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 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 too low or too high a temperature lack or excess of soil moisture lack or excess of light lack of oxygen air pollution nutrient deficiencies mineral toxicities soil acidity or alkalinity (pH) Other factors may cause plant disorder –Chemical agents –Wind –Mechanical injury –Ice storm –Electric storm

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) 植物病害防治方法