Anyone expecting a frost in the next few weeks should ruthlessly prune plants -- any blossoms should be removed, as should all of the branches that point downward. Here in Minnesota, come late August, I wack the heck out of my plants so that all of the energy goes into ripening the tomatos, not sustaining greenery. And, if you have too many of the ripe ones to take care of immediately, and intend to use for canning and sauces, freeze them whole. Don't cut the core out, and try to keep the skin as intact as possible. When it's time to use them, run under hot water and the skins will slip right off. Put in pot, and when they are thawed, it's pretty easy to pop the cores out.
