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柑桔黄梢(黄龙)病的研究几年来的进展不快,但仍取得了如下一些成果。柑桔树受侵染后,一般在夏、秋梢老熟期开始发病,但最近发现,亦可在春梢老熟后开始表现病状,其特征为新叶老熟后转为灰绿色。冬季发病的初期病状有时表现为老熟后的新叶中肋黄化。病树叶的澄清汁液与 KOH 或与 NaOH 混和,每有转变为橙缸色的反应,但不一致。曾经被认为可能是黄梢病原的真菌“Deuterophoma sp”已被证明与本病的发生无关。初步试验结果表示柑桔褐蚜可能是一种传染媒介。种子带病的可能性不能排除,有待进一步探讨。病树的根残留土中显然不起传病作用。黄梢病毒在病株体内似以相等的速度同时向上下运转。用13种柑桔类作为砧木,对蕉柑的抗病性皆不起显著的增强作用。不同树龄的植株表现显然不同的抗病性。苗木和老年树比较抗病,幼年树则容易发病。环境因素对植株的发病不起决定性的影响,因而采取栽培措施不能抑制发病,更不能收到治疗效果。挖除病株和喷药除虫则可在一定程度上起抑制蔓延的作用。初步试验表示,用热水或湿热空气处理病树芽条可以消除带病。
Research on citrus yellow shoots (yellow dragons) has progressed unpleasantly in recent years, but some achievements have still been made. Citrus trees are infected, usually in the summer and autumn tip of the mature period began to attack, but recently found, but also in spring shoots began to show signs of aging, which is characterized by a new leaf turned green-gray. The initial onset of winter disease is sometimes manifested as ribification of new leaves after ripening. The clarified juice of diseased leaves is mixed with KOH or with NaOH, each changing to an orange-cylinder reaction, but inconsistent. The fungus “Deuterophoma sp”, once thought to be the pathogen of the yellow tip, has been shown to be unrelated to the onset of this disease. Preliminary results indicate that the citrus black aphid may be a vector. The possibility of seed disease can not be ruled out, pending further study. The root of the diseased tree leaves apparently can not play the role of disease transmission. The tip of the virus in the diseased plants in the body at the same speed at the same time up and down operation. With 13 kinds of citrus as rootstock, the resistance of banana can not afford any significant enhancement. Plants of different ages show distinctly different disease resistance. Seedlings and old trees are more resistant to disease, juvenile trees are prone to disease. Environmental factors on the incidence of plants can not play a decisive role, so take measures to prevent the incidence of cultivation, but can not receive the treatment effect. Digging diseased strains and spraying insecticide can to a certain extent, play a role in inhibiting the spread. Preliminary tests show that treatment of sick tree buds with hot or humid air can eliminate disease.