一、类菌原体的发现黄化病是常见的植物病害,它是一种整株性病害。其主要病症为:叶片黄化、植株矮化、侧枝丛生、花部变叶等。随着症状加剧,使植株衰弱,最后可致死。水稻黄萎病、玉米矮化病、马铃薯丛枝病、桑树萎缩病、泡桐丛枝病、梨树衰退病、柑桔黄龙病、茄子小叶病等植物病害都属黄化病。植物黄化病造成严重损失,如我国泡桐丛枝病严重病区发病率可达80%以上,一般为30～50%,严重影响林木生长。1959～1962年,仅在美国加利福尼亚州,就因梨树衰退病而导致110 First, the discovery of mycoplasmas Yellow disease is a common plant disease, it is a whole plant disease. The main symptoms are: yellow leaves, plant dwarf, collateral tufts, flowers and other leaves. As the symptoms worsen, the plants become weaker and eventually die. Plant diseases such as Verticillium dahliae, maize dwarf disease, potato broom, mulberry atrophy, Paulownia witches broom, pear decline, citrus Huanglongbing, eggplant leafhopper are yellow disease. Plant yellow disease caused serious losses, such as our country Paulownia witches broom disease incidence of up to 80%, generally 30 to 50%, seriously affecting the growth of trees. From 1959 to 1962, only in California, USA, it was caused by the decline of pear trees