近年来,据我们在黄河故道苹果产区的一些苹果园抽样调查发现,苹果小叶病发生很普遍,并有不断加重的趋势。大部分苹果园发病株率在20％左右,少数管理粗放的果园发病株率高达80％。该病直接影响叶片的正常生长,使叶面积减小,光合作用降低,造成营养生长不良;从而影响正常结果,使花芽形成置减少,座果率低,果实发育不正常。发病严重的植株完全丧失结果能力,甚 In recent years, according to our sample survey on some apple orchards in the apple producing areas in the old course of the Yellow River, it has been found that the occurrence of apple leaf disease is widespread and has been on the increase. Most of the apple orchard incidence rate of about 20%, a small number of extensive management of orchards in the incidence of up to 80%. The disease directly affects the normal growth of the leaves, reducing the leaf area and decreasing the photosynthesis resulting in poor vegetative growth; thereby affecting the normal results, reducing the flower bud formation, low fruit set rate and abnormal fruit development. The severely diseased plants have the ability to lose results completely