稻苗疫霉病(Phytophthora·sp)主要在早、中稻苗期发生。秧苗发病后,叶上产生褐色圆形或椭圆形斑点,环境条件适宜时迅速发展成灰绿色、水烫状不规则条斑,清晨或阴雨天气病斑上可产生白色稀绒状霉层,发病后期病斑呈褐色,边缘紫褐色,中间灰褐色。由于病斑扩大或愈合,病叶尖端或中、上部发生纵卷或折断,造成中、 Phytophthora sp (Phytophthora sp.) Mainly occurs in the seedling stage of early and middle rice. After the onset of seedling, the leaves produce brown round or oval spots, the rapid development of appropriate environmental conditions into a gray-green, water-like irregular streaks, early morning or rainy days spot can produce white thin layer of moldy, disease Late lesions were brown, brown purple edge, the middle of taupe. As the lesion enlarges or heal, the tip of the diseased leaves or in the upper part of the vertical roll or broken, resulting in,