From Faisal islam, BBC news online:
<<< The UK government has told the agricultural industry that the EU will allow almost all food and plant exports from Great Britain to continue after Brexit.......
....And whereas the export of Ware potatoes for eating is still permitted, there will be a ban on exporting seed potatoes - that is, potatoes which are not meant to be consumed, but are planted in order to grow more potatoes......
....The Defra letter says: "Unfortunately the EU have confirmed they will not accept our case for a permanent change to the prohibition on seed potatoes… on the grounds that there is no agreement for GB to be dynamically aligned with EU rules"......
.....This is an industry significantly focused on Scotland and the north of England.
Exports of seed potatoes will also be barred from Great Britain to Northern Ireland. A continuity trade deal with Egypt will protect the largest market for British exports.
Scottish government rural spokesman Fergus Ewing said it would be "disastrous for our world leading industry">>>
I think the farmers of Europe will not be pleased with this as our seed potatoes are the best
But the potato growers of Egypt will be happy - all the more for them
What the 'dynamically aligned' bit means I have no idea in this context.