Battling early blight (tomatoes)

Sad tomato plant. All its bottom leaves succumbed to
the early blight disease (leaf spot).

I was so excited with the progress of my tomatoes. Really, they were green, bushy, and producing lots of new tomatoes. After my vacation, some of the bottom leaves looked a little worse for wear... they had gotten a little too wet. I trimmed off all the bottom leaves and laughed at my top heavy plant.

But then, bam, the problems started spreading up the plant. A little (a lot) internet research led me to a diagnosis as well as treatment options. My tomatoes have early blight. I probably did a lot of things wrong that led to disease susceptibility: mainly, I encouraged my tomatoes to get bushy and grow upward in the confines of their cage, allowing all the leaves to touch. I also spent way too much time touching the leaves. It rained for about 5 days straight, and it was during this time that I trimmed the bottom leaves and inspected the top ones without washing my hands.

Below, I'll describe what I've learned about early tomato blight, its prevention, its treatment, and my own experimental prevention/treatment ideas.

What is early blight?

Root pruning

Most of my herbs this year outgrew their pots within about a month. Even those that I transplanted to new pots only weeks before had filled them. How did I know? Well, the signs were pretty obvious: