Biological characteristics of the pathogen causing gray leaf spot of loquat

GU Hui; CHEN Wei-xin; LIU Ai-yuan; FENG Shu-jie; QI Ying

Abstract：The effect of temperature, pH,light, carbon source, nitrogen source and moisture on the mycelial growth, sporula-tion and conidial germination of loquat gray leaf spot fungus [Pestalotiopsis eriobotryfolia (Guba) Chen et Chao]was primarily studied. For the mycelia growth ofP. eriobotrffolia ,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 lO,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, ammo-nium phosphate,or ammonium nitrate could inhibit the conidial germination. The lethal temperature for the spores was 50 ℃ maintaining 10 minutes or 55 ℃ maintaining 2 rain ,while the lethal temperature for the mycelium was 50 ℃ maintaining 15 min or 55 ℃ maintaining 2 min.