Plant Diseases


  1. Description: Not-living! Protein sheath around a nucleic acid core.
  2. Classified: by nucleic acids (DNA, RNA, ssDNA, etc).
  3. Symptoms: Varies, but some nearly symptomless.
  4. Vectors: Spread by insects, pollen (to seeds), humans and their tools.
  5. Examples: Tobacco mosaic virus (TMV)
  6. Treatment: Difficult to treat since infected cells are host cells, so sanitation and planting resistant cultivars.
  7. Good resource: DPVweb


  1. Description: Very small single cells with no organelles, DNA in circles.
  2. Classified: by shape with rod (bacilli) most common, also spherical (cocci), spiral (spirilla).
  3. Symptoms: Varies - specific to plant
  4. Vectors: Water splashes, wounds
  5. Examples: Fire blight, crown gall, potato scab, wilts, soft rots.
  6. Treatment: Sanitation and cultural (dry foliage & stems), avoid excess N, plant resistant cultivars.
  7. Most bacteria are very helpful !!


  1. Description: Absorptive eukaryotic cells, reproduce asexually and with spores.
  2. Classified: Seven (or so) classifications
  3. Symptoms: Varies: wilting, leaf spots, scab.
  4. Vectors: Soils and water, some insects, alternate hosts
  5. Examples: damping-off, Dutch elm disease, rusts and smuts, Botrytis, Phytophthora
  6. Treatment: Sanitation and planting resistant cultivars.