My first recommendation is to stop watering them and to stop feeding them. Peppers need to dry out between waterings, and just because the main roots look relatively healthy doesn't mean the feeder tendrils you can't easily see are healthy. If you're keeping the soil moist 24/7 you're doing more harm than good.

Also, they don't need constant feeding. You are probably building up to much fertilizer in the soil unless you are thoroughly flushing the soil out every time you do it. If you are going to fertilize, go with half of the recommended amount for containers, and do it every third or fourth watering (which you should only be watering once every 1-2 weeks, so only giving it a mild feeding every month or so).

Your photos are not good enough to know for sure, but you might look up Pepper Mild Mottle Virus and see if the symptoms appear to be the same.

DarJones

That fertilizer is inappropriate for plants.

Plants never use that much P (middle number). So it could very well be a salt issue.

Josh

Thanks for the help all!

I had the hunch it was more likely a moisture/fertilizer problem, but each of my plants somewhat resembled the symptoms of disease, and upon inspecting a few of my other nearby plants I could see faint signs of chlorosis on the leaves (these haven't been fertilized in weeks and have just the right amt of moisture).

So rather than risk a possible disease in my plants/soil for next season, I figured better to be safe than sorry. I took out all suspicious plants and will be treating the soil for the next couple months just to be safe.

Thanks once again!