When is a seed potato too small to plant?

Ivor.We used to grow c15 acres of spuds a year to sell at the door and to our local outlets.We bought new basic seed every year to put through an automatic planter.We needed as big a crop as we could for obvious reasons.having said that we had a reputation for good flavoured potatoes and not forced and poor cookers.Getting back to your concern,we liked a smaller set to sit on the planting cups so they would not roll off and make the row gappy.We lost a proportion of "sprits"as we called them and it made no difference to the size or yield per acre.What did reduce crop yield was crop nutrition.If after all,a fire will only burn well without plenty of food shovelled onto it!As with potatoes,correct NPK in the seedbed,and seaweed foliar sprays when growing did the trick.A wateringcan full of seaweed extact stuff from the garden centre is the stuff to use,in the plot situation.I have always remembered an old farmer years ago saying a potato crop is an honest crop,cut down on attention to nutrients and you get what you deserve---- little in return.I hope this helps,excuse the rambling on!!  John.

Ivor. Yes some would be well under the minimum riddle size for 35x55's,maybe nearer 25's,and being a bit tight with the £'s then they went further per acre,too!! john.