A borer would not kill it that quickly. You'd better post a photo.

Maybe your neighbors don't want to be deluged with gifts of zucchini this summer and they poisoned it for you. :)

Just kidding-- that would be awful! Hope the rest of your garden remains OK!!

This a more than a little weird. I have three zuchinni plants. Wednesday night, it rained for the first time in four weeks at our house. Early yesterday morning, all zuchinni plants looked healthy and happy. (I have kept them watered regularly in absence of rain.) Got back from shopping just before noon and saw that one, only ONE of the zuchinni's had suddenly wilted and looked like it was quickly dying. Checked the plant for insect damage, and checked the soil around it. Soil was still moist, no evidence of insect attack. Everything else in the garden looked great. I gave the shrivelled plant some water anyway just to make ME feel like at least I was doing SOMETHING. At end of day, the plant looked worse and I assumed it was dead.

Got up this morning to pull the plant with intention of planting seed to grow a replacement. To my shock and delight the plant was completely recovered. I have grown a good amount of zucchini over the past few years. I have never seen anything like this happen.

I wonder if it's possible that this one plant out of all else in the garden was overcome by the fact that it actually rained, and it fainted :~).

Seriously, I do hope someone can help solve your zucchini mystery.

This problem has happened to me each year, maybe just one plant will die or sometimes many. Upon dissecting the vine it shows damage to the inside from bores. At times it may be the upper section of the plant and other times the complete vine will die. Squash Vine Borer

Description: White larva with brown head, up to 1" long. Preferred foods: pumpkin, squash, cantaloupe, cucumber and gourd vines. A small pile of "sawdust" where the vine meets the soil is a sure sign that you have squash vine borers. Once you notice the first "sawdust," it will not be long until the leaves wilt and the vine dies. Standard procedure is to slit the base of the vine with a razor blade and try to extract the borer larvae, but expect reduced vine size and productivity.

Solution: When vines start to run, dust weekly 5 or 6 times with Rotenone/Copper Combo. If borers have already entered the vine, instead of slitting the vine, use a garden syringe to inject Grub-Away Nematodes at 4" intervals over the first 3 ft. of vine, 5,000 nematodes per injection. Adult moths lay eggs from late June to early August; covering with a Super-Light Insect Barrier during this time will significantly reduce borer damage. (Pull back cover to allow for pollination.)

Well, I finally got a picture this morning after hot weather and some rain last night. It actuall looks some better today than Thursday.

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I would trim off all stems except the center. Chack for SVB damage, cut the stem if seen and kill the grubs, and mound dirt around the plant. I have had them recover.

CrAzY LaRrY

The same thing happened to me. It was huge and producing beautifully, and the next day it looked like this. This picture was taken 07/09/2017. Now tonight my second zucchini looks this same way 17 days later! And my one cucumber plant also has leaves that have totally wilted. Last year this also happened to both of my zucchini plants. I'm very frustrated because I take great pride in my garden.

I enjoyed reading all the comments. Tomorrow I will cut it back, check for SVB damage, and mound dirt around it. Maybe it will recover.

Marsha (PA)

wondering if it could also be a vole perhaps?

Could rabbits cause damage like I have?

Sorry to tell you Marsha, but if the plants that just died look as bad as that one in the photo, the odds are way against them living. Perhaps they aren't that far gone?

Depending on where you live, you may have time to plant again. It is getting late in the season though. If it turns out to be SVB, look up some info from a local University. Their websites usually do a good job of giving regional life cycles for when the borers are active. Then, plant some early like you normally do, then, as soon as the SVB egg-laying life cycle passes (or comes close to passing,) plant again. You'll get early zukes from the first planting, and later zukes from the second.

That said... in some southern areas, they have 2 generations, and are tough to beat. There are methods of control, but they do require some time and effort... Bt, needles poked through the stem to kill the larvae, row covers, etc...

No, that type of damage is doubtful to have been cause by rabbits.

Could voles have caused this damage?

Obviously it's not but it looks like mine do after first frost . That's weird .

That happened to both my Zucchini last year- same way, one day beautiful, next dead. Found the dreaded SVB in both. Treating religiously with BT this year- twice a week and after each rain- and so far even though I see the adult SVB flying around, the zucchini are still looking great- and producing well! (Knock on wood!)

I gave up on those kinds of plants and now enjoy shopping at the local organic farmers market. Too much trouble and energy.

PS Voles eat the roots and thus leave the tops dead.

I hope to never have to deal with voles, so I can't really say whether they could be responsible. However, other than SVB, there are a couple of diseases and root problems that can take down plants pretty fast.

ETA: was typing as susan was posting.

Help what is SVB and BT, sorry I'm new to gardening. My plants have a snowy white covering on them.

SVB=squash vine borer
BT=Bacillus thuringiensis (it's a bacteria and is used as a biological pesticide to kill insect larvae)

If the leaves of your plant are "snowy white" then that is likely a fungus called powdery mildew. Nothing said in this thread applies to it.

Rodney