Not exactly sure, but I'd be spraying with a fungicide.

I could try that but why just those two and not the others. Maybe they are more susceptible?

Spray now ask questions later. One of my tomato plants had bad aphids, and the other two didn't. Two of them had septoria leaf spot, and the other didn't. Nature is funny. Treat the symptoms as they occur.

Any recommendations on what spray to get? Never had this before

I use Daconil. I buy the concentrate and mix it for a hand held sprayer. I usually spray once per week. Sprayed a lot early in the year when we had rain and heat. Not too much lately with the dry weather and low humidity.

Looks like a serious nutrtional deficiency to me. Could the soil in that spot be too wet?

I thought about a nutrient problem, but didn't think it would only affect the bottom set of leaves. I've seen wilt work it's way up from the bottom. Does seem odd though that it's only 2 plants.

Nanelle, They all get the same amount of water. We did have a lot of rain(at least for here) for the last week though. The soil is also exactly the same when I filled the beds.

Yellowing of bottom leaves is usually a sign of Nitrogen deficiency. The plant is able to scavenge the Nitrogen from the bottom leaves and send it to the growing tips. Bottom leaves yellow and then fall off.

I'm not sure I'm looking at the photo right. I think I see the bottom of the plant, and two or so sets of leaves, and then perhaps the leg of a wire cage behind it, but I don't seem to see the top of the plant. Am I missing something?

If you haven't, I would check the soil moisture a few inches down on that plant just in case. In additon to nitrogen deficiency, I think soggy soil is a pretty common cause of iron chlorosis in alkaline soils. Not sure if it's the old leaves or the new, but I've certainly seen it before.

ETA looked it up; yellow old leaves= nitrogen deficiency, yellow new leaves = iron chlorosis. Yellow leaves from soggy or compacted soil=lack of oxygen to roots.

Why are my plants turning yellow?

I have a bag of Ammonium Sulfate 21-0-0, would that help it?

That kind of bright, solid yellow makes me worry about soilborne wilts. They can occur in one plant and not affect the one next to it when they first appear. Lots of factors involved. Different varieties also have different levels of resistance, too.

nanelle_gw, I just took a pic of the yellow leaves I had just cut off, the rest of the plant looks great and even has fruit on it already.

Just keep an eye out. The "yellow flag" symptom often precedes general wilting and other symptoms. There aren't that many other things that will cause such a uniform and bright chlorosis.