Spread gradient model of leaf spot disease (Curvularia lunata) in maize

According to the principles of plant disease epidemiology, the dynamics of spread of leaf spot disease in two successive years was studied by artificial inoculation, which causes the disease gradient of Curvularia lunata in maize in experi_ mental fields. The disease gradient model, which was established using the software for SPSS, shows that exponential model is the optimum one in Shenyang region. During the maize growing season of two months, the results show that x=9.606×EXP(-0.2829×d) is the optimum model for the maize cultivar's Yeddan 13, and x=7.154×EXP(-0.2351×d) for cultivar's Haishi 16. The furthest spread distance of the disease is about 28 m within two months of the growth season, and the velocity of spread of the disease between 0.4-0.5 m/d.