Another Photo

And another photo

Not a disease.

I see a mixed bag of signs and symptoms.

Start with this: Anywhere near your affected tomatoes?
http://forums.gardenweb.com/forums/load/pests/msg0622525817906.html?2

Here is a link that might be useful: tomato problem

Yes they are in the same bed together. I read the other page on herbicides and I remember that I spray weed b gone on the grass that is now some 6 inches under the effected bed. I have 6 beds and only the one shows the severe symptoms. My black diamond watermelon and one cantaloupe plants leaves are brown on the edges, but the new growth looks fine. The leaves flatten out the older they get and I do have blossoms emerging. I thought it might have something to do with me changing the ph in my soil. They were growing very slowly and the ph was around 7.8ish now its around 6.4ish and they have allot of new growth.

The "flattening" of the leaves of sensitive plants will gradually merge into brittle and tightly curled/distorted.

Herbicide damage.

They start curled and flatten out. not sure if they are brittle but a couple of my cantaloupe plants seemed quite brittle when I transplanted them in an adjacent bed.