玉米大、小斑病主要危害叶片,受害后出现大小不同的病斑,叶面过早干枯,甚至死亡,一般减产15—20%,重者可减产50%以上。防治好玉米大、小斑病,是夺取玉米高产优质的关键。现将该病的发生及防治措施介绍如下:一、为害症状:大斑病明显特征是在叶片上形成梭形大斑,一般长5—10厘米,宽1.2——1.5厘米;病斑黄褐色或青灰色,中部颜色较 Large and small spot disease of maize leaves are the main hazards to the leaves. After the victimization, spots of different sizes appear, the leaves are prematurely dried up and even die. Generally, the output is reduced by 15-20% and the weight can be reduced by 50% or more. Prevention and treatment of large corn, small spot disease, is the key to the high yield and quality of corn. Now the occurrence of the disease and prevention and treatment measures are described below: First, the symptoms of damage: Great spotted disease is characterized by the formation of fusiform large spot on the leaves, usually 5-10 cm wide and 1.2--1.5 cm wide; spot yellowish brown Or blue-gray, the central color more