Recommend you just start some more seeds, if these plants don't make it Mary. Seeds are cheap, and chemicals are expensive.
I had some Serenade a few years ago, and it's a very good product, and registered for use on edibles. But to be honest with you I stopped using it because I couldn't stand the smell of it. It's also really expensive. Please be careful what you treat your plants with, that they are ok for use on edible plants? I don't think Daconil is something I'd want to ingest. Systemics of any kind get into the plant's system and can transfer to the fruit.
Other than the peroxide douse, (very seldom) the only chemicals I use on any of my edibles are Bt, soapy water and baking soda/water sprays. Blight is not a fungus, it's a bacteria so a fungicide isn't going to work anyway.
Haven't had any serious problems except at the end of the season when I was pretty much expecting the plants to die off anyway. It's mysterious to me how your soil got infected - were the pots sitting on the ground? Could something like weed killer or a lawn treatment spray have blown onto them to cause the leaf burn and spotting?
