while I think hollow heart is an environmental issue you could be selecting for the problem by planting seed that is susceptible

Randy may be correct but that is just a hunch on my part. It might be prudent to purchase new seed tubers if you can find some locally.

Thanks for your kindly advises. I grow a very popular variety, so buying new tubers should not be, theoretically, a problem, Unfortunately tubers from the commercial sources are heavily treated. I don't feel like bringing any chemicals to my one hundred percent organic garden. Am tempted to give it a try and use my own tubers again.

Garden stores and places like Rural King sell tubers starting any day.