I have no experience with salt rising bread, but have read that inhibitors used to prevent potatoes from sprouting can kill the bacteria the starter is trying to grow. The recommendation was similar to NoraC's suggestion: organic potatoes. In fact, organic ingredients all the way.
See: Salt Rising Bread Starter | The Fresh Loaf
AJ
I have a starter going at this time. I used Pure Stone ground cornmeal, flour, baking soda and scalded milk. I believe the hardest part of making this is getting the temp. correct while it is sitting for 24 hours. Must be around 105F. I am crossing my fingers that by evening my house stinks....hahaha