Answer: Your plants might be suffering the early stages of a disease, but my suspicion is that they are suffering water stress. Cucumbers are mostly water and the vines will stop producing unless they receive an adequate and steady supply of moisture. They also require a rich soil for optimum performance. You might consider side dressing them with some compost or a balanced fertilizer, along with ensuring they receive a deep soaking at least once a week.
Good luck with your crop!
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