Try the site for pumpkins and squash maybe some one there can help you. Past experience tells me they maybe getting wet. Sorry I can't be more help never had it happen.
Go up top to forums and find the site trough there.

My first year I tried Pumpkins, the same thing happened to me. Now I grow pumpkins, squash and zucchini every year and have a lot. I'll tell you everything I found that I did wrong my first year and see how many things you're also doing (these are in order of most significant to least).

1st, I planted the plants way too close together. All of these plants feed *heavily*, more than any plant I know of actually. If they are competing with any other plants, none of them get what they want. At most, I will have 3 (maybe 4 if I did really good soil prep the season prior) plants in a 5x5' area. I start out with 6 plants spread out in the area and then cut out 2-3 that took longer to start about 3 weeks in. That part is difficult to do, but if you know how much it helps them, it makes it easier to do.

2. I wasn't feeding them enough. I feed and water them heavily now. I don't think it's possible to accidentally over-water them, as long as they're getting good sun. I give them fish emulsion almost every day and then start to add a blooming fertilizer (high in phosphorous) once they start growing blooms. Not everyday on the phosphorous fertilizer because I use a chemical fertilizer for that. This applies slightly less to squash and zucchini. I may feed those every 3 days.

3. I didn't prep the area long before planting. I've started prepping the area I plan on planting them the season prior with a good amount of manure. This isn't as important as the others as I've had fine yields without doing it, but it does increase the yield by a good amount.

Oh yeah, one other thing I've started doing since then is mulch. I mulch everything that's in the ground and it seems to help a lot.

This post was edited by iAndy on Fri, May 9, 14 at 21:05

Maybe that's why my zucchini in 100 percent manure recently composted is doing the best. Heavy feeders for sure. The least active is the one grown in potting soil.