Powdery mildew looks kind of like someone has dusted a bit of talcum powder or flour on plant leaves, when it appears. Most often it wipes off quite easily, as well.

Here is a link that might be useful: About Powdery Mildew

I usually think of PM as growing on the top of the leaves, not the bottom. But it can start out looking just like that. Your picture isn't sharp enough to be certain, though.

I usually think of PM as growing on the top of the leaves, not the bottom. But it can start out looking just like that. Your picture isn't sharp enough to be certain, though.

Here is another photo of a more infected leaf. I am getting sick of having to prune off heaps of leaves every day. Does the milk remedy really work?

This post was edited by Bendyrulz on Fri, Jan 2, 15 at 1:55

I have had good results controlling Powdery Mildew with a 50/50 spray of fat free milk and water. I have also had good results with a mixture of 1 teaspoon of baking soda in 1 quart of water.

Does anyone know if worm tea is a good cure/prevention of powdery mildew?

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

I am having problems with new pumpkins turning yellow and dying. Only one out of dozens has managed to survive past that stage.

A plants leaves that turn yellow is known as Chlorosis and has numerous causes. The link below is a good resource about this.

Here is a link that might be useful: About Plant Chlorosis

The leaves aren't turning yellow; the actual fruits that are forming are turning yellow then dying.