我国北方苹果区由于防治桃小食心虫和卷叶虫等,长时期地使用杀虫范围广的有机合成杀虫剂而引起了叶螨类的普遍发生。近几年来,有些地方施用肥料质量下降,或氮肥偏多,又使苹果白粉病逐渐蔓延起来。这两种病 Due to the prevention and control of peach moth and leaf roller insects in North China, long-term use of pesticides with a wide range of pesticides caused the spider mites common. In recent years, the quality of fertilizers applied in some places has decreased or nitrogenous fertilizer has been on the increase. In turn, apple powdery mildew has gradually spread. These two diseases