玉米弯孢菌叶斑病危害损失及防治指标研究

对河南玉米弯孢菌叶斑病危害损失测定结果表明，产量损失与病级、病情指数之间均存在着极显著的直线相关。病级每提高１级，产量损失平均增加８.２５％。病情指数每增加１０％，产量损失平均增加４.１４％。在产量损失构成中，千粒重下降处主导地位，约占６６.６％；穗粒数减少次之，约占３３.４％。根据病情指数与产量损失率的数学模型，分高、中、低产田对经济允许危害水平进行了估算，并确定了防治指标。经田间验证，可以用此指导该病的防治。

Damage and control index of corn leaf spot infected by Curvularia lunata in Henan Province.

The damage determination of corn leaf spot infected by Curvularia lunata in Henan Province suggested that there existed significant correlation between yield loss and disease rank and disease index. The yield loss rate increased by 8.25% with disease raised every one rank. The yield loss rate increased by 4.14% with every 10% addition of disease index. The thousand grain weight reduction was the main reason of yield loss and fertile grain reduction took second place. The control index was determined, according to the mathematical model of disease index and yield loss rate and based on the estimation of EIL respectively for the fields of high, middle and low yield. The field validation showed that the control index can be used for controlling the disease.