杀菌剂对辣椒疫霉菌的毒力及其所致番茄猝倒病的控制效果研究

实验室接种条件下比较了6种杀菌剂对辣椒疫霉菌Phytophthora capsici Leonian引起的番茄猝倒病的控制作用,室内测定了其对致病菌菌丝生长、孢子囊形成、释放游动孢子3种不同菌态的毒力。结果表明:在对番茄安全的剂量下进行土壤处理时, FDA3 霉灵、稻瘟灵对番茄猝倒病的防效为80%~90％,霜霉威和代森锰锌的防效为60%~70％,甲霜灵和异菌脲的防效在50％左右;供试杀菌剂浸种处理对番茄猝倒病的防效都较低,均在60％以下。甲霜灵对致病菌菌丝生长、孢子囊形成、释放游动孢子的毒力最高,EC50值分别为0.304、0.742和2.725 mg/L; FDA3 霉灵、稻瘟灵对致病菌孢子囊形成的毒力较高,EC50值分别为0.875和2.888 mg/L,但对菌丝生长和释放游动孢子的EC50 值均在20 mg/L以上;代森锰锌的毒力中等,对3种菌态的EC50值分别为3.402、10.243和23.561 mg/L;霜霉威和异菌脲对病原菌3种不同菌体形态的毒力都较低,EC50＞100 mg/L。

The Control Effect and Toxicity of Fungicides on Tomato Seedling Damping-off Caused by Phytophthora capsici Leonian

In lab and greenhouse, the control effects of six fungicides on tomato seedlings (damping-off) caused by Phytophthora capsici Leonian and the impacts of fungicides to the growth of mycelium, the producing of sporangia, the releasing of zoospores of the pathogen were (studied.) As treated by soil-soaking, the control effects of hymexazol and isoprothiolane on the damping-off disease could reach 80% above, propamocarb and mancozeb could reach 60%~70%, and the effects of metalaxyl and iprodione only 50%. When treated with seed-soaking, the (control) effect of six tested fungicides was all lower than 60%. Metalaxyl had the highest toxicity to the growth of mycelium, the producing of sporangia, the releasing of zoospores of P. capsici, their EC_(50) values were (0.304,) (0.742) and (2.725 mg/L.) The toxicities of (hymexazol) and isoprothiolane on the producing of sporangia were also higher, and their EC_(50) were 0.875 and (2.888 mg/L), respectively, but their toxicities to the growth of mycelium and release of zoospores were lower than that of mancozeb. The next was mancozeb, which EC_(50) (values) to mycelium growth, sporangia producing and zoospores releasing of pathogen were (3.402), (10.243) and (23.561 mg/L) respectively. The toxicities of propomocarb and (iprodione) were the lowest, their EC_(50) values were more than 100 mg/L.