I just dealt with a huge infestation of Russet Mites in my commercial grow. The only thing that was able to really kill them has been Sulfur mixed with DE. There is simply no combination that will work as well as this. I have used everything mentioned above and I repeat nothing worked as well as this.
Stop feeding your plants for a week because the Russet Mites feed off Nitrogen. Mix Sulfur (2 tablespoon per gallon) with DE (pour enough DE that will make your mix a milky consistency) I used soap as a wetting agent - APPLY AS A FOLIAR SPRAY. The DE works after it is dry, the sulfur works on impact. Repeat this spray every two-three days. The results will be immaculate.
Keep in mind that this cannot be applied if you have sprayed any type of oil. In the case, that you have sprayed something with oil, such as Mantis, you will have to wait two weeks to spray this