My experience with Septoria, or whatever it is..
 

I grew some nice tomatoes a few years back, and then had two seasons where the tomato season was interrupted by one of these blight type diseases. I did another soil test in 2009, using three locations in my garden. To my surprise the phosphate levels had dropped below the acceptable levels, and I had tested only three years earlier. I had some idea that using as much compost, worm poop and other organic things would take care of the NPK levels. Apparently, they do help the nitrogen and potash need, but not much for the phosphate, according to the soil test results. In 2010, I started using 10-10-10 along with the compost and I could see a turn around for that season. Then in 2011 I decided to really experiment and used some super-phosphate along with the 10-10-10, and the results really blew me away. I only used the super-phosphate(0-45-0) on selected items, like my heirloom tomatoes and sweet potatoes. The tomatoes grew as they should, producing well into late August, and of great size and flavor.
The sweet potatoes really reacted with the biggest potato coming in at 5.5 pounds! Since then I have done well with most of the garden, using the regular fertilizer, and selectively using the super-phosphate. The thing I learned is if you go back to the basics of having your soil balanced, the plants will overcome many of these diseases, which will return if I don't supply the necessary ingredients.

Dino
How did your tomatoes do in 2015. Did the septoria return?

disease
 

-Yes, I started out the usual way, with tomato plants growing very strong, and then, just after the fruits are setting, the brown leaves show up on the lower branches. It works out likeI was growing 'determinate' varieties, where I get one main crop, and then the plants die off, ending my season in early August. Do you have the same result?

Yes i have the same results here in the piedmont close to greensboro. So the extra phosphate didn't help i guess. I relly hate to use daconil, have you tried it yet?

I was under the impression that if my plants were really strong, they might overcome these diseases. I guess that might be true to a point, but this disease seems to be in the soil and affects the plants, no matter what. I have tried using the dust for funguses and putting cardboard down to keep the plant leaves from contacting the soil and some other 'fixes', but nothing seems to work. I must say the phosphate really works best for my sweet potatoes with the average potato coming in at over 3lbs, and the biggest at 5lb 3oz. I haven't tried "daconil' or heard of it before. Was it developed for these tomato diseases? I'm in the Mt Airy area if I didn't mention it before.

Many people on here use daconil and say it helps as a prevention. I have not used it because it allegedily can cause cancer in humans, but no proven cases as far as i know. I lose my tomatoes every year to different kinds of blight. Trying a hoop house this coming year and planting some determinates to see if i can get a crop before the june diseases start up. Also plan to use actinovate and excel lg. Hav not tried them yet. Folks on here have said good things about them.