Yeah, early blight for sure...do you use a mulch under your tomatoes at all Dave? That can help a lot with the splash up diseases, as can watering in the AM rather than at night...
[url=https://www.engageagro.com/media/pdf/msds/daconilultrex_msds_english.pdf]Daconil[/url]? On a food crop? Read that MSDS, Dave. Possible carcinogen, [url=https://www.engageagro.com/media/pdf/msds/daconilultrex_msds_english.pdf]low level toxicity[/url] for humans...ewww...the Extoxnet page says it stays persistent in plants and some metabolites do make it to harvested fruit... and we haven't even begun to talk about what it does to the environment... I can't tell you what to do, Dave, but I can ask, please don't go there... we just got you here...
I have harvested good fruit off of plants blasted with early blight; you can help them through this but not by killing every fungus in a ten foot area, including mycorrhizal fungii supporting your tomato's root sysytem, or the
Trichoderma fungus that has been killing a lot of other fungii that
didn't end up attacking your plant. You need those guys.
Mix milk to water, one to ten, and add a splash of fish hydrolysate, and water leaves with it after every rain or foliage wetting. This encourages
Lactobacillus bacteria that have low level antifungal properties to colonize the leaf surfaces, called antagonistic biological counterculture, and no matter what you call it it sure does help with early blight. Also the calcium in the milk is very important here as well; seems calcium deficiency in plants is a key factor in early blight. Liming the soil will help next year, but milk gets it into the plant much quicker than a mineralized form.
Spread some good mulch under your tomatoes to keep water borne disease from splashing up. And develop good live soil ecologies that inhibit badguys, who are only 5% of the total biology mix in a healthy environment. Neem oil has proven somewhat effective, but only when caught early, and that does not seem to be the case here...
I prune off the lower foliage as soon as plants are big enough to allow; by the time they are three footers the bottom foot of foliage has been sheared off, and with everything above, I stay pretty clean. But I had a plant or two hit hard last year and eked them along until the fruit ripened; you can do this. Keep pruning off the dead as soon as you see it going and treat them like I said and you'll get through this...
HG