感性等方面均存在差异。在试验浓度下,供试菌株对多菌灵和嘧菌酯的敏感性极低(抑制率40%),这2种杀菌剂已失去对该地区黄瓜褐斑病的防控作用。

Fungicide sensitivity of Corynespora cassiicola strains with different phenotypes isolated from cucumber in Baiyin of Gansu

Objective] Via researches on phenotypic features (optimal growth temperatures, sporulation quantity, etc.) and fungicide sensibility of five strains of Corynespora cassiicola with different phenotypes isolated from cucumber in Gansu Province, to provide technical support for control of cucumber Corynespora leaf spot and stem blight. Methods] The optimal growth temperatures were evaluated by temperature gradient method; The sporulation quantity was assessed by conidia yields per unit area on PDA plate; Fungicide sensitivity of Corynespora cassiicola strains was assessed by amendment plate method, autoclaved PDA media were amended prior to pouring with 8 different fungicides. Results] The optimal growth temperatures of all the five strains were among 25?30 °C; Conidia amounts of the strains with scanty aerial hyphae were significantly more than the strains with luxuriant aerial hyphae on PDA plate (cultured 5 d at 25 °C); Under test concentrations, the sensitivity of the five tested strains of Corynespora cassiicola to eight fungicides successively were: mancozeb>flusilazole>tebuconazole>difenoconazole>procymidone>chlorothaloni>azoxystrobin>carbendazim. Conclusion] Different phenotypic strains of Corynespora cassiicola isolated from cucumber were different in optimal colonial growth temperatures, growth speeds, sporulation quantity and fungicide sensitivity. At the tested concentrations, the strains showed very low sensitivity to carbendazim and azoxystrobin (inhibition rates<40%), which implied that the two kinds of fungicides had lost its effect on control of cucumber Corynespora leaf spot and stem blight in the region.