Download Plants and diseases

作物病害
農業概論
陳昭瑩
• Estimated annual crop losses worldwide
– 31-42%
– Lower in the more developed countries
– Higher in the developing countries
• Average of total losses, 36.5%
– 14.1% caused by diseases ($220 billion)
• Should be added 6-12% losses of crops after harvest
• Not yet include losses caused by environmental factors
– Freezes, droughts, air pollutants, nutrient deficiencies, and toxicities
– 10.2% caused by insects
– 12.2% caused by weeds
Concept of disease in plants
• Disease in plants can be defined as:
– The series of invisible and visible responses of plant cells and
tissues to a pathogenic microorganism or environmental factor
that result in adverse changes in the form, function, or integrity
of the plant and may lead to partial impairment or death of
plant parts or of the entire plant.
– In some disease, hyperplasia or hypertrophy occur to produce
abnormal amorphous overgrowths (tumors) or abnormal organs.
• Types of plant diseases
– leaf spot, blight, canker, damping-off, dieback, mosaic, rot,
scab, shot hole, vascular wilt, downy mildew, powdery mildew,
rust, smut, gray mold, anthracnose, chlorosis, stunting, blast,
gall
Schematic diagram of the shapes and sizes of certain plant pathogens in relation to a plant
cell.
Infectious, or biotic, plant diseases
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Diseases caused by fungi
Diseases caused by prokaryotes (bacteria and phytoplasma)
Diseases caused by parasitic higher plants and algae
Diseases caused by viruses and viroids
Diseases caused by nematodes
Diseases caused by protists
Pests: Living things that affect humans, animals, or plants adversely
Methods of penetration and invasion by fungi
Methods of penetration and invasion by bacteria
Mechanical inoculation and early stages in the systemic distribution of viruses in plants
penetration and invasion by nematodes
Means of dissemination of fungi and bacteria
Forms and locations of survival of fungi and bacteria between crops
Noninfectious, or abiotic, plant
diseases
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too low or too high a temperature • Other factors may
cause
plant
disorder
lack or excess of soil moisture
– Chemical agents
lack or excess of light
– Wind
lack of oxygen
– Mechanical injury
– Ice storm
air pollution
– Electric storm
nutrient deficiencies
mineral toxicities
soil acidity or alkalinity (pH)
植物病害防治方法
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法規防治
耕作防治、栽培管理
生物防治
物理防治
化學防治
病蟲害綜合防治、作物綜合管理
(Integrated pest management, IPM)