It's not chipmunks, it's tomato hornworm,

I was blaming the chipmunks for tomato damage but today when I checked my plants there was too much damage for one or two chippies to manage. As I was reaching under some leaves to pick off a damaged green tomato, I felt something soft against my hand. When I lifted the leaves, Ugh, a huge green tomato hornworm.
I pulled it off and squashed with a paper towel. It was horrid, the squishy stuff that squished from that body.
I had entire branches gone. Chopped off cleanly at the stem. One of my Brandwines was a skeleton.
Hunting brought down at least ten of those green, soft bodies, each one from 3 to over 4 inches in length.
I shall have to do this a couple times a day to be sure I get some of my tomato harvest this year. I've had 4 plants severely damaged already and almost two dozen almost-ripe tomatoes relegated to the compost heap from damage.
There's little that can be done safely except picking off by hand.
Tomorrow, I'll go out with a jar of soapy water to drown them instead of squishing. My stomach can't take that again.
So if you have tomato branches disappearing with only clean-cut stems left, look carefully under leaves and along stems for a long green caterpillar-like tomato hornworm.

UGH!!! GUTTED! I have been there, so sorry about that. It's really amazing how fast those critters can decimate your tomato, eggplant and pepper plants.

BT works on them and is safe for bees and other beneficial insects. I didn't have that many, but had quite a few. I moved mine to a sacrificial tomato plant in the ornamental garden as I love watching the hummingbird moths they turn into. Hand picking is the best and once you get used to watching for them, is easy. Watch the base of the plant for their poop--very easy to see.

I found another huge one when I went to take my kitchen scraps to the compost pile. I thought I got them all, but they are devious. Their color blends too well with the tomato plants.
I'll be out early again tomorrow hunting.

I feel your pain, quiltbea. The little monsters ate about half of my beatiful Jet Star tomato plant, and ruined half a dozen ripening fruits before I found them and pulled them off. Blech..