Potato scab

Hi I wonder if anybody could suggest a reason for scab I had some last year for the first time in about 4 or 5 years of growing spuds in containers, so this year new containers bought fresh compost and of course new seed and still have scab on some of the spuds only looked in 2 of the bags as yet. I know it does'nt make much differance with regards to eating but we have a small village show and I like to enter a few bits and pieces.
Any thoughts? Eric

 

I'm really not sure,maybe could have done with a bit more water

 

Very possibly, as Loli says, a lack of water may have contributed.
An old preventive remedy is to scatter grass cuttings in the trenches when sowing - though I can't comment on how well that works as I've never got grass long enough to cut when I sow my first spuds.
You may find the RHS info regarding scab helpful for the future, but too late for this year.

http://apps.rhs.org.uk/advicesearch/profile.aspx?PID=230