If the plants are turning yellow and dying back then the spuds are ready- start the potato salad!

There are early, mid and late season potatoes. And each has a corresponding length of time that the foliage stays green before naturally browning and signaling digging time. Withering at this time of year is probably normal. But if your leaf edges are crispy brown while the rest of the same leaves are green, that most likely means water stress. All is not lost, you'll just have smaller potatoes and/or less of them. I wouldn't try to nurse the plants on. They already seem to have decided to shut down. You might want to test a few potatoes when you dig them. There is wisdom in letting them cure in the soil for a week or two to "harden up" the skin. That doesn't make the skin tough and displeasing to the palate, but it does help the potato resist rotting in storage.

Rick

My guess is that your potatoes are ready too. The first year I planted a vegetable garden I thought my potatoes were dead too. Boy am I happy I am not the only one who thought that!

Can't tell you how much I appreciate this forum. It has really helped us. The grapes I planted last year, with your guidance, have flourished this summer and are now climbing the frame and are 4' high. They do not have grapes on them and probably won't this year, but next year I might actually get a grape or two.
I have TWO apples this year. What a miracle!!
Thanks again.

No matter what the stage of our individual horticultural development, we all benefit from the exchanges here.
Rick