(4) Breeding for resistant varieties is the Safest Most efficient Most economical measure to control plant diseases and pests
(4) Breeding for resistant varieties is the: Safest Most efficient Most economical measure to control plant diseases and pests
82 The Pathogenecity of Pathogens and the Resist- ance of plants病原物的致病性和植物的抗 病性 1. The variation of Pathogenecity in Pathogens (1) Pathogenecity致病性 Ⅴ irulence毒性十 Agressiveness浸袭力 Specific pathogenecit!y专化致病性(寄生性病原物) Non- specific pathogenecity非专化致病性(腐生物)
§2 The Pathogenecity of Pathogens and the Resist-ance of Plants 病原物的致病性和植物的抗 病性 1. The Variation of Pathogenecity in Pathogens （1）Pathogenecity 致病性 = Virulence 毒性 ＋ Agressiveness 浸袭力 • Specific pathogenecity 专化致病性（寄生性病原物） • Non-specific pathogenecity 非专化致病性（腐生物）
(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)
2 The resistance of host plants植物的抗病性 (1)Phenotypic Types of resistance Escape Tolerance Resistance Immune 免疫性 Hypersensitive过敏性( Necrotic spot坏死斑点) - Susceptible感病性 Mechanism of resistance Resistance to penetration Resistance to expanding
2 The Resistance of Host Plants 植物的抗病性 (1) Phenotypic Types of resistance • Escape •Tolerance • Resistance - Immune 免疫性 - Hypersensitive 过敏性（ Necrotic spot 坏死斑点） - Susceptible 感病性 Mechanism of resistance: • Resistance to penetration • Resistance to expanding
(2) Genotypic types of resistance A. Vertical resistance垂直抗病性 a variety is particularly resistant to one or some specific races of pathogens while it is highly susceptible to other races. Race specific resistance: single genes, oligo-genes Small environmental Influence: Non-durable resistance Incidence Race a e
(2) Genotypic types of Resistance A. Vertical Resistance 垂直抗病性 A variety is particularly resistant to one or some specific races of pathogens while it is highly susceptible to other races. Race specific resistance: single genes, oligo-genes Small environmental Influence; Non-durable resistance Race a b c d e f Incidence %