农药使用不当,常易引起作物出现不正常反应,造成减产和品质下降,这就是药害。产生药害的原因,主要有三个方面:一是用错了农药;二是使用了变质或含有害杂质的农药;三是没有掌握正确的施药技术。1.几种常见药害症状(1)斑点。主要发生在作物叶片上,有时也发生在茎、枝或果实上。常 Improper use of pesticides, often lead to crop abnormal reaction, resulting in reduced production and quality decline, this is the injury. There are three main causes of injury, one is the use of wrong pesticides, the other is the use of detergents or pesticides that contain harmful impurities, and the third is the failure to know the correct application of pesticides. 1. Several common symptoms of injury (1) spots. Occurs mainly in crop leaves, sometimes also occur in stems, branches or fruits. often