When you say round and fat, do you mean they are not forming into longer, even shaped fruit but are tapered at the end? This is a potash deficiency and often happens toward the end of the season when growing cucurbits. Sounds like the nights may be cooling down a bit and the days getting a bit shorter ladybug? Once it slows down enough there will be few or no embryo fruit forming on the cucumber vine. You can call it quits anytime you like, but i tend to just rip them out so i can start preparing the bed for the next crop. The vine put thru the lawnmower is great for a compost additive. Maybe it's time for some peas or beans to go in where you are? Till the soil, apply some lime or dolomite and maybe fertilise and get it producing again is my suggestion. The tomatoes being slow to ripen also suggests the season is slowing. Even though i'm sure the days are still hot. Say goodbye to summer. She's on her way out.

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The secret is the soil.