Growing tip turning brown and dying

[tlintx]

I hesitate to ask, since this is such an experimental crop (very hot and humid out there), but the growing tips on several of my plants have turned brown and died.

Four plants are badly affected -- two at the end of a new bed, two in an older bed. I used "compost" but no manure that I'm aware of.

It's entirely possible I roasted them, but if it's something fatal I'd like to be aware of it!

photo.jpgphoto (1).jpgphoto (3).jpged photo (2).jpg

Edited to add a closeup. It sure looks worse in the photos than it did to the eye!

Tl