All of our pumpkin plants came down with an illness, and when researching this issue we discovered it’s called powdery mildew. With more research it looks like we won’t want to eat the pumpkins that this has affected, and it’s caused by the partially shaded location and crowding of the pumpkin plants.
There are of course chemicals that can help treat the problem, but I never like to go that route, so we searched for an organic solution. Several sites noted that baking soda in water, used with something to make it stick such as dish soap, could help. The best info we found was at this site: Growing a Greener World
So I mixed up some of the solution for the girls and they attacked the disease. It seems to be helping, and we’ll keep applying it until the pumpkins ripen enough to at least be used as decoration.