Looks like it could be anthracnose,  it should necessarily kill the plant but it will definitely stunt the growth.

More info:  Zone 8 South Carolina.

Potatoes have been in the ground since late February.  They started to look a bit bad after it started getting hotter and I didn't up the watering as much as needed, but have looked progressively worse.  The brown patches concern me.

My potatoes are looking like crap. I didn't notice any flowers yet. Are they diseased or just not liking the 95F+ weather?