Kay Lancaster wrote:
Is the weed you're trying to control annual or perennial? If it's an
annual, I'd just dig the bed over now and in the spring, then use a light-
occlusive mulch when you plant your pumpkin seeds. Cardboard is great
for this; it's a nice clean mulch, so helps control some soil borne diseases,
helps keep the soil moisture even, and you can dig it in next fall with
no muss, fuss or bother. g

The weed in question is almost certainly Japanese stiltgrass
(Microstegium vimineum). It's an annual. Using a layer of mulch
around the pumpkin plants will minimize the germination of the
stiltgrass seeds, and any seedlings that do appear are very easy to
weed out, due to the weak roots.

Cutting the existing stiltgrass now will prevent it setting seed.
Repeat the mulching, weeding, and late season cutting for several years
to get rid of dormant seeds in the soil.