Thats 100% bacterial wilt. I dealt with it the year before last. As far as i know, after its affected all you can do is get rid of the plant. Cucumber beetle spreads the bacteria, and only prevention is to prevent the cuke beetle. Weird thing, it affected one of my plants, i pulled it up and have never had a problem with it again, and i usually have a lot of different varieties of squash in the summer. It may be a more regional thing as well.

http://vegetablemdonline.ppath.cornell.edu/NewsArticles/CucBW.htm

Concur that is SVB damage since the plant appeared 100% healthy yesterday. Wilt usually affects individual or groups of leaves as it travels to the stem. The plant MAY be saved if you extract the grub and mound dirt over the affected section of stem.

SVB really? Maybe i am wrong but bacterial wilt affected my squash plant exactly like that, and overnight unless i wasn't paying attention.... Dig in the stem so we know for sure! Now i am very curious.

I agree also it's SVB. The whole plant going from great to dying just like that says the heart of the plant has been damaged by the vine borer.

A near-universal symptom of the borer is frass. It will look like saw dust and can be dry or moist. It will usually be along the main stem, and most often, depending on how far the worm has traveled, towards the base of the plant. Usually you'll find it in little 'piles' next to a tiny hole on the stem

Unless I'm going blind I can't find anything around the stem but will look more closely tomorrow, I do have plastic down, Wouldn't that keep the borers away or do they enter from the ground into the main stem?

I apologize if this is a dumb comment, but the plant doesnt just need water right?

I don't think so, We have been having rain on and off which is making everything grow.

they enter from anywhere. it will be difficult to slice that trunk properly, you may have to sacrifice secondary stems. you have nothing to lose in doing surgery, because if you do nothing the plant just gave you the last zucchini.

When the plant keels over, it is time to seed turnips in its place.

I've seen squash plants do that from squash bug hatchlings (NOT cucumber beetles) feeding on the plant. Have you been checking for the orange egg masses, usually on the underside of leaves?

Same thing happened to me two summers ago. I had two zucchini plants growing next to each other; both looked healthy, grew quickly and produced some fruit, then one day out of nowhere they both wilted like yours above. I thought it had something to do with heat, since this happened during a particularly hot, humid stretch, and the timing seemed too coincidental to be SVB. Extra watering seemed to help perk them up temporarily, but the wilt continued. Ultimately one of them died, the other hung on through the season but didn't put out much more fruit.

Yesterday afternoon around 3pm with Captain Jack I sprayed then poured the rest of the liquid down the center and around the base of the plant, Last night we had a lot of dew and the plants were all wet this morning, Now I know every morning when I go out early the plants are all standing up nice until the heat of the day hits them, But the infected zucchini plant was looking better, Some of the leaves were perked up as well as some flowers, I will wait until later this afternoon to see if the plant is still looking like it is doing better an if it is I will post another picture of it.

I had 2 yellow crook neck squash die overnight a week ago. watering did no good. I pulled them both and sliced them open and nothing was inside of either one.

I have had that happen and done that and think you have a losing battle.

For my own purposes I did a little research on bacterial wilt because I have seen a few cucumber beetles out there.....and some of my cucumber vines are wilting in the searing heat but do not with shade cloth and recover overnight and are producing.

http://www.ipm.iastate.edu/ipm/hortnews/2011/8-24/cucurbitwilt.html

Just want to say thanks too everyone for your time, That was a good site and good information, Plant still looks good and I have my fingers crossed, Also I do have an extra plant that's about half the size of the others just in case something like this happens.

It is always good to have extra plants Jimmy! I have lots of room, so I plant them in stages, about 2 weeks apart. I have way too much squash from my 6 surviving plants and the newer ones are starting to bloom now. The next 6 are growing like weeds. Thank goodness I live near a Church that has a food bank for my extras!

Here is some updated photos, Maybe there is hope as you can see in photo 1 the leaves aren't drooping like they were but look awful yellow and in photo 2 you can see some green healthy looking leaves in the middle.

I would at least cut off the yellow leaves, they are hopeless.

Forgot to mention that I did, Thanks.

I have had borers so many times (not yet this year under cover), and the plants never wilted that quickly-plus there would be obvious stem damage with frass before the leaves wilted. I have always had stem and branch damage before wilting. Days and days. I never had bacterial wilt, but just the name of the illness may hint at that what it may be?

Thanks SS, I did spray them good about 3 days ago with Spectracide 51000 Immunox Multi-Purpose Fungicide.

glib 5.5 why plant turnips? I'm curious. Is that a way to control the grubs and rid the soil of infestation? I have four plants that got hit by what looks like powdery mildew but then the svb showed up. I thought the mildew weakened the plant to allow the svb to do its job. Please tell me about the turnip idea.

Thanks for the info. I managed to find a larva in each of my zucchini plants. One I feel as if I rescued and the other...well we'll see.