Studies On The Classification,Biological Character And Pathogenicity Of Pathogen Of Maize Curvularia Leaf Spot In Sichuan

Maize Curvularia leaf spot was listed as a quarantine disease in Sichuan, more than one hundred samples from different area were collected and seventy-eight isolates were obtained for this study. In the present study we had three objectives: first, to identify the species structure of maize Curvularia leaf spot in Sichuan; second, to examine the biological characters of three Curvularia species; and third, to tested the pathogenicity of the pathogen. The results are as follows:1. According to the Ellis'standard, the 78 isolates of Curvularia from different area in Sichuan were classified into 6 species: Curvularia lunata(Warkker)Boedijn, Curvularia lunata var.aeria M.B.Ellis, Curvularia senegalensis(Speg.)Subram, Curvularia pallescens Boedijn, Curvularia clavata Jain and Curvularia ovoidea(Hiroe & watan) Muntanola and Curvulana lunata(Warkker)Boedijn was the dominant species causeing Curvularia leaf spot of maize.2. The effect of temperature , pH, carbon and nitrogen on the growth of 4strains of 3 Curvularia species were examined on plate of PDA. The rang of temperature for growth of the four isolates was 10-35℃, and the optimum temperature for growth was 30-35℃; The rang of pH for growth was 4-12 and the optimum pH value for growth was 6-8; The most suitable carbon source was Polysaccharide, such as inulin; The most suitable nitrogen source was organic nitrogen, such as glycine. Nitrogen source of NH4Cl was not suitable for growth of Curvularia isolates.3. The pathogenicity of twenty-seven isolates were tested on maize plants at seeding and adult stage. According to the amount of spore-production and the size of spot on inoculated maize plants, the pathogenicity of tested isolates could be divided into strong, mid and weak types.