The seed sector makes up around 11% of potato production in Great Britain. Most (c.70%) is planted in Scotland, where unique growing conditions help to assure the high health status of the seed.
GB typically exports 16-17% of their total seed crop each year. Around three quarters of UK seed exports, c.70Kt, is destined for non-EU countries. Egypt is the largest market by far, purchasing approximately half of all UK seed exports. This is followed by Morocco with a smaller but still significant proportion (c. 10% of all UK seed exports). Within the EU, they ship the most to Spain and the Canaries (c 10% of all UK seed exports); the Netherlands and the Republic of Ireland are also key destinations.
Imports vary from year to year depending on the availability and price of domestic seed, and industry requirements for specific varieties. Most of this comes from the Netherlands for use by growers in England and Wales. According to APHA, around 30Kt of seed was imported in 2018-19 for this purpose. In Scotland, a voluntary arrangement with industry is in place meaning only locally sourced seed can be used. This was set up to maintain the high health status of its seed by making sure disease is not introduced through imported material.
In the event of a no deal exit, both tariff and non-tariff barriers will come to bear. For non-tariff barriers, the UK would be unable to export seed potatoes into the EU until the UK is granted third country equivalency. Varieties registered on UK National Lists but not the EU Common Catalogue would no longer be marketable in the EU.
Tarrif barries entail that tariffs would apply to all destinations, whereas previously Egypt and Morocco had a tariff free arrangement. If current tariff rates stand, these would be 2% to Egypt and 2.5% to Morocco. If third country equivalence is granted for exports into the EU, the tariff rate would be 4.5% at current tariff levels.
Most non-EU seed is exported in November and December each year. So, as the current deadline of 31 October stands, it would be difficult for arrangements to be in place in sufficient time.
The largest export tonnages to Europe are shipped from February to April. If the EU does grant the UK third country equivalence soon after the current 31 October deadline, there would be a short time for an agreement to be put in place. If the EU denies the UK third country equivalence status, or delays the decision, then seed intended for export could end up in the domestic market. The resulting extra supply could put local prices and businesses under pressure.
If third country equivalence status is granted, seed intended for EU markets may still need a phytosanitary certificate or additional testing to comply with EU regulations. This may make exports to the EU more expensive and less competitive for GB against European counterparts.
For more information: 
AHDB
Tel: +44 024 7669 2051
Email: info@ahdb.org.uk
www.ahdb.org.uk