农药的混合使用及要求果树和农作物经常遭受多种病虫危害，有时几种病虫同时发生。如果分别用药常因劳力、药械有困难，时间不允许而延误时机，造成损失。为此，就要根据病虫发生的主次，一药多治的原则，配合一定比例，采用混用兼治方法，一次消灭所有或大部分病虫害。农... Mixed use of pesticides and requirements Fruit trees and crops often suffer from a variety of pest damage, and sometimes several diseases and pests occur simultaneously. If the drug is often due to labor, drug handling difficulties, time is not allowed to delay the opportunity, resulting in losses. Therefore, it is necessary to eradicate all or most of the pests and diseases at the same time according to the principle of occurrence and elimination of pests and diseases, the principle of treating multiple diseases with one drug, and a certain proportion with the method of mixing both cure and treatment. Farm ...