Inhibition on Bipolaria maydis and Disease Control on Southern Corn Leaf Blight of Various Fungicides

This study aimed to select effective fungicides for the control of the southern corn leaf blight caused by Bipolaria maydis.Toxicities of various fungicides were determined according to the rates of the mycelial growth and spore germination of B.maydisin media containing the fungicides.The efficacies of the fungicides in controlling the disease were evaluated by apot experimentation.The results showed that 9fungicides,including fluazinam,prochloraz,and difenoconazole,had a strong inhibition effect on the mycelial growth of B.maydis,with EC50 lower than 1μg·mL-1.Chlorothalonil and mancozeb were not effective in retarding the fungal growth,with EC50 of 7.6075 and 12.0671μg·mL-1,respectively.However,chlorothalonil,mancozeb,pyraclostrobin,fluazinam,and iprodione were found highly inhibitive on the spore germination,with EC50 of 0.3565,0.4523,1.7093,2.9763,and 37.5795μg·mL-1,respectively.Other DMI fungicides were low in inhibiting the spore germination,with EC50 above 160μg·mL-1.The control effect of spraying 1,000-time dilution of 50%iprodione SC,600-time dilution of 75% chlorothalonil WP,1,000-time dilution of 80% mancozeb WP,or 2,000-time dilution of 50%fluazinam SC 2hprior to inoculation was greater than 80% on the pathogen.