I haven't been able to spot any bugs on the plant, though I might need to get a magnifying glass out for this one.. Otherwise I think calcium is a good place to start.

I can almost guarantee you have a broad mite problem. Get some cold pressed neem oil or pyrethrin.

Thank you Brennan! After a bit of research, it seems broad mite is a fairly common pest of chillis. Do you think White oil would also work?

My advice for the future: never buy unhealthy looking plants. In the long run they could prove to be quite costly.

Danny

not familiar with white oil, but neem has a compound called azadirachtin that interferes with their eating and reproduction whereas most oil based insecticides only kill soft bodied insects by clogging their pores. Make sure it is cold pressed neem and not hydrophobic extract of neem, as only cold pressed has azadirachtin.

Thanks Brennan, I've already tried white oil but it's been raining constantly ever since I applied it. When the weather clears up I'll give the neem oil a shot. How long do you think it should take to see the effects of the oil?

Some effect will be seen withing a da but my experience is that it takes a couple weeks to clear all the way up. When I say clear up I am talking about the pests, the deformed leaves will stay that way. New growth should be fine.

If it is Broad Mites the problem will take much longer to be remedied. First, they typically target feeding on the flowers and a drenching spray is needed to contact them. Second, since they feed on flowers the biggest problem is the damaged fruits. Fruits will be deformed and scabby. First signs of fruit damage may be many weeks away.

But don’t get overlying convinced that you have Broad Mite damage. The damaged plants can be any number of things including herbicide injury or a virus disease. You need more professional help to identify the problem.

I had this same problem awhile back, which many fellow members chimed in on. Although we didn't really find a solution or the cause, for that matter, there were a lot of good ideas.

For what it's worth, if I recall correctly, I always have at least one or a few pepper plants (of any variety, no consistency in variety) that does this every year for reasons I've never been able to pin down. While I do tend to experiment with this or that, all of the plants use the same soil each year and many times, the exact same style/size of pot and/or ground, too.

[Wrinkled Leaves Thread[(https://www.houzz.com/discussions/yearly-issue-with-only-a-couple-of-my-peppers-dsvw-vd~3279243)

Mine lasted one bout, got about 8 chillies off 2 plants but then they just well appeared to die and harden, I snipped it and wood/ stem was dead and hollow though there's still roots strongly in the pot, dump it or something?