What is ailing my cucumbers and tomatoes?
It looks like your cucumber could have downy mildew. Here is a link that explains it and what you can do. http://www.extension.umn.edu/garden/yard-garden/vegetables/diseases-of-cucurbits/downy-mildew/ . The tomato may have septoria leaf spot. Here is a link that explains that. http://www.extension.umn.edu/garden/yard-garden/vegetables/septoria-leaf-spot-of-tomato/ . Both problems are worse during wet, humid weather. Good air circulation and not watering plants late in the day can help some. Cleaning up all plant material is also helpful.