Biological characteristics of the pathogen causing gray leaf spot of loquat

The effect of temperature,pH,light,carbon source,nitrogen source and moisture on the mycelial growth,sporulation and conidial germination of loquat gray leaf spot fungus [Pestalotiopsis eriobotryfolia(Guba) Chen et Chao] was primarily studied.For the mycelia growth of P.eriobotryfolia,the range of temperatures was 8 to 36 ℃,the optimum being 24 ℃;and the range of pH was 3 to 10,the optimum being 5.For the sporulation,the range of temperatures was 8 to 34 ℃,the optimum being 26 ℃;and the range of pH was 3 to 10,the optimum being 4.For the conidial germination,the range of temperature was 8 to 36 ℃,the optimum being 28 ℃;and the range of pH was 3 to 10,the optimum being 5.When the relative humidity reached 100% or in water,the percentage of conidial germination was the highest;the conidia were found not germinated when the RH was below 90%.The maltose,or sucrose could promote the conidial germination.The ammonium sulfate,ammonium phosphate,or ammonium nitrate could inhibit the conidial germination.The lethal temperature for the spores was 50 ℃ maintaining 10 minutes or 55 ℃ maintaining 2 min,while the lethal temperature for the mycelium was 50 ℃ maintaining 15 min or 55 ℃ maintaining 2 min.