The leaves on some of my tomato plants are turning brown and getting crunchy overnight. does this ring a bell to anyone. it seems to be spreading.
They look very purple. How cold has it been? LInda
Spider mites can do damage this severe. Look for signs of web-like structures on leaves (top and bottom). Look for web-like structures between leaves and stems. There was something on the leaf in the second picture that looked a bit like a web, although I don't see anything in the other photos.
Spider mites can be difficult to eradicate.
I'm assuming that the purplish hue in the pictures is just the colorization from the camera and that it's actually a bronze-ish brown.
If it's not spider mites, then I would consider the possibility of a virus, possibily Tomato Spotted Wilt Virus (link to pics of TSWV below). TSWV is transmitted by thrips. It's been quite common over the past few years in many parts of the country.
But before we jump to a possible virus diagnosis, let's eliminate the spider mite possibility first.
Here is a link that might be useful: