Environmental stress. perhaps high light and winds.

I would have said "COOL" weather. But your temps look ok. In this case it is probably nutrients deficiency. Looks like Phosphorus deficiency. Have you been fertilizing them ? what kind of fertilizer you are using ? Does it have "S"ulfur and Magnesium ? Epsom salt can provide both of those. Have you heard the "match trick" ?
Just throwing 0.02 in the hat.

Is that CLEAR plastic? Do you use it every year with no problems? Looks awfully reflective. I'd go with jean001's assessment. Did you spray anything recently also?

Kevin

soil test in late winter revealed low phosphorus. I used recommended 2-4-0 fish/kelp fertilizer in liquid form through drip tape when transplanting. The only other deficiency noted was Boron, but I have been afraid to add any. I did add purchased compost when transplanting as well. The soil has a lot of clay and the field was previously in second year of commercial tomato four year rotation (last had soybeans, fallow over winter, rototilled this spring). I do have a wind problem and have kept covers over the peppers when needed.

Since they were covered my guess is sun burn. I would keep them watered when needed, and fertilize with a liquid fertilizer as per label directions indicate.

Should I separate the two plants growing in the nursery pot? I will be using 5 gallon buckets and want to know if I should only put one plant in each bucket.

purpldoll6x: Yes, separate. Do you know how?

Btw, I see those are bells. From my experiences, I don't think large fruited annuums like bells do well in smallish containers. I've done pretty good with chinense varieties in 5 gal, but my Anaheims et al don't do as well. They're fine for 1 flush of fruit. After that, the fruit suffer. I'm switching to 10 and 15 gal for those varieties.

Kevin

purpldoll6x - Agree that you should separate, and I think you should give the 5 gallon buckets a shot with one plant per. I grew a couple Carmen peppers in 3.5 gallon containers last year and they far out-produced those planted in the garden bed. Your Orange Bells may perform differently, but if you've already bought the containers and the plant(s), I say go for it. Then take good notes and decide if you need to make changes next year. Good luck!

Thanks so much woohooman and Kathyb. I'm not sure how to separate them but I will research it first. I'll cross my fingers and take notes.

Please do not hijack the thread. The leaves look dead between the veins . I would think it is K deficient.

Update: the peppers from my original post responded well to warmer weather. Fertilized with 2-3-0. Plant growth appear somewhat stunted but they are now fruiting.