Premature pumpkin harvest here. Heard a large crack in the back yard yesterday, and went outside to find my largest Big Max lying on the patio with a big gouge out of it. Either it got too heavy for the stem to support or the squirrels were playing with it. Anyway, it broke off and rolled down a slight slope and over the retaining wall fence. Decided it was nature's way of telling me to harvest and get the vine into the compost pile. The big pumpkin weighs 43.5 pounds and has a 54 " circumference. The smaller one is only 13.3 pounds with a 31" circumference. Loved growing these this year and will probably grow them again next year. 3 New England Pie pumpkin plants have produced 5 good sized pumpkins and I have 6 more that should be ready in a few weeks!

once you reach about halfway through the season, leaf growth becomes a diminishing returns thing as the plant puts its energy into fruit. Highly infected (yellowing) leaves are doomed already so it's best to cust them off. If you have any leaves at all there is always hope. Just try to contain the damage and possibly use a fungicide if you're desperate.

You will get bigger better pumpkins if you prevent powdery mildew so the vine can photosynthesize to its maximum potential. Since it already has spread substantially and probably has spores on all of your leaves, you might as well just let it take it's course, but next year use a sulfur based fungicide in powder or liquid form (I prefer mixing powder with water because the liquid is so expensive and use it so fast and powder is hard to apply). Leaving the PM is like letting a cloud cover set in until it is so thick that it is like night time all the time and the leaf is useless or negatively hurting the plant by consuming extra nutrients to feed the parasite.

The angular splotching in the vein intersections is a naturally occurring anomoly. It's absolutely nothing to worry about and shouldn't be treated. That is very different than what we see in the original image, which does appear to be PM, at least in your picture. Maybe it's all normal cucurbit splotching. I've attached a link to Google images of white splotches. Some show PM and others are of the other markings. You may have to decide for yourself. I've never used worm tea, milk, or baking soda. My preventative treatments always include good spacing between plants, conservative fertilization practices, rinsing of foliage with plain water, neem applications. Be sure to collect and dispose of infected foliage. Kimmsr has always recommended the milk or baking soda and many report success with it. Worthy of a try if you think your plants have PM. Here is a link that might be useful: splotches