Welshonion and you would be wrong about comercall growers spraying tons of chemical and pesticides.
the reason commercial growers use the varieties they do is the varieties are hardy less desease prone and grow well in variety of weather condition. farmers need crop to be consistant since crop failure means they may lose there farm and grow broke.
Birdwatch, I'm afraid you're wrong. Of course commercial growers need their crops to be disease free and consistent croppers, but the varieties grown are chosen by the supermarkets with whom they have contracts to supply - but take it from me that in order to achieve the quality required by the supermarkets, commercial non-organic potato farmers apply a large number of treatments throughout the season. See here
and here http://www.potato.org.uk/news/desiccation-programmes
plus the broadcast application of slug pellets at frequent intervals throughout the growing season. I can assure you that these treatments are also practised by potato farmers in the USA.
As I said, my brother is a large commercial potato farmer.