This is in south India. I purchased a Tulsi plant around 3 months ago from a local seller who told me he also had medicines for plants if I ever needed them. I asked what medicine, and he didn't know. Approximately two weeks after bringing the plant home, there were some dark brown bugs crawling all over it and the leaves appeared to have powdery mildew. I sprayed a milk+water solution under bright sunlight for three days and the plant actually recovered. I also pruned off many leaves that had no chance of recovery. In a few days it sprouted fresh leaves all over.
However, a week or two later, I noticed very tiny red bugs (size around a quarter of a millimeter) crawling all over the leaves of the plant. This time, there also seemed to be some kind of tiny webs all over the stalks of the leaves. Leaves began turning brown, had some kind of white powdery substance on it and although the plant was constantly sprouting fresh leaves, the bugs and the 'disease' always caught up and devoured the leaves. The plant has and still is able to sprout fresh leaves though. The bugs seemed more abundant and visibly there during the rainy days. Now that the rain is gone, I don't see bugs, but the tiny brown blobs on the leaves shown in the first picture just might be them. I heard Tulsi needs direct sunlight, so it has been kept on a terrace where it gets morning and afternoon sunlight in plenty.
I don't want to go to the seller because I believe they may be running a scam where they sell plants which are already sick/disease-prone so that they can sell 'medicine' when gullible customers come back.
1. Could anyone help identify what is wrong with the plant and how to fix it?
2. The plant has dropped seeds all around it. Would it be more advisable to kill the plant and grow saplings from the seeds? Or would they be prone to the same disease?
3. Does anyone know of any supposed chemical that such suspected scamsters could use to make plants seem healthy only as long as the chemical is used?