Tomato Wilt

You don't give us much to go on.

Humid or rainy conditions Poor watering practice, water splashed up the leaves carrying spores and making damp Not enough air circulation and sun Planting in the same bed, ie not rotating Using susceptible cultivars ...

The first you cannot do much about, if you have 2 months of overcast and warm summer drizzle you can forget your tomatoes. The rest you may be able to improve.

David

None of the above apply. I looked at the web site sent to me a few more but I still can't figure it out. They talked about bacteria in the soil but wouldn't that destroy everything else? Very Frustrating. What if I cut off the leaves/stem that have wilted. I guess it couldn't hurt

The short answer to your question is, "not necessarily." The bacteria will destroy anything that is susceptible and has no resistance. If the plants around the tomatoes are more resistant then they won't be as affected if they are affected at all.

Find the book "What's wrong with my plant (and how do I fix it?) : a visual guide to easy diagnosis and organic remedies" by David Deardorff and Kathryn Wadsworth

IIRC it uses a flow-chart model of diagnosing plant problems and the process is very straight-forward.

How many cultivars have you tried? How do you know the ones that you have tried are resistant? Sometimes trial and error is not a bad procedure.

Have you tried taking some of the affected plant to an expert for identication?

If it actually is a wilt this may help: