一、病害的简易诊断与防治 (一)病害的病原及症状蔬菜病害的病原一般有下列几种:病原真菌、病原细菌、病毒、寄生线虫、寄生性种子植物、非传染性病害等病原。蔬菜发病后,发生一系列复杂的病变,这些病变表现称为症状。症状可分为两部分:寄主发病后表现的不正常状态,称为病状;病原生物在寄主上的特征性表现称为病症。在病害发生后,首先应根据病状判断出病害的种类,然后才能对病施药。寄生性种子植物本身就是特殊的症状结 First, the simple diagnosis and prevention of disease (A) the pathogen and symptoms of diseases The pathogen of vegetable diseases are generally the following: pathogenic fungi, pathogenic bacteria, viruses, parasitic nematodes, parasitic seed plants, non-infectious diseases and other pathogens. After the onset of vegetables, a series of complex lesions, the performance of these lesions known as symptoms. Symptoms can be divided into two parts: the host after the onset of abnormal performance, known as the disease; pathogenic organisms in the host of the characteristic performance is called the disease. After the disease occurs, we should first determine the type of disease according to the disease, and then apply the disease. Parasitic seed plants themselves are special symptoms