- Spraing may be caused by two viruses:
- potato mop top virus
- tobacco rattle virus
- The viruses have different modes of transmission but the symptoms are similar:
- arcs of necrotic tissue in tubers
- Cultivars differ in resistance to spraing, check British Potato Variety Database.
- Other control of the diseases is by controlling the vectors.
Potato mop top virus
- In wet soils in particular, spraing may result from potato mop top virus (PMTV), transmitted by powdery scab.
- While PMTV is usually associated with powdery scab, it may also be seed borne.
- Development of spraing symptoms due to PMTV is greatest at low temperatures.
Tobacco rattle virus
- In sandy soils in particular, spraing may result from tobacco rattle virus (TRV), transmitted by free living nematodes.
- Free living nematodes may be present in a field without being hosts of TRV; nematodes may be analysed by a laboratory to determine whether they carry spraing. More …
- TRV may be maintained in soil in seeds of susceptible weeds, e.g. chickweed, shepherd’s purse, common red poppy, therefore weed control in potato and following crops is important.
- Barley is not a good host of TRV, therefore barley crops in the rotation may reduce the incidence of spraing.
Recent research on diseases 2008 (Includes PMTV biology and transmission)
Pest control updates 2006 (Includes control of free living nematodes and spraing transmission)
Testing for tobacco rattle virus 2005 (Nematodes can be tested to determine whether they carry TRV)
Spraing transmission 1996 (Transmission of TRV by free-living nematodes)