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苹果黄叶病又称黄化病或失绿病。近年来我区苹果发生这种病比较普遍,轻者树势迅速衰弱,结果不良;严重时可使整株死亡。据1973年在灵武园艺场原自流灌区调查的864株苹果中,发病的达366株,发病率42.4%。其中:Ⅰ级病株(黄叶26%以下)有139株,Ⅱ级病株(黄叶26～50%)有107株,Ⅲ级病株(黄叶75%以上)有78株,Ⅳ级病株(全株黄叶并有干梢)有42株,病情指数达21.8%。
Apple yellow leaf disease, also known as yellow disease or chlorosis. In recent years, the occurrence of this disease is more common in our district of apple, the light of the rapid decline of the tree vigor, the result is not good; in severe cases can make the whole plant died. According to the survey of 864 apples collected from the original self-irrigation irrigation area of Lingwu Horticultural Field in 1973, 366 strains were found and the incidence rate was 42.4%. Among them, there were 139 strains of grade Ⅰ (below 26% of yellow leaves), 107 of grade Ⅱ (26 to 50% of yellow leaves), 78 of grade Ⅲ (more than 75% of yellow leaves) Strain (whole plant yellow leaves and dry tip) has 42 strains, the disease index of 21.8%.