It's hard to tell anything from that pic. Can you post a photo of the whole plant/plants, a closeup of foliage that is just starting to get sick (dead, brown foliage could be from any number of causes), a closeup of affected stems and a closeup of affected fruit?

Absolutely, here are several more pictures. Thanks in advance for the help!

Sorry, I'm having difficulties uploading multiple photos

Most likely the plants are running on the dry side.

The tops/shoulders of the tomato fruits show sunburn/sunscald because of the limited leaf cover.

You're n Sacramento. What have the temps been? If searing, or nearly so, perhaps you need to grow tomatoes in a time frame other than high summer.

Contact your county's Extension Service office. The Master Gardeners there will give you appropriate advice.

916-875-6913

Web:http://cesacramento.ucanr.edu/

Thanks Jean. I'm actually not in Sacramento. I live in much cooler temperatures, in the SF Bay Area on the coast where it never gets hotter than the mid-60s. We are on the cost so most days we have cool, misty weather with some sun mid-day but very mild temps regardless.

Agree that the problem on the fruit is sunscald and that I don't see definite signs of any particular disease. Have you been fertilizing the plants at all? I suppose there could be some kind of wilt at work, but the remaining leaves look like they're suffering more from severe nutrient deficiency. I was expecting to see some kind of gray mold-type problem from your description, but I don't think that looks right. When you contact your county extension, get info on how to get a proper soil test done.

I have fertilized, though perhaps not enough. I will try calling my county extension and inquire about a soil test. I didn't realize that resource was available. Thanks for the advice.

Just FYI, I mix in some granular general fertilizer at plant-out, in addition to putting a bunch of compost and vermicompost in the hole. Then, once plants start flowering and fruiting, I feed them regularly. Every two weeks if I'm using granular and once a week at least if I'm using liquid fertilizer. Tomatoes are not ultra-heavy feeders like squash, but they do best with regular feeding with a tomato-specific formula. The compost and vermicompost are more for tilth and for adding microorganisms. I don't really consider it to be "feeding". There is a small amount of nutrition in compost, but it won't last long. The benefits are more about its contribution to helping you build a healthy soil web, IMO.

If you've only fertilized at plant-out, that nutrition is long since completely used up. In addition, if your soil pH is off, it can prevent plants from being able to absorb nutrition.