玉米弯孢菌叶斑病研究

CURVULARIA LEAF SPOT OF MAIZE:PATHOGENS AND VARIETAL RESISTANCE

玉米弯孢菌叶斑病是近年来北京、河北、河南、山东、辽宁、吉林等北方玉米产区新发生的重要病害之一。其主要病原菌为弯孢菌Ｃｕｒｖｕｌａｒｉａｌｕｎａｔａ（Ｗａｌｋ）Ｂｏｅｄ．，局部地区同时存在Ｃｕｒｖｕｌａｒｉａｉｎａｅｑｕａｌｉｓ（Ｓｈｅａｒ）Ｂｏｅｄ．，但以前者为主要。弯孢菌Ｃ．ｌｕｎａｔａ生长适温为２８～３２℃，对ｐＨ适应范围广。玉米叶片浸汁可以促进分生孢子的萌发和芽管的生长。干燥条件下，病原菌在植株病残体上可以安全越冬，成为次年田间的初侵染源。病菌分生孢子形态为多态型，但单孢分离后代仍保持孢子的多态型，致病性无变化。病菌不同菌株间致病力有差异，强致病力菌株存在于北京及周边地区。人工接种鉴定１２０份玉米品种（组合）、自交系，材料间存在明显的抗性差异，抗性较好材料有农大１０８、中玉５号、高油１１５等及自交系ＣＮ９５、ＣＮ１６５等。品种抗病性随植株生长而递减。苗期抗性较好，１３叶期极为感病，因此弯孢菌叶斑病属于成株期病害。

A new leaf spot disease of maize,mainly caused by Curvularia lunata (Walk) Boed. and C.inaequalis (Shear) Boed.,is becoming prevalent in north China.The optimum temperature for growth of C.lunata is 28～32℃,and it grows well at 4～12 pH values,maize leaf extract accelerated germination of conidia and growth of germ tube.At dry condition, C.lunata successfully overwintered in diseased leaves and become primary infection sources in fields.The conidia of C.lunata are different in shape,and progenies isolated by using single spore technique are same on pathogenicity. Some isolates of C.lunata ,especially isolated from Beijing are high in pathogenicity.Under artificial inoculation condition,120 maize accessions are evaluated for resistance to Curvularia leaf spot,of which,49 accessions were resistant types (HR,R and MR),and Nongda 108,Zhongyu 5,Gaoyou 115,CN95 and CN165 are high resistant.The resistance was high in seedling stage and low in adult plant.