水田毒害是指土壤中还原性有毒物质所引起的生理性病害可分为以下几种: 1、二价铁毒害:致害的有毒物质主要是二价铁。主要症状是下部叶片自叶尖开始出现棕色或褐色斑点,渐向叶基发展,直至全叶变褐。近根端处多须状分枝,根际土壤青灰色。其主要原因是二价铁阻碍了营养元素的吸水稻生育后期病害以穗茎瘟、纹枯病、稻曲病、粒黑粉病为主,尤以粒黑粉病发生较为普遍。据调查,我省水稻粒黑粉病一般株发病率在20—30%,粒发病率5—10%。影响子粒成熟,空秕粒增加,造成减产。在防治上应采取下措施: 1、用40%灭病威胶悬剂,每亩 Paddy field poisoning refers to the reduction of soil toxic substances caused by physiological diseases can be divided into the following categories: 1, ferrous iron poisoning: the poisoning of the material is mainly ferrous iron. The main symptom is that the lower leaves begin to show brown or brown spots from the tip of the leaves, progressing toward the leaf base until the whole leaf becomes brownish. Near the root end to be more like branches, rhizosphere soil blue gray. The main reason is that ferrous iron hinders the absorption of nutrients at the late stage of rice growth disease head blight, sheath blight, rice false smut, grain smut disease, especially in the occurrence of powdery mildew is more common. According to the survey, the general incidence of rice grain powdery mildew in our province is 20-30%, grain incidence 5-10%. Affect the maturity of grain, empty grains increase, resulting in reduced production. In the prevention and control should take the following measures: 1, with 40% off Wei Wei suspension, per acre