Biological Characterization Of Bipolaris Maysdis And Curvularia Lunata And Screening For Effective Fungicides And Biocontrol Agents

Maize is important for crop production, industrial raw materials and animal feeds in China. The maize’s growing area and yield is the first one followed by rice and wheat. Maize disease especially the Bipolaris maydis Nisik & Miy and Curvularia lunata Boedijn are the important factors affecting maize quality and production. The problem became worse because of knowing little about the pathogen and lacking effective control methods.In this study, Pathogen Bipolaris maydis and Curvularia lunata were isolated and characterized. Effective agrochemicals and bio-control bacterial strains were screened. The main results obtained in this study are listed as follows:Diseased leaf and rhizosphere samples were collected from Zaozhuang, Taian, Linyi, Liaocheng. According to the morphological and ITS cluster analysis, Pathogen were Bipolaris maydis Nisik & Miyake and Curvularia lunata Boedijn.Pathogen Bipolaris maydis and Curvularia lunata were isolated and their biological properties were characterized. Spores of the Bipolaris maydis could germinate between 5-35°C, in which the germination rate could reach 100% at 25°C. With 100% relative humidity(RH), spores started to germinate after 2 hours and germination rate reached 100% after 8 hours. No significant difference was found with different light treatment on the spores’ germination. Hyphal could grow between 15-35°C, moreover, 25-30°C was the most suitable temperature for hyphal growth.Curvularia lunata could germinate between 10-35°C; the germination rate could reach 100% at temperature between 25-30°C. Similar to Corn southern leaf blight, spores were starting germination at RH 100% for 2 hours. The germination rate reaches 100% after incubating 10 hours at RH 100%. No obvious difference was found with different light treatment on the spores’ germination. Hyphal could grow between 15-35°C, in which 30°C was the most suitable temperature for hyphal growth.Nine agrochemicals were found which can suppress the hyphal growth of 35°C, in which 30°. In which 30% Triflumizole wettable powders aqueous solutions showed the best suppression effect with EC50 value of 0.0277mg/L. The second one was 42.4% Imidazole fluorine amide suspending agent with EC50 value of 0.1987mg/L.Eight agrochemicals showed suppression ability on hyphal growth of Curvularia lunata. The 30% Triflumizole wettable powders aqueous solutions Curvularia lunata. The 30% Triflumizole wettable powders aqueous solutions has the best performance with EC50 value of 0.058mg/L, followed by 30% benzyl-kresoxim-methyl suspending agent with EC50 value of 0.1279mg/L.Five and six bacterial species have shown ability to inhibit the hyphal growth of Corn southern leaf blight and Curvularia lunata, respectively. Four(designated as CLS23, CLS11, CLS20 and CLS4) which have the best performance for both pathogen were Bacillus amyloliquefaciens, Burkholderia cepacia, Burkholderia cenocepacia and Paenibacillus jamilae.Based on the sequence of 5.8S and ITS of Bipolaris maydis Nisik & Miy and Clg2 p of Curvularia lunata Boedijn,we designed specific primer pairs BMF-3,BMR-3 and CLF-4,CLR-4. Bipolaris maydis Nisik & Miy,Clg2 p of Curvularia lunata Boedijn and Exserohilum turcicum(Pass.)Leonard et Suggs were used as templates to detect the specific of the primer pairs,conventional PCR test results showed that the specific primers designed could effectively amplify the DNA of Bipolaris maydis Nisik & Miy and Curvularia lunata Boedijn and gained about 200 bp fragments.