I would want to know if I definitely had mites before spraying with any dangerous chemical. Perhaps you have a lens or access to a lab that can confirm mites?
I have sprayed with Kelthane years ago when it was still available. I forget the dosage. . . perhaps 1 tsp to a gallon. One spraying isn't enough to kill the eggs; I think the advise is to spray three times about a week apart. Kelthane is reported to have a short shelf life of about two or three years.
Kelthane worked on my plants for awhile but never seemed to kill all the mites. . . perhaps it was old or I didn't spray for as long as needed.
Even if Kelthane were still available, I would not use it now because Forbid is a much better choice. A one time use of it took care of my problem.

Terri

I had a similar issue, and ended up buying Avid. The instructions I was given by other AV growers was to make a bucket of the stuff and with disposable dish-gloves, dunk the entire plant (rootball and all) in the bucket. Then repeat in 2 weeks. Right after the first treatment, the stunted/crowed top of the crown started growing again almost immediately (so I'm guessing it was mites or something along those lines).