Tim.. You sound like you have have been battling it too for a while sorry to here that it can be devastating I will get some pictures together over the next couple days so we can compare my plants were hit with a combination of things Rhizoctonia started it I think and what finally did them in was Botrytis going into winter..
I have a diffrent spray that proved effective last year for me will get you the name tomm after 2 years of wipeouts this year only lost a handful to it and most were new plants I bought not my own seedlings so progress..
