Studies on biological characteristics of Septoria dearnessii

The biological characteristics of the pathogen was studied systematically.The results showed that the temperature rage for mycelium growth and sporulation was from 10 to 35 ℃ and the optimum temperature was 25 ℃ The most suitable pH value was 5-7.The pathogen could grow and sporulate well on PDA.The optimum carbon sources was sucrose,and the most suitable nitrogen sources was ammonium nitrogen.The light had not remarkable effect on the mycelium growth and sprulation.Conidia were able to germinate in sterile deionized water but at a low percentage,sugar and host juice stimulated conidial germination of the pathogen.Conidia germinated at 10℃ to 35℃,with optimum temperature between 25℃and 28℃.The optimal relative humidity was above 93 %,and the maximum rate of spore germination in water.The optimum pH value for sporulation was 5-7.In suitable condition,germination of conidia started within 8 hours and the percentage of germination reached above 90 %.The light had not substantial effect on spore germination.The lethal temperature of conidia was 50℃(10min).