Any chance of herbicide drift from anywhere in the vicinity?

Yes! I think the utility company sprayed stuff beyond the back fence where their lines get covered in vines. Jeez, I'm glad my tomatoes weren't out yet.

Cut the damaged part off right away. Cut it down to a set of leaves on the stem. The plant will grow new stems and be fine.

The highway dept. sprays weed killer here, along the roadside, and it kills the rare wildflowers in the streams next to the road. It makes me mad.

Good luck with the plants!