症状　香蕉黄叶病初发时 ,植株下部老叶主脉两侧呈现斑驳形褪绿 ,后蔓延至全叶褪绿 ,并逐渐向上部叶片扩展 ,逐叶褪绿 ,变黄。根由初发病时的白色逐渐转变为淡黄色 ,外皮呈现木栓化 ,质脆易断 ,严重时根变黑 ,甚至腐烂。植株发病后生长缓慢 ,树势衰弱 ,抗病力下降 ,常常引发其? Symptoms In the first attack of banana yellow leaf disease, both sides of the main veins of the lower leaves of old plants showed mottled chlorotic, then spread to the whole leaf chlorotic, and gradually expanded to the upper leaves, chlorotic by leaf, yellowing. The root from the initial incidence of white gradually transformed into light yellow, cortex appearing cork, crisp and brittle, severe black, or even decay. After the onset of slow plant growth, tree weakness, decreased resistance to disease, often lead to it?