(2) Physiological races( biotypes):生理小种 (型) The pathogens differentiated from the same disease. with the same morphology, but different virulence to different varieties of the host plants. Physiological races are: Variety-specific( Cultivar- specific)):品种专化性 Differentiations of highly parasitic pathogens高度专性 寄生物具有的分化 Genetically controlled in pathogenecity Frequently changing in composition(with prevalent races 优势小种（2） Physiological races （biotypes)：生理小种 （型） The pathogens differentiated from the same disease, with the same morphology, but different virulence to different varieties of the host plants. Physiological races are: • Variety-specific (Cultivar-specific)：品种专化性 • Differentiations of highly parasitic pathogens 高度专性 寄生物具有的分化 • Genetically controlled in pathogenecity • Frequently changing in composition (with prevalent races 优势小种)