- Description: Not-living! Protein sheath around a nucleic acid core.
- Classified: by nucleic acids (DNA, RNA, ssDNA, etc).
- Symptoms: Varies, but some nearly symptomless.
- Vectors: Spread by insects, pollen (to seeds), humans and their tools.
- Examples: Tobacco mosaic virus (TMV)
- Treatment: Difficult to treat since infected cells are host cells, so sanitation and planting resistant cultivars.
- Good resource: DPVweb
- Description: Very small single cells with no organelles, DNA in circles.
- Classified: by shape with rod (bacilli) most common, also spherical (cocci), spiral (spirilla).
- Symptoms: Varies - specific to plant
- Vectors: Water splashes, wounds
- Examples: Fire blight, crown gall, potato scab, wilts, soft rots.
- Treatment: Sanitation and cultural (dry foliage & stems), avoid excess N, plant resistant cultivars.
- Most bacteria are very helpful !!
- Description: Absorptive eukaryotic cells, reproduce asexually and with spores.
- Classified: Seven (or so) classifications
- Symptoms: Varies: wilting, leaf spots, scab.
- Vectors: Soils and water, some insects, alternate hosts
- Examples: damping-off, Dutch elm disease, rusts and smuts, Botrytis, Phytophthora
- Treatment: Sanitation and planting resistant cultivars.