Plant pathology is also known as phytopathology. It is the scientific study of diseases in plants caused by pathogens (infectious organisms) and physiological factors. Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes, and parasitic plants. Not included are ectoparasites like insects, mites, vertebrates, or other pests that affect plant health by eating plant tissues. Plant pathology also involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology, plant disease resistance, how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases.
Plant diseases cause major economic losses for farmers worldwide. Across large regions and many crop species, it is estimated that diseases typically reduce plant yields by 10% every year in more developed settings, but yield loss to diseases often exceeds 20% in less developed settings. The Food and Agriculture Organization estimates that pests and diseases are responsible for about 25% of crop loss. To solve this, new methods are needed to detect diseases and pests early, such as novel sensors that detect plant odors and spectroscopy and biophotonics that can diagnose plant health and metabolism.
- Fungi: The fungi reproduce both sexually and asexually via the production of spores and other structures. Spores may be spread long distances by air or water, or they may be soil-borne. Many soil-inhabiting fungi are capable of living saprotrophically, carrying out the part of their life cycle in the soil. These are facultative saprotrophs. Fungal diseases may be controlled through the use of fungicides and other agriculture practices. However, new races of fungi often evolve that are resistant to various fungicides. Biotrophic fungal pathogens colonize living plant tissue and obtain nutrients from living host cells. Necrotrophic fungal pathogens infect and kill host tissue and extract nutrients from the dead host cells.
Significant Fungal Plant Pathogens Include.
- Fusarium spp.
- Thielaviopsis spp.
- Verticillium spp.
- Magnaporthe grisea (rice blast)
- Sclerotinia sclerotiorum (cottony rot)
- Ustilago spp. smut of barley
- Rhizoctonia spp.
- Phakospora pachyrhizi (soybean rust)
- Puccinia spp.
- Armillaria spp.