玉米弯孢菌叶斑病田间发生动态研究

【目的】对玉米弯孢菌叶斑病田间发生动态进行研究，为生产上防治该病提供一定的理论依据。【方法】采用田间调查和人工接种的方法，调查玉米弯孢菌叶斑病在田间的病株发病率、病叶发病率和病情指数的变化规律，研究该病在田间的发病规律；通过测定不同生育期玉米叶片上病斑的产孢量和病斑面积，研究玉米不同生育期的抗病性。【结果】在四川雅安生态条件下，玉米弯孢菌叶斑病的始发期为5月中旬，从5月下旬至7月中旬病情指数迅速增长；玉米孕穗期叶片病斑面积和产孢量最大，大喇叭口期次之，苗期最小；玉米下部叶片上病斑的产孢量和病斑面积大于上部叶片病斑的产孢量和病斑面积。【结论】在四川雅安生态条件下，玉米弯孢菌叶斑病的始发期为5月中旬；玉米苗期最抗病，孕穗期最感病；下部叶片较感病，上部叶片较抗病。

Dynamics of maize Curvularia leaf spot occurrence

Objective] The experiment was undertaken to investigate the dynamics of maize Curvularia leaf spot to provide the theoretical basis for development of its control measures for sustaining maize production. Method] Incidence of infected plants and disease index of maize Curvularia leaf spot were investigated using artificial inoculation and field investigation methods. Occurrence regularity and disease resistance at different growth stages were also worked out by determining size of lesions and sporulation quantity. Result] The first incidence of maize Curvularia leaf spot was observed in mid May, followed by a rapid increase in disease index from late May to mid July in Ya＇an during 2004. The incidence was found highest at hooting stage, moderate at full-grown stage, and least at seedling stage. Further, the size of lesions and sporulation quantity were found higher in lower leaves compared to those on the tops. Conclusion] The first period of maize Curvularia leaf spot was in mid May in Ya＇ an, Sichuan, maize seedling had the best and worst resistance in seedling stage and booting stage, respectively. The upper leaves of maize were more resistant to maize Curvularia leaf spot than the bottom leaves.