Identification And Biological Characteristics Analysis Of The Pathogen Of Maize Phyllosticta Zeae Leaf Spot Disease

1. Maize leaf spot disease was investigated in Gansu Province and found a newdisease.The disease had been oberved in Lingtai and Lingtao in Gansu province ofChina in2011.It was occurred in Dingxi,Pingliang,Tianshui and Longnan in2012.Thefield disease incidence is about5-40%.2. By analysing morphological character, cultural character and pathogenicity,the fungus should be Phyllosticta zeae.The results indicated that the colonies of P.zeae on PDA culture medium were white and later turned black. Mycelium wasachmmatous or brown, branched and septate. Conidiophore was achromatous ovalcell. Conidiogenous cell was enteroblastic-phialidie(eb-ph).3. Phyllosticta zeae’s biological characteristics showed that the myceliumadapted to grow on PDA, MLPA, OTCA, OA and CMA medium, which could’tproduce pycnidium. But MLPCA medium benefited to produce pycnidium. Theoptimum temperature for mycelial growth, forming pycnidium and conidiagermination were30,25and20℃,respectively. However, the lethal temperature ofmycelial growth reached60℃. Light had a significant influence on mycelial growth,but black light accelerated conidia germination.The optimum pH values for mycelialgrowth, forming pycnidium and conidia germination were six, seven and nine,respectively. Among carbon and nitrogen source, Levulose and L-Asparagine werebest for mycelial growth.4. The fungicide efficiency on controlling the disease was studied on maize leafspot disease in vitro.The fungicides were50%Carbendazim WP,10%DifenoconazoleME,80%Mancozeb WP,98%Tebuconazole ME,20%Propiconazole ME,25%Myclobutanil EC,12.5%Diniconazole WP,95%Hymexazol WP and96.9%Thiophanate-methyl WP.The results showed that nine fungicides have differentinhibitory efforts to mycelial growth of Phyllosticta zeae,the EC50of50%Carbendazim WP,10%Difenoconazole ME,80%Mancozeb WP,98%TebuconazoleME,20%Propiconazole ME,25%Myclobutanil EC,12.5%Diniconazole WP were0.00088μg/mL、0.00112μg/mL、0.00152μg/mL、0.00254μg/mL、0.00703μg/mL、0.26777μg/mL and0.43756μg/mL,respectively.The inhibitory efforts to mycelialgrowth were better than95%Hymexazol WP and96.9%Thiophanate-methyl WP, theEC50were27.09078μg/mL and7.39237μg/mL,respectively.