In this cool part of the growing season it can be hard to get descent gains late in the season. Cooler weather on a tired plant makes it harder for the pumpkin to get at nutrients. There is something like 200% more biological activity in the soil between 72 degrees and 80 degrees. Cold temps mean the little guys in the soil aren't breaking down as much material and as a result the plant gets less nutrients. Saturday and Sunday we had above average temperatures and it showed on the pumpkin. I wasn't sure if the pumpkin had stopped growing but nearly 8 pounds of growth a day Since Saturday which was a pleasant surprise. I know the tape wasn't lying because it was the first time I had trouble getting between the poles and the pumpkin when I was measuring.
I gave the plant some foliar and drench Neptune's Fish & Seaweed this evening.