Sorry about the squash. I just read in Why Line the Bottom of the Bed (a couple of postings down) that your problem might be SVB. Never seen one myself, but it's worth checking out. I don't know that much about gardening, and even less about computers or I'd give you some links!
Good luck!
h.

Some good links for Squash Vine Borer (SVB) here...

Here is a link that might be useful: RE: SVB Questions

I just discovered that I have the same problem with my yellow squash, zucchini, and cucumbers. The yellow squash is dead, the zucchini is hanging on, and the cuke vines are growing strong (for now). I found one yellow squash and one small cucumber with white worms feasting away. I also found a black moth on one of the stems. It's definitely the squash vine borer.

I lined the bottom of my boxes, used Mel's mix recipe (1/3 vermiculite, 1/3 peat moss, 1/3 of five kinds of compost), and had the plants growing on trellis netting. I even grew nasturtiums in an adjacent box (although they didn't do so well either.) The location did not even have a garden previously, just some dirt in the shadow of overgrown forsythia and tree roots.

I've read that the SVB comes from the soil below. Would they be in soil where there were no squash--or even any vegetable plants--previously? Would they come through weed block fabric?

I had SVB last year first in my zucchini & then in my summer squash. There is very little you can do, but you can cover the trunk of the plant with nylon or provide some other barrier, but not much works besides trying to kill the larvae/cocoons in the ground over the winter by turning the ground in your garden.

CloneZero

I have a question in re: these ..... if it says the spacing is "3 feet" on zucch & squash .... do I still put them in a single square foot?

Soupaman, I use a single square foot for my squash and zuchinni. If it is a vining variety, then I use a vertical square. If it is a bush variety then I to use an outside corner square and let it grow out over the walk area. In the adjacent squares I plant leaf lettuce or something else that would appreciate some shade in the summer. Another option is to make sure that what you plant in the adjacent squares will be harvested or ready to harvest by the time the squash grows large.

Normally I only plant one squash plant per bed since each plant can be very large. However, one year I was trying several varieties of squash to see which ones I liked best. I had squash growing in all four corners of a 4x8 bed as well as a couple in squares on the long sides. I planted most of the squares adjacent to the squash with bush beans. The beans kept producing even though they were partly covered by the squash leaves. That bed was a green jungle but very productive. I would hunt each morning for squash flowers to pollinate and squash to harvest; I would also search under the leaves to remove the reddish eggs of the squash vine borer. Each day after work I would search for green beans to harvest. That year we had squash and green beans nearly every day during the harvest season, dried squash chips as snacks, and the green beans I blanched and froze lasted until December.

I suppose you could plant the squash in the center of a 2x2 area but I have never found that necessary in order to get more squash than I and my family need. I still had plenty to give away, especially during the year of the variety trials.

Since I searched daily under the leaves for SVB eggs, I had very few of the larvae get into the vines. When one did, I dug it out. Occasionally I needed to slit the vine. When I do, I used twist ties to hold the vine closed.

Anna

I grow my squash as 3 vines from each corner square on the south end of a 4' bed (none of my beds are square) with a 3x'4'chunk of bed area reserved for them, plus knowing they will spill over the sides (so similar to Anna's idea of letting as much as possible spill out to preserve bed space).

I save up my paper towel and toilet paper rolls every year.
Cut them about 4 inches high.
I put the collars in 2 inches underground and leave 2 inches above plant the zuch or yellow squash seed in the roll. No vine borers here for 3 years using this.