Virus Testing

SASA is pleased to inform you that the SASA Virology Laboratory will resume the commercial virus testing service for potato crops for the forthcoming 2024/2025 season.

Potato-infecting viruses cause significant damage worldwide and represent a significant threat to seed potato industries. The incidence of virus in seed potatoes can have a significant impact on crop quality (both seed and ware). Virus can result in seed crops not meeting the official standard for a class (downgrading) or even for certification as seed potato (failed). The presence of virus in seed potato crops may also enable damaging spread of virus during the growing year. There are about 40 viruses infecting cultivated potatoes, some of them like Potato Leaf Roll Virus (PLRV) and Potato Viruses Y, A, V, S, M and X are distributed worldwide in potato-growing areas.  

Virus testing is carried out mainly in support of the Scottish Seed Potato Classification Scheme. In addition a service is provided in support of the wider seed potato industry in Scotland. Tests are carried out for the following viruses:

  • Potato Viruses Y, X, A, S, M, V,
  • Potato Leaf Roll Virus
  • Tomato Black Ring Virus
  • Potato Mop Top Virus; and
  • Tobacco Rattle Virus.

Virology Laboratory
Virology Laboratory

Services include:

  • Tests on samples submitted by Scottish Government Agriculture and Rural Economy (ARE) inspectors during the course of growing crop inspections
  • Postharvest tuber testing of contravention seed potato stocks.
  • Virus health surveys of seed potato crops in support of the Scottish Seed Potato Classification Scheme 
  • Postharvest tuber tests on samples destined for export to ensure that they conform to the requirements of importing countries
  • Diagnosis of potato-infecting viruses in samples submitted by growers and agricultural advisors.

The following test methods are employed:

  • ELISA (Enzyme linked immunosorbent assay)
  • Real-time PCR (Polymerase Chain reaction)

Please note the following Instructions for commercial virus testing for potato crops:

  • Virus testing requests must be booked in advance 
  • Complete and return the signed Virus Testing Request form by email to the SASA Virology Laboratory at virology@sasa.gov.scot. Your request and booking will be confirmed by email
  • Once booking has been confirmed by the SASA Virology Laboratory, send your samples to: SASA, Virology Laboratory, Roddinglaw Road, Edinburgh, EH12 9FJ, UK.
  • Samples will be disposed of, or returned at the customer’s expense, if the laboratory has not been pre-notified and confirmed the booking
  • All samples should be packed securely and sealed
  • It is suggested that a copy of the Virus Testing Request form should be included with the sample (the form should be kept clean and dry) for traceability.

Advice to our customers

The accuracy of a post-harvest test result depends on the number of entities (i.e. tubers) sampled from a crop. The validity of test result calculations for the sample submitted is based on the following assumptions: 

  • A “representative” random sample of from a crop is taken 
  • The infected tubers (if any) are evenly distributed across the crop
  • The number of tubers in the sample is no more than one-tenth of the total number of tubers in the crop
  • The minimum recommended sample size is 120 entities (greater sample size will increase accuracy)
  • Tests results are only valid for the sample received

Follow the links to download the current Virus Testing Price List and the Virus Testing Request Form.