Latin name : Streptomyces spp.
Diagnostic characters for visual diagnosis
- Tuber infection starts with superficial brown lesions which develop into the regular striking netlike structure typical of netted scab
- These lesions may be localised, but may also cover almost the entire tuber surface.
- Netted scab affects all subterranean parts of potato plants. Brown lesions develop on stem bases, on stolons and on roots.
Notes on confirmatory diagnostics
- To confirm, several steps must be completed because some saprophytic strains might be isolated together with the pathogenic ones :
- Isolation of Streptomyces strains on water agar or on other semi selective medium,
- Selection of the pathogenic strains by testing their pathogenicity on susceptible varieties (for exemple Bintje or Désirée),
- Identification of the species associated with the lesions by sequencing the 16S rRNA gene or by using specific primers.
Specific references :
Bouchek-Mechiche et al (2000 b). PlantPathology, 49, 3-10
Bouchek-Mechiche et al (2006). IJSEM, 56, 2771-2776.
Loria et al (1997). PlantDisease, 81, 836-846.
Scholte K (2005). Netted scab in: PotatoDiseases, NIVAP, 83-84
Possible confusing symptoms :