It looks most like damage from caterpillars. There are many species that notch the leaves in this way. They are often very hard to see or they may have departed at this point. The damage is more unsightly than a threat to the plants' overall health. Several sprays are effective, as is hand picking.

I'm not sure what causes it. I have one variety which ALWAYS has some leaves do this, usually early in the season. Then it simply recovers and continues with production. Perhaps someone more knowledgeable will drop by and know what this is. George Tahlequah, OK

My jalapeno plants have leaf damage like that, but they still produced peppers anyway. For some reason it was only the jalapeno plants that got this kind of damage as the other 7 to 8 varieties dont show any signs of this. I didnt use anything to treat them as it didnt seem to be bad enough to be killing the plant.

It doesn't look too serious, I might wash the leaves off with a clean sponge keeping your eyes open for any little pests. I have this look sometimes on a few of my bulbs and if I look closely I can see little spider mites. It won't kill the bulb but you really don't want them jumping to your other bulbs. You can also use dish washing detergent on your sponge, drizzling some down over the bulb. If it persists, you may have to treat with a fungicide of some sort to get it down in the soil which is a whole other can of worms.