Remove the foliage that is most heavily infected. How much to remove is up to you. Once a leaf has powdery mildew, that leaf is unlikely to recover so you might as well remove it.

There's a couple of organic sprays you can use to treat the rest of the plant. They may or may not work. Often, when your plant gets powdery mildew, nothing you do will really stop it, but often you can slow it down enough that you're able to get a harvest.

Milk sprays---mix one part milk to 9 parts water and spray the foliage. This is best done early in the day so the plant foliage dries before nightfall. Having foliage that stays wet all night is part of the problem. As much rain and dew as there has been lately in many parts of the state, I imagine powdery mildew is becoming a problem in some places.

Baking Soda spray---1 tablespoon of baking soda in one gallon of water. If you have a summer-weight horticultural oil you can add a couple of tablespoons of it to the spray to help the spray adhere to the foliage when you spray, or you can add a few drops of soap (not detergent....and many dishwashing liquids are detergent, they are not soap) like Dr. Bronner's castile liquid soap or Murphy's Oil Soap, Fels Naptha soap or insecticidal soap to serve as a spreader-sticker. Spray in the morning so the foliage is dry before nightfall.

There are some commercially-produced sodium bicarbonate sprays that are available and some people feel they are a little better than the home-made baking soda sprays. The one I use is called GreenCure.

Neem oil also can be used as a fungicide but check the label of the neem oil product you have to make sure it is labeled for use on cucumbers.

Cultural controls include watering the soil at the base of the plant with a soaker hose or drip irrigation as opposed to watering with a sprinkler, avoiding planting too many plants too closely together because that impedes proper air flow, and avoiding the use of quick-release nitrogen fertilizers which can cause excessive foliar growth with also impedes air flow. However, even when you do all the above, your plants still can get PM because it is just so common some years.

In the future, select cucumber varieties that are tolerant of/resistant to powdery mildew. There are lots of them available, both for slicing or for pickling. However, nothing is 100% resistant to or tolerant of PM, so even growing varieties with a high level of tolerance doesn't mean you'll never see PM.

Hope this helps.

Dawn

Thanks. I'll give some of them a try.