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一、缺乏营养无素引起的叶片黄化。 (一)缺氮初期叶面出现不规则黄色斑块,后期全叶变黄,叶片少、薄,易早落。可根际增施氮肥或叶面喷施0.5％尿素溶液2～3次防治。 (二)缺钾初期老叶叶尖、叶缘黄化,后扩展至全叶,叶片卷缩为畸形。可根施钾肥或在夏季叶面喷施0.4％硝酸钾2～3次防治。 (三)缺钙最初新生叶片叶尖黄化,后发展到叶缘中上部,叶片比正常叶片狭长,易早落。可在新叶期喷施0.3％硝酸钙数次或土壤增施石灰防治。
First, the lack of nutrient-induced leaf yellowing. (A) Irregular yellow patches appear on the foliage at the early stage of nitrogen deficiency, the late leaves turn yellow, leaves less, thin and easy to fall early. Rhizosphere can increase nitrogen fertilizer or foliar spraying 0.5% urea solution 2 to 3 times control. (B) the initial potassium deficiency leaf tip, leaf margin yellow, then extended to the whole leaf, leaf curl into deformity. Potassium fertilizer can be applied or in the summer foliar spraying 0.4% potassium nitrate 2 to 3 times control. (C) Calcium Initial leaf of newborn leaves yellow, after the development to the leaf margin in the upper part of the leaves than the normal long, easy to early fall. In the new leaf stage spraying 0.3% calcium nitrate or lime control soil.