Well, at this pont in time it will not make much difference anyway. The pumpkins/gourds/squash season is almost over.
Or at least how it is here at zone 8 GA. We are having night lows of around 45F.

What you have described is "Powder Mildew", which is fungus.
You are lucky that did not get it earlier. A lot of pumpkins become suseptible to this disease whe they get old. By now probably your pumpkins are fully grown and will need minimal help from the mother vine.
I do not have pumpkins but I do have quite a bit of gourds.
Most of the vines are either dead or dying.

Mine got hit with the mildew a week or so ago too.. My vines were already starting to dry on their own though so it was fine.. Just be sure not to till your vines under this year as I've heard the mildew will live in the soil then.. I pulled all of mine and tossed them into the garbage.

Also, once your pumpkins start to turn orange at the base, you can go ahead and pick them as they will continue to ripen off the vine.

Thanks for the info guys. I discovered that I'm not in zone 8b (asked the local nurseryman.) I'm actually in zone 3b-4. They use the Sunset Garden Book to determine that. Just clearing that up first. I will change my profile directly.

As for the pumpkins. I never got any on my vines. I think I may have planted too late in the season as the vines just started to really take off last month. I talked with my neighbors who grew gardens this year too, and they said they got powdery mildew on some of their vegetables too. Hmmm... Anyway thanks for getting back to me :)