一 病狀和病原方面的研究概况 黄龙病是目前广东、福建柑桔产区的严重病害。发病第一年,受害植株部分大枝或全株新梢或部分新梢的叶片从叶脉附近开始黄化,逐漸扩展到全叶,叶脉肿突,有时开裂。病枝上抽生的新梢变短,叶片变小,部 A study of pathology and pathogens Overview Huanglong disease is currently a serious disease in Guangdong, Fujian citrus producing areas. In the first year of the disease, the leaves of some branches or whole shoots or part of the shoots of affected plants began to yellow from the vicinity of the veins and gradually expanded to the entire leaves. The veins of the branches and veins sometimes cracked. Stems shoot new shoots shorter, smaller leaves, Ministry