Answer: There is a fungal disease called black fruit rot that attacks pumpkins, winter squash and gourds. It starts as irregular circular spots that are light green or yellow, then turn gray, then brown, and finally black. This leaves the fruit vulnerable to attack by other rot-causing fungi and bacteria. I recommend that you destroy all plant parts by burning, or burying them in an area away from the garden, since the fungal spores overwinter on plant parts. If you can, plant your vining crops in a different area next spring.
In general, if fruit are in contact with soil, they're more succeptible to attack by insects and disease organisms. I have seen this happen to some my own winter squash, melons, etc. The constant exposture to moist soil makes the fruit a haven for fungi, and as their growth softens the rind of the fruit, insects (wireworms, beetles, etc.) can easily invade. Where insects burrow, the fruit exudes sap or juice, and makes it a friendly place for even more microbes! Lucky them!
The best solution to this problem is to plant your vining crops on sturdy trellises. As the fruit enlarge, attach "slings" to the trellis to support each one, using nylon pantyhose or other stretchy, strong fabric. Some gardeners use hogwire, cut and formed into an arch on the soil surface like a tunnel, over which to train their vining crops. This keeps the foliage and fruit off the soil, away from moisture and and many insects. I wish you the best of luck for next year!
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