Virus testing seed potatoes: EIR release

Information request and response under the Environmental Information (Scotland) Regulations 2004

Information requested

Details of virus testing seed potatoes in August 2023.


As the information you have requested is ‘environmental information’ for the purposes of the Environmental Information (Scotland) Regulations 2004 (EIRs), we are required to deal with your request under those Regulations. We are applying the exemption at section 39(2) of the Freedom of Information (Scotland) Act 2002 (FOISA), so that we do not also have to deal with your request under FOISA.

This exemption is subject to the ‘public interest test’. Therefore, taking account of all the circumstances of this case, we have considered if the public interest in disclosing the information outweighs the public interest in applying the exemption. We have found that, on balance, the public interest lies in favour of upholding the exemption, because there is no public interest in dealing with the same request under two different regimes. This is essentially a technical point and has no material effect on the outcome of your request.

The answer to your question is as follows:

In August 2023, if it was deemed necessary to use a tuber virus test to determine the final grade for a seed potato crop, a representative sample was taken from the crop prior to harvest. This allows the inspector collecting the sample to ensure that it is collected in a random, representative manner across the crop, thereby ensuring that the result of the testing is a fair reflection of the health status of the crop as a whole. One tuber is taken from each plant sampled and a total of 200 tubers are taken. The sample would have been drawn from the crop at asuitable time, usually after the destruction of the haulm but prior to harvest. The tubers would have been sealed in paper bags and transported to the SASA Virology laboratory for analysis.

In 2023 all tuber testing was done by a ‘growing on’ test. This involves removing a small portion of each tuber, all these portions must contain an eye. These are then grown in the glasshouse and the resulting leaves tested by the ELISA method for the presence of virus. Alternatively, if the results were required more quickly, a PCR test would be done direct from the tuber although this hasn’t been done routinely due to the extra cost involved.

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