Cooked roots or poor drainage? Have you done this before in black platic bags with that soil? Also appears to be some type of crown rot in the pic of the dead one.

tj

What are the containers filled with? If regular soil, I bet that's at least part of the problem.

First guess is you are cooking the roots. Fert may have exacerbated stress. First pic looks like ordinary garden soil in bag, not sure why that was done, surely a cause for decline. Second pic looks like cooking the roots and suffocating them in a mixture of garden soil and potting mix.

Containers should be potting mix only.

Dan

Cooking the roots is an interesting theory. But it's been relatively cool all this time, highs of 80 or less. Yes, it is garden soil (essentially almost pure sand) mixed with some compost. I have a bunch of grape vines happily growing in that mix. I have one bag with a tomato planted in potting mix, that tomato does quite poorly. The biggest tomato plant I have grows in pure garden soil without any amendments.

I flushed the plant in the first picture with a couple of gallons of water, to get some of that fertilizer out, we'll see what happens.

Cool temps are one thing, black surfaces absorbing maximum solar incident radiation is another. Combine that with garden soil in containers inhibiting moisture movement and harboring pathogens, and you have an excellent chance for encountering problems.

Scroll thru the 'Container Gardening' forum on this board for discussions on the issues with native soil in containers - should be ~hundreds over the years.

Dan