My 50 day old serrano plant had aphids, and I treated with a soap water mix (1 tbls/1 quart of water). The ants are gone, but the leaves seem to be less healthy (some holes have appeared, and the leaves seem to be thinner). The back of the leaves also seem to be turning black in some places. The fruit seems fine. I water almost daily. Did I use too much soap? Do I water too often? Is there anything I can do to help?
Serrano Pepper Plant
Certified GKH Gardening Expert
If the peppers are fine I would just continue to care for the plants through out the remainder of the growing season.
Yes the soap can cause damage to the leaves and plant. I have found that myself, if the soap is applied in the sunlight it can cause burns on the leaves.
You can apply Neem Oil weekly to make sure the plants stay insect free.
Here are some links with more information.