Have you given a good look to check for possible cane borers within those wilted stems?

Well for anyone following this I never did conclusively figure-out what was happening. It was a very wet spring and summer and I noticed significant decline and mortality of a number of the plants after a particularly rainy series of weeks. So my conclusion was that they are struggling from over watering. We installed some underground drainage in our yard this summer which will hopefully take the pressure off the plants that survived. Here's a few pictures from today. They look pretty sad. I'm considering cutting them all back to the ground this winter, just in case I'm wrong and it's some sort of disease or insect damage that I'm missing.

(Please overlook the grass, I need to do some serious weeding here)

Daniel, thanks for the follow up. Yes, sound like you have had a very wet season causing the demise of the plants. Besides, the drainage system installed, any chance of raising the area up with additional soil to further assist the issue?

yep that's definitely a possibiility. I asked the drainage installer to pile the extra soil near the garden for that exact purpose. So hoping to raise all food growing plots a bit to help with drainage issues.

Yes, good on you both installing the drainage and raising the ground level, hopefully desired results achieved. Other than a region of my front lawn, the rest of my entire large acreage yard is nicely contoured and sloped, A neighbor once commented that my veggie gardens would require more watering for the hill in which it sits, I said her place is opposite for being low and flat, the next summer her garden became a literal lake for the deluge of rains that even many of her fruit trees had sustained damage,