湖北宜昌县柑桔示范场的柑在每年 3～ 5月都出现异常落叶 ,在 5～ 1 0 d内老叶从叶尖开始向叶基失绿变黄 ,直至全叶 1 / 3～ 1 / 2 ,主脉变黑褐色失水皱缩 ,叶尖开始变褐焦枯脱落 ;或老叶片叶脉间出现不规则斑块状叶肉失绿变黄 ,而后出现黑褐色斑点脱落。严重时当年萌发新芽 Orange leaves in Yichang County, Hubei Province, showed abnormal deciduous leaves from March to May every year. The old leaves began to turn green from yellow leaves to yellow leaves until the whole leaves were from 1/3 to 1 / 2, the main veins dark brown water shrinkage, the tip began browning scorched off; or old leaf veins irregular plaques appear green turn yellow, and then dark brown spots off. Germination of germination in severe year