柑树黄化的原因很多。其中因肥伤、虫害、线虫和病菌等引起的黄化症状,与柑桔黄龙病的症状相似。由于其他许多原因引起黄化衰退的病弱树在中后期所呈现的花叶、小叶、落叶、梢枯、根腐和生长停顿等一般衰退症状,与黄龙病的中后期症状有时亦难于区别。这种黄化的情况在山地柑树显得更为复杂,往往难于鉴别,甚或引起错误的诊断。过去,在学术上曾对黄龙病的病原病毒问题,防治和检 Orange trees yellow for many reasons. Among them, yellowing symptoms caused by fatal injuries, insect pests, nematodes and germs are similar to the symptoms of citrus Huanglongbing. Due to many other reasons, emaciated trees which cause edema caused by yellowing are generally difficult to be distinguished from the symptoms of mid-late stage of Huanglong’s disease sometimes in the general recession symptoms such as mosaic, leaflet, deciduous leaf, withered root, root rot and growth in the late period. This yellowing situation is more complicated in the mountain citrus trees, often difficult to identify, or even cause wrong diagnosis. In the past, in the academic history of the Huanglong disease pathogenic virus, prevention and seizure