Potted Cucumber Leaf Problem
The attached photos are of leaves on a potted cucumber plant on a back deck. The leaves start turning on the older plants first. The plant is still producing cucumbers. Your help in identifying what is happening with the plant would be appreciated.
It is hard to identify a particular disease based on these pictures. The leaves are too far gone. It is best to observe leaves in the early stages of the disease. It may be possible to send them to the diagnostic clinic for identification (https://pestid.msu.edu/submit-samples/). This is the time of year when it is difficult for homeowners to keep cucumbers and other vine crops alive. Downy mildew has shown up in the state and it is a devastating disease on many vine crops, cucumbers in particular. I do not believe that is what your plants have, but they will have it soon and there is nothing homeowners can do for it. More information can be found at https://veggies.msu.edu/downy-mildew-news/.