You said: Here is a link to pictures of my tomato's. I was wondering if the brown leafs are normal or if I am doing something wrong. Maybe they are the determinate and starting to die?
My primary point to you is that the active ingredient in Daconil is Chlorothalonil. Bonide's Fung-onil uses the same active ingredient in about the same percentage. I use either, whichever is available.
Others may have mentioned this; but the key to the use of these fungicides is to use them as early as possible, and frequently. It will typically not eliminate the problem, but will significantly slow its advancement.
I believe others said that some varieties are much more susceptible to this than others. This variation in susceptibility is also true of wilt, which is soil borne and systemic and for which there is no cure. I usually pull those plants. But you are not experiencing wilt. Wilt is unmistakable in its appearance.
My modest input to you after years of the battles--open to correction and input. DaveH Chambersburg, PA