gingivitis?
j/p
I do not know the answer, but I had a few plants all from the same parent seed stock and one of them required (not desired, but would have died otherwise) more N. Now, I am definitely not saying you need more N, just that this one plant may have different needs than the rest and the uniform treatment may have been the direct cause - All hypothetical or course.
But you may want to experiment with a very small increase in specific nutes. Emphasize
small increases. I would start with cal mag, though I do not think that is specifically the issue, you need to start somewhere (if you can't get a better answer than this one) and cal mag is not gonna kill the plant if you have a little too much.
You could always start over with that one by flushing the soil out and enacting a totally new fert method.
Just a few ideas for thought, sorry I don't have a direct answer.
Also, keep in mind that the leaves that are already affected are not likely to ever fix themselves. The new growth will tell you if what you are doing is right or wrong. Of course, if the old growth dies off, then something may be off. The old growth may never be normal again, but it should live.
PS: every one of my pepper plants that has had that kind of curl for me has eventually grown out of it seemingly on their own. Maybe I did something without knowing it.... was not a controlled experiment, so can't be sure.
