Rose, I'm am not going to be a great deal of help. I will caution you against giving what may be a sick plant, fertilizer.

Stunting, yellowing -- those are signs of nitrogen deficiency. Deficiencies of other common nutrients may be shown by veining of the leaves and symptoms that add to the mix. Leaf death doesn't come to mind as one of them.

Your ground may have become seriously water-logged and the plants could be showing signs of that. That seems the most likely to me but a problem like that is nearly impossible in the porous soil that I have to garden in. So, I'll go back to that idea that I am not of much help.

Plants have requirements and gardeners often have a strong tendency to try to overcome one problem by fertilizer use. Yes, it can be very helpful - to a growing plant. One that is having trouble with a problem may just be overwhelmed by overfeeding.

Now, perhaps, my response will prompt others to comment from their own, more local, knowledge and experiences.

Steve

Look under the leaves for squash bugs. I've just noticed that I have a ton of these bugs in the last few days. Lots and lots, with lots of eggs too. I've never seen them this bad this early in the season before.