I believe we have a case of powdery mildew on our cucumber plants. I suspect we planted them too close together and shouldn't have watered in the evening. The leaves are covered, then yellow and die off. Is there anything we can do to save the harvest? Anything we can use on the neighboring squash plants, which are also starting to get spots on the leaves now?

Heather, soudns like powdery mildew. You can use sprays of Remedy a bicarbonate of soda product or products containing benomyl, chlorothalanil or copper.