Q.Some Of My Vegetables Are Turning Yellow Or Drooping, Or Turning Brown And Dying.
Weather has been in 90’s and my garden get sun all day. One of the vines on the cucumber plant turned brown and died after giving the ground a much needed drink.

Certified GKH Gardening Expert
This can happen when trying to compensate for heat by watering. Overwatering will halt root processes and allow for infections to take over, but this can also be a product of Pithium rot and other diseases.
I would apply a fungicide, and keep an eye out for further damage. Here is an article that will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm