The treatment of choice for most people is spraying with fungicides, usually copper based, but you won't get much backing for that idea in this forum. I don't know about septoria, but I understand that late blight needs host plant material all the time to survive (which is why crop rotation can work) and soil fungi are supposed to clobber late blight, so that seems to point to housekeeping and/or sanitation problems over the off season.

I had this problem back when I lived in Exeter, but not here in Tucson, so I'm weather-lucky. In New Hampshire (damp and cool) we kept plants well separated and viciously nipped back. It seemed to work well.

There is some evidence that Septoria leaf spot can be in seeds of affected plants, so being sure the source of seeds is disease free is important. Bordeaux mixture, copper sulfate and lime, is an accepted organic fungicide that has shown some effectiveness in control of both of these fungal diseases.

kimmq is kimmsr