近年来,我县部分苹果园有黄叶病的发生,个别果园比较严重.主要病状从叶幼开始,一般是部分枝条嫩叶脉间失绿变为黄色,叶脉仍保持绿色.重者,大部分叶片变黄,叶脉迹退绿,全叶呈黄白色,叶小而薄,叶片切缘发生干枯褐色斑块,以后全叶干枯脱落.发病后新梢生长迟缓,节间短,有时枯顶.重病树年年发病,果实小、绿而硬,树势衰弱甚至死亡. In recent years, part of apple orchards in our county have the occurrence of yellow leaf disease, and individual orchards are more serious. The main symptoms begin from young leaves, usually the part of green leaves turn green, while the veins remain green. Leaves turn yellow, leaf veins back to green, the whole leaf was yellow-white, small and thin leaves, leaf edge dry brown patches, after the whole leaf dry off. After onset of shoot growth retardation, internodes short, and sometimes dry top. Severe disease occurs year by year, the fruit is small, green and hard, trees weak or even death.