This is happening to my potatoes also. Really weird. Usually it's just one sprout of the plant. I've had a lot more rain this year than usual, and I'm wondering if the soil is too soggy for them.

I may have found the problem, but I have no idea of the cure. Today I pulled the wilting plants and happened to notice some white worms about 3/8 to 1/2 inch long and about 1/16 inch in diameter crawling around stem at the point it had been in the ground. On two of the stems I discovered a hole below ground level and when I slit open the stem, the whole inside had been eaten out and was occupied by these worms. I'm going to try to take a picture to post, but they are so small.

European corn borer? Despite the name, they do infect potatoes as well, usually by burrowing into the stems, as you mentioned. I'm not sure if it is or not based on the size measurements you gave. Take a look online to see if the pictures match up to what you've got.

How big is the hole below ground level? Sounds like gophers to me.

Nope. Not gophers. I should have made it more clear that the hole was in the stem at a point that would have been under the ground. The hole in the stem was about 1/8 to 1/4 inches in diameter. Unforunately, by the time I had charged the battery to my camera, the worms were gone, so I have no picture.

After re-reading, it is fairly clear. I just have gophers on the brain. I have so many of them.

--McKenzie

I guess that I'll never know what the worms were. They were nowhere near as big as any corn borer that I have ever seen. They were about the size of 1/4" to 3/8" long pieces of spaghetti and they were white. I guess that it could have been the larvae of some moth.

None of the other vines seem to be affected, so maybe I should just count my blessings. I'm just wondering, though, if there's some type of prophalactic treatment that could be given to the rest. What do you do for vine boring pests?

Spinosad has worked for me with various borers (including squash vine borer), in conjunction with digging as many as possible out of the vine with a bent pin.

Spray spinosad in early morning or late evening, as it can do harm to day-flying beneficials as well as the baddies.