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 booting 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.