Below are some lower leaves from 2 of my tomato plants. I'm worried that whatever has hit them the last 2 years has begun again. Always begins at the bottom of the plant, turns leaves yellow with brown spots, the the branch dies and literally falls off the plant and works it's way up till there is nothing left. I know that tomato plants do sometimes turn yellow on the bottom leaves but I don't think this is the case.
History: This is the 4th year I've worked this garden. It's small, only 15x12. Not a lot of room for rotating. The first year was amazing. Two years ago I got maybe 20 tomatoes from 25 plants. Last year it held off a bit longer, even though it was a very wet spring and early summer here in the mountains of WNC. This year I decided to make some changes. Firstly, I covered the garden in chicken poop and tons of dead leaves last fall, after the growing season was over. This spring, the first thing I did after planting was covering nearly every piece of exposed garden with cardboard. Since then, I've been meticulous about trimming any leaves that touch the ground. I've also for the first year begun using soaker hoses, from underneath the cardboard. And finally, no fertilizer. I stressed my plants once each of the last two years and I thought maybe I had weakened them, allowing for easier infection.
Until today, so far so good. Everything is growing awesomely. Nearly every tomato plant has tomatoes started. But went out today and found 6 or 7 stems that had begun to turn on 2 plants. If this is disease again, I'm at a loss. Can anyone help identify and maybe give me an idea of what might be done...before I write off the whole thing again before investing any more of my time? Thank you!