玉米大斑病是由长蠕孢属的一种真菌侵染所引起的叶部病害,除为害玉米外,还加害高粱.玉米产区每年都有不同程度的发生.一九六五年以来,此病为害逐年加重,六六、六七、七一、七三年曾在我区洛南、商县、商南等地严重流行,一般减产15—30%,重病田减产50%以上,掌握该病的流行规律,及时有效地控制为害,已成为当前玉米生产上急待解决的问题. Maize leaf spot is caused by a fungus infection of Helicobacter sp., Which not only harms maize, but also damages sorghum. The maize producing area varies from year to year. Since 1965, The disease is worsening year by year. In June, June, July, July and July and 1973, it was endemic in Luonan, Shangxian and Shangnan districts of our region, with a general decrease of 15-30% and a reduction of more than 50% in seriously ill fields. The prevalence of the disease, the timely and effective control of damage, has become an urgent problem in the current corn production.