一、苗期病害的症状与类型 1、真菌性苗病。主要症状表现为玉米幼苗3—5叶期,叶片出现褐色斑,根系变褐缢缩,胚根褐色腐烂。后期轻者发展成黄枯型,能恢复,但多形成三类苗,重者褐色枯死。 2、病毒性苗病。被害玉米病叶沿叶脉褪色失绿,呈线纹或条点型的斑驳花叶状。植株不同程度矮化,重者比正常植株矮化 50%以 First, the symptoms and types of seedling disease 1, fungal disease. The main symptoms of corn seedlings 3-5 leaf stage, the leaves appear brown spots, brown roots shrinkage, radicle brown decay. The late development of light yellow scum type, can recover, but the formation of three types of seedlings, severe brown dead. 2, viral disease. The diseased leaves of maize were faded greenish along the veins and showed mottled mosaic-like lines or lines. Dwarf plants to varying degrees, severe dwarf plants than the normal 50%