I'm suffering from a mild issue of the same thing, SPIDER-MITES. Alcohol and water 50/50.
Akumasensei85 Reviewed by Akumasensei85 on . Plant infestation & hard black spots (w pics) Aloha! I am growing, as a first time caregiver, three plants on my balcony in Hawaii. Two of the plants have been harvested. While I was trimming the leaves off of the third for harvest, I noticed several problems. 1. Black hard spots that are on the stem and leaves. 2. an infestation of some kind of bug. 3. the plants leaves have been yellowing for quite some time. I was told this is normal, but that's obviously a lie. Rating: 5