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。 The results showed that there was a significant linear correlation between yield loss and disease grade and disease index. Each level increases by 1 level, yield loss increases by an average of 8.25%. For each 10% increase in the disease index, the yield loss increased by an average of 4,14%. In the composition of yield loss, the decline of 1000-grain weight dominates, accounting for 66.6%; the reduction of grains per spike is second, accounting for 33.4%. According to the mathematical model of disease index and yield loss rate, the economic permissible level of harm in high, medium and low yielding fields was estimated, and the control index was determined. After field verification, you can use this to guide the prevention and treatment of the disease.