7种杀菌剂对玉米大斑病病原菌的毒力测定试验

研究旨在鉴定出玉米大斑病病原菌，筛选出防治玉米大斑病的最佳药剂。试验采用组织分离法对玉米大斑病病原菌进行分离鉴定，用含毒培养基生长速率法测定7 种杀菌剂对玉米大斑病病原菌的抑制效果。经分离鉴定，该病原菌为链格孢Alternaria alternate。毒力测定试验结果表明：药后48 h，异菌脲EC50值为0.27 mg/L，毒力指数最大，对链格孢菌抑制效果非常显著；丙环唑和苯醚甲环唑EC50值为0.51、0.53 mg/L，抑制效果较显著；氟硅唑和嘧霉胺的EC50值为1.66、1.91 mg/L，效果显著；代森锰锌和醚菌酯的EC50值分别为25.82、929.78 mg/L，毒力指数较低，抑制效果差；药后72 h 各药剂对链格孢的抑制效果与药后48 h 抑制效果相似。在7 种杀菌剂中异菌脲对链格孢菌抑制效果最好，当试验浓度为50 mg/L 时，抑制率可达95%。

Toxicity Test on Pathogen of Corn Northern Leaf Blight with Seven Fungicides

The aim of this experiment was to identify the pathogen of Corn Northern Leaf Blight and screen out the best bactericide for controlling Corn Northern Leaf Blight,the method of tissue separation was used to isolate and identify the pathogen, and the culture medium growth rate Method was used to determine the inhibitory effect of seven kinds of fungicides on pathogens of Corn Northern Leaf Blight. the pathogen was identified as Alternaria alternate (Fr.) Keissl, toxicity test results show that: after 48 h, the EC50 of Iprodione was 0.27 mg/L;the virulence index was the highest, and the inhibitory effect was very significant; the EC50 of Propiconazole and Difenoconazole were 0.51 and 0.53 mg/L, and their inhibitory effect were significant; the EC50 of Flusilazole and Pyrimethanil were 1.66 and 1.91 mg / L, and the effects were good; the EC50 of Mancozeb and Kresoxim-methyl were 25.82 and 929.78mg / L, their virulence index were low and inhibitory effects were poor;the inhibitory effect was similar between 72h and 48h;therefore,the inhibition effect of Iprodione on Alternaria was the best among the seven fungicides, When the experiment concentration was 50 mg/L, the inhibition rate was 95%.