My zucchini plants are, possibly, in peril, and if anyone can help (I'll explain below), it would be greatly appreciated.

Onto the problems. I have four zucchini plants, two plantings of two plants each (two plants come in each pot from the store, so I don't bother separating them). The first two plants ("Ball's Zucchini") have, just this last day or so, had problems with their leaves. The edges seem to be dying. The two picture below show this. This isn't normal heat-induced wilt, of course, because the leaves would just spring back. This wilt is softer, like it's deader-than-dead, and curls up. It is soft and is not brittle. I checked the undersides of the leaves and, though a little messy with dirt, don't have any bugs or eggs that I could notice, same for the base of the plant. Otherwise the leaves are fine and green. Also, this is happening to older leaves (the oldest are dead as usual) and even to new leaves (little wilting at the edges). So, please take a look at the two pictures below and tell me what you think. I've looked at tons of pictures and discussions online and can't seem to find anything like mine. All the forms of wilt are either colorful (brown or white spots along with the wilt) or much more extreme in their destruction. Water has been fairly normal. There was a little hail, which punctured a few holes in the leaves, but nothing big. And they've been in the ground a month. Today was, however, much hotter (32 above) than yesterday (25 above). Could maybe the edges of the leaves have scorched under the intense heat before they could wilt like normal and have been killed? I'll take that over bugs.

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The second set of zucchini plants are long yellow ones (no fruit yet). The plant is small (but so was the plant in the pot) and has little yellow spots on the leaves (as the pictures show). Yet, all the new leaves look nice and green so far. The above plant worries me, while this plant below is just questionable. But, since I've seen some leaf issues that produce yellow spots, I figured it would be prudent to check with everyone here in case there is a problem so I can head it off before it gets too severe. Oh yeah, and no bugs or eggs that I could see on this plant either. There are red ants in the garden, but they've been there a long time and haven't hurt anything else.

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Thanks everyone for the very helpful comments to come. If the plants wilt more, turn color, or burst into flames, I will post an appropriately frantic update.

John