Real quick: what is this damage?

I said virus, my buddy said cold damage. It looks like insect damage, but we're very sure there aren't any insects (these plants are pumped full of imidicloprid).
 
Any idea?

What is this damage?

A. Virus
B. Cold damage
C. Insect damage
D. Something else
E. Don't know
 

pest sucking your leaves dry
 
2,4-d
 
little leaf phytoplasma (unlikely)

juanitos said:

pest sucking your leaves dry
 
2,4-d
 
little leaf phytoplasma (unlikely)

Click to expand...

 
2,4-d isn't a terrible hypothesis, the damage looks pretty similar. but risk of exposure is incredibly low, I don't think it could have happened.

You may be dealing with the effects of the imidicloprid treatment. If you google imidicloprid phytotoxicity, you will get many articles on the topic. It depends on your application rate, and the causes are not fully understood, but this might be the culprit.

I've been reading up on this recently because I might be grappling with the same problem. I made a deal with the devil to save my peppers from aphids, and am now paying the price. Good luck with your plant. Here's hoping both yours and mine will make it through the winter.

- Trout

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I am the one growing the plants in the picture. The answer seems to be broad mites (I was able to see the mites on the underside of the leaves but only through a microscope, there was no bronze color in the leaves that most people look for, only curling). 
 
I was terrified that it was a virus (these are some of my breeding lines with very little seed) and even switched potting soils because I was afraid it was a nutrient deficiency.
 
I have come across the same issue every time I try to grow peppers in a windowsill. It seems to be worse with bell peppers than hot peppers but they are on both this time. 
 
The imidacloprid/pyrethrin/neem cocktail I use does not seem to kill the mites. I will probably try soap first and then go to specialty mite killers as insecticides will not touch them.
 
Trout, I would check your plants again (with a microscope or hand lense if you have one) and possibly try to find a broad mite treatment you are comfortable with and see if it helps since it was very difficult to see them at all.
 
I never would have figured this out but I actually found an older post from this forum showing identical damage from the mites and decided to check the leaves just in case.
 
Anyway, hopefully this helps someone since there are tons of pics on the internet of this damage (trust me) and not really many with a confirmed cause.

Window sill ?  Do you get this problem all-year long ?  Perhaps you could reconsider temperature.  Just a thought.
 
If you transplant, then you'll have to wait a pretty long time before the plant get re-established.  So if you're pumping in a systemic and transplanting at the same time, I think there is no way to figure out whats going on.
 
Not saying or denying a mite problem... just looks like temperature to me.
 
Jeff