dying tomato plants
by Dan
(North Platte Nebraska)
Doug hesitates to say this but you might consider reading the how-to-grow tomato pages as a good first step. I can't see from the picture what exactly is the issue but you may have verticillium or one of the blights.
All the info on how to grow great tomatoes and how to avoid these problems is here. (Scroll down to the tomato section) It doesn't make a lot of sense for me to repeat it all here (and I don't have the room to do it in this tiny box) :-)