A bit of a cautionary tale here. Don't do this in front of your pets! I gave the cucumber a good coating and then turned my back to go spray down the squash plants, which are in a different garden bed. I glance back toward the cucumber, probably catching the motion of our dog, Duke, moving past. He is standing in the garden. This is something Duke and I fight over all the time, so it took me a moment to realize he is licking the milk off the cucumber leaves and not in the process of digging a hole to lay in. Silly dog.
Here are the results of my using the milk spray just after two days. The leaves even look healthier. Take a look for yourself:
After two applications:
There are still some spots of mildew, but the difference in just two days is amazing! I will probably keep applying the milk mixture for another 3-4 days to make sure the downy mildew is all gone. One down side I noticed was that it seems to attract flies, but my mixture could still be a little strong since I used half and half instead of milk.