由于农药使用不当而造成药害的现象时有发生,正确识别药害与病害及生理性病害在农业生产中有着重要的作用。作物药害的症状:1、斑点主要发生在叶片、茎杆或果实表皮上。常见的有褐斑、黄斑、网斑等。药斑分布没有规律性,整块地有轻有重。病斑发生则较普遍,植株出现部位一致。2、黄化黄化可发生在植株茎叶部位,以叶片黄化居多,引起黄化的主要原因是农药阻碍了叶绿素的正常光合作用,轻度发生表现叶片发黄,重度发生全株发黄。营养元素缺乏引起的黄化常与土壤肥力有关,全地块黄苗表现一致。病毒引起的黄叶常有碎绿状表现,在田间病株与健株混生。3.畸形由药害引起的畸形可发生于作物茎叶和根部,常言卷叶、丛生、肿根、畸形穗、畸形果等。药害畸形与病毒病害畸形不同,前者发生普遍,植株上表现局部症状,后者表现系统性症状,往往零星发生,常在叶片上混有碎绿明脉、皱叶 Due to improper use of pesticides caused by the phenomenon of phytotoxicity from time to time, the correct identification of phytosanitary and disease and physiological diseases in agricultural production has an important role. Symptoms of crop phytotoxicity: 1, the spots occur mainly in the leaves, stems or fruit epidermis. Common brown spots, macula, mesh spots and so on. There is no regularity of the distribution of drug spots, there is a whole piece of light and heavy. Lesions are more common, plant parts appear the same. 2, yellowing can occur in the plant stems and leaves parts, the majority of the leaves yellowing, the main cause of yellowing is the pesticide hindered the normal photosynthesis of chlorophyll, leaves showed mild yellowish, severe yellowing of the whole plant . Lack of nutrients caused by yellowing often associated with soil fertility, the same performance throughout the block yellow seedlings. Yellow leaves caused by the virus often broken green performance, in the field of diseased plants and strains mixed. 3 deformities caused by the deformity can occur in crop stems and leaves, roots, often rolling, tufts, swollen roots, deformed spikes, deformed fruit and so on. Deformity and virus disease deformity is different, the former common occurrence of local symptoms on the performance of plants, the latter manifestations of systemic symptoms, often sporadic occurrence, often in the leaves mixed with broken green Mingmai, foliage