Oh, and by the way... I didn't say I keep replanting the spuds in the same bit of ground. That's how you get build up of pests & diseases. I'm fortunate in having a large garden & therefore a large veg patch. I have to put up with bloody botrytis, which affects all Solanums (potatoes, tomatoes & more) and is even more ineradicable than white rot.

Always rotate your crops. Even if you can only shift things 20-30' from where you grew them last year, it helps. Which is what I do (by more than 30'!). I plant spuds from last year's harvest, Steve. But not in the same bit of ground.

And if anyone is wondering about the F1 thing... F1 seeds / etc are (supposedly) the best / most productive / disease resistant, etc, etc. But you're also always told "They don't breed true / don't replant / etc". I can't unequivocally declare "Cobblers" on this, but... The companies who sell you seed want you to buy more seed next year (or the year after, etc). Do you think they're wholly truthful? I've happily re-used Lady B spuds year on year. I've also in the past bought a knock-off bag of s/m spuds (Georginas) & used them successfully as seed spuds. Leeks? Leeks will cheerfully self-seed themselves all over the sodding place! You can grow peppers from the seeds of those you buy. Etcetera. You get the general idea - it doesn't hurt to try, does it? ;-)