Leaves that yellow at the bottom are a common issue here. We pull them all off and destroy them, since soil borne problems are not unusual.
Sometimes yellow leaves mean a shortage of nitrogen, or one of the trace elements/minerals.
There’s just so many things it could be, it’s hard to pin down. I usually check for aphids and bugs first. Then I pull off the yellow leaves and give it a good dose of fertilizer, and watch to see if it recovers.
If hubby has to use an insecticide, he uses one that is dispersed by morning, so that it won’t hurt the bees, and he won’t use it on anything once blooms are all around. I just stick to pepper/onion/garlic mix.
Sometimes yellow leaves mean a shortage of nitrogen, or one of the trace elements/minerals.Thank you! This could be an issue.
I suggest visiting ‘tomatoville.com’, they have lots of suggestions for foliar diseases on tomatoes. Yellow leaves on MY maters usually means some form of early blight. Augh. Another learning experience I could very well have done without!
Here’s what I do:
Take 1 gallon water, exactly. Put it in a new (unusued for anything else) pump sprayer. Add 5oz exactly of the new Clorox bleach concentrate. Mix thoroughly. After sundown and the bees (if you’re lucky enough to have them this year) are gone home for the evening, spray the heck out of the tomato plants. They will look like hammered heck while every infected leaf goes ahead and dies. I follow up with a feeding of some sort. Any uninfected new growth will be fine. But this kills the fungus/whatever to prevent any NEW infection.
Try this with one tomato plant first.
Another thing that prevents transfer of soilborne diseases is to mulch with papers/hay or just hay. Anything to keep the soil from splashing up on the leaves when it rains.