bummer, that looks like SVB got to it. Is there any sawdust looking frass around the base or anywhere before that point on the vine? if so, it's probably a goner. next time cover the vines with dirt as they grow, and it will send down roots, and will be able to withstand.

Well you have two opinions and im going to build on them look closely at all the vine from near the root right where it comes out of the soil a little deeper and from there along the vine if you find a mushy area that has rot with a hole it is a vine borer very carefully cut length wise in the vine gently and find and remove it(the vine borer that is) be careful not to slice all the way thru the plant stem by accident like I did once then after that gently bury that part of the stem and water it with fish kelp emultion mixed with a little aspirin water the root alot extra with that solution so it can recover (BUT IF YOU CHECK THE WHOLE STEM FROM ROOT TOWARD THE END AND YOU FIND NO VINE BORER OR OTHER PEST YOU BETTER DIG UP PLANT WITH ROOT AND SOIL INTACT AND THROW IT AWAY WHERE IT WILL NOT INVECT OTHER PLANTS OR PLANTING MATERIAL CAUSE IF ITS CONTAGIOUS WILT IT WILL KILL YOUR OTHER PLANTS AND SPREAD LIKE WILD FIRE

Instead of massive surgery, one thing I have done is this: ( Think of it a cleaning out clogged plumbing)
Get a good spray bottle that you can adjust to have a good strong fine stream. Fill it with water (I sometimes use soapy water, or other times BT solution, but regular water will work good too) Then spray up the hole with frass coming out.. spray it really well, trying to fill up the infected cavity with water as much as you can, and in the process, cleaning up the affected area. Often the SVB caterpillar will try to come out, since its being drowned. Then I get a thin electrical wire (one that is soft, and has many copper filaments that are sharp, and I remove a little of the insulation to expose the sharp metal). Then I use the wire and probe inside the affected stem with it, both above and below the hole. Often it will impale the grub, and in a sense, I am snaking out the grub with it, like a plumber would do. I do that and keep washing out the cavity with the spray water, until I am fairly confident I got them all. (sometimes its several per hole). That works pretty good without doing much additional damage to the stem.
I should make a Youtube video some day :)

My pumpkins looked like that. In my case it just turned out to be wilt from the heat.

I'm in the Dallas area too, and my pumpkins never look that bad unless that part of the vine is infected by SVB somewhere along the vine, and it has not had a chance to root somewhere else. So I don't think the heat did that, unless it was just not watered enough.