It has been a rough couple of years for tomato plants. In the northeast, the blight of 2009 wiped out a massive number of plants, and for those of us who didn't rip the entire stalk and all of the roots out of the ground, the subsequent year was also fruitless. Luckily, it seems to have passed, and this year, any tomato issues in my garden can be attributed to my occasional lack of watering and aversion to weeding.
The folks at Treehugger have us covered with the answers to some other common tomato quandries. What does it mean when the leaves turn yellow? Phosphorus or Calcium deficiency - an easy fix with some fertilizer and watering. How about splitting skin on the fruits? That is the result of overwatering - another easy fix.
3 Answers to the Question, "What's Wrong With My Tomato Plants?" from Treehugger