What are they planted in? All I see is straw. Sun? Water? Fertilizer? Need info. Forget about temps.

Good point. They are planted in nice rich garden soil enriched with well rotted compost, pure alfalfa pellets, dried chicken feathers and a little lime to counteract our alkaline soil. It has been hot, sunny, dry and windy here, with low humidities. Sometimes only 3 %. I have kept them well watered.

"a little lime to counteract our alkaline soil" !!!!

I hope you meant acid soil. If your soil is really alkaline and you added lime, you have increased the alkalinity, and that may be the problem.

Actually I meant to say sulfur. Sorry.

Ok now I'm really getting confused. There are no indications of frost damage whatsoever in the photos. The plants are clearly anemic. But given the mixed info given there is no sure way to tell why.

First, why in zone 5 are these tiny young plants already buried in deep mulch. Far too early as the ground hasn't sufficiently warmed up yet, especially for squash, and cool soil temps can cause nutrient uptake problems. Plus you need to pull the mulch back to a 4-6" circle around the plants until they are well established. All that high carbon mulch is further leaching nitrogen from the plants not to mention encouraging pests.

Second, "garden soil enriched with well rotted
compost, pure alfalfa pellets, dried chicken feathers and a little lime
to counteract our alkaline soil" could easily be NOT "rich" soil since there are minimal if any nutrients in it for the plants. Decomposition takes time - lots of time - and is wholly dependent on soil bacteria activity and soil temps.

Third, one should never play around with either lime or sulfa (BIG difference between the two) without absolute knowledge of their soil pH. Doing so only creates further nutrient problems.

Fourth, define "well-watered" please. Unfortunately to many new gardeners that often means daily. Which is usually drowning them.

IMO your plants need to be UN-mulched for a couple of weeks and fed some form of readily available nutrients and your soil needs to be professionally tested so you know what you are actually working with.

Dave

I suspect it's verticillium or bacterial wilt.

Pull the straw back at least a foot for now.

I agree with Wayne, in your Z-5 the soil may still be a bit on the cool side and needs hours of direct sun to warm it up. Constant wind you mentioned can burn the plants too. I mulch my plants once they've established themselves.

btw, at 3% humidity I'd dry up too ;-) but use the finger test to check soil moisture, too much moisture is worse than too little sometimes.

Hi everyone and thanks for your comments. I did look into the wilts and according to my research the squash should not be affected by verticillium (I could be wrong on this) and the plants do not have the symptoms of bacterial wilt. As for the mulch, I have never in my 48 years of gardening mulched so early, and so I agree with everyone on that. What I failed to mention is that we live in a desert, we are suffering the worst drought in living memory and the irrigation water will be scarce to non existent this summer. I am trying to preserve the moisture. The plants are struggling along, and I still really don't know what is wrong. The only idea I have that makes sense is that the searing wind, non-existent humidities, and fierce sun are causing the problem. But I have never had this problem before in this climate, so I am not so sure that is true. I have a soil thermometer and the soil temps have stayed about 60 at night. I am not sure why that would cause the leaves to wilt. The mystery continues. I will let you know how the summer goes. I do have some late germinating squash starts in the greenhouse and will put those out sometime and that may give us some more information. Anyway, there is a good chance that we will not have enough water for the crop anyway this summer, so - we shall see .... and thanks again to everyone for your time...

All other factors aside, having the leaves so close to straw, soil, or anything else, on small plants, can potentially cause issues, especially for transplants. I'm thinking this probably isn't a transplant, though.

Small plants seem to appreciate air, room to spread without touching stuff, clean and clear leaves, and ventilation. They also don't like to be transplanted too deeply (soil near the growth tips can slow or stop growth). I don't think the straw would be a big problem for a larger squash, necessarily, but I wouldn't mulch it with straw, yet, personally. That being said, I haven't used straw for mulch; so, you probably have more experience than me there.