玉米弯孢菌叶斑病重要流行环节的初步研究——孢子萌发、侵染、潜育、显症

lmportant Epidemic Links of Corn Leaf Disease Caused by Curvularia Lunate (Walker)Boedijn --germination,penetration of conidium, latent period, symptom of disease

弯孢菌孢子在清水中或可直接萌发 ,或不能直接萌发 ,玉米花粉粒及叶面渗出物质对弯孢菌孢子萌发有明显促进作用。萌发孢子遇超过 30s的干燥即丧失侵染能力。弯孢菌在 15℃至 35℃都可对玉米形成侵染 ,以2 5℃左右为最适侵染温度。叶面结水时间需超过 7h才能形成侵染。在田间自然条件下 ,弯孢菌叶斑病的潜育期为 3～ 4d ,持续显症时间为 4～ 5d ,温度是影响潜育期的重要因子 ,病斑扩展的最大直径为 1～ 2mm。

The germination of the conidium of Curvularia lunata could be increased by corn polien and leaf excreta. Germinating conidium could loss the ability of penetration into corn leaves when they were dried over 30s,The infection of the fungus occured at temperature between 15℃ and 35℃ and the most suitable temperature is 25℃.The fungus could infect corn only when the leaves were covered with water over 7 hours, In natural conditions, the symptom of the disease appeared 3 to 4 days after penetration, and the symptom could be kept for 4～5 d. Temperature is an important effective factor for latent period of the disease.In the suitable conditions,a single lesion could expand to the largest diameter about 1～2 mm.