病毒病又称孤丁病、抽疯。该病发生面积广,为害严重,是白菜三大病害之一。发病后叶片变形,向一边弯曲、皱缩,呈浓绿色或浅绿色相间的花叶;或叶片产生很多黑褐色小点或园形坏死斑:病株矮小,严重的缩成一团,不包心。此病在播种前后及苗期高温、干旱,有利于有翅蚜的繁殖和传毒,往往发病较重:播种过早,苗期缺水以及窝风地块均易发病;幼苗六叶期间最易感染得病,发病越早,受害越重。因此,根据该病的发病条件,结合我地的防治经验,必须抓好以下几个方面的防治: Virus disease, also known as solitary disease, cramps. The disease occurred in a wide area, serious damage, is one of the three major diseases cabbage. After the onset of leaf deformation, bending to the side, shrinkage, was dark green or white mosaic flowers; or leaves a lot of brown spots or park-shaped necrosis spots: diseased plants short, serious shrink into a group, not wrapped . The disease before and after sowing and seedling heat, drought, is conducive to the breeding and transmission of winged aphids, often heavier: early sowing, seedling water and nest litter are susceptible to disease; seedling six leaf period Easily infected with the disease, the earlier the onset, the more victims. Therefore, according to the incidence of the disease, combined with my experience in prevention and treatment, we must do a good job in the following areas: