Many moons ago, I was a big proponent of a very safe (nontoxic, in fact), yet very effective product called SucraShield. It was a sugar-based chemical (sucrose octanoate esters) - a cleaner, actually - that strips protective layers off of insects and mites, including their eggs and immature stages, resulting in infection, and/or desiccation and/or suffocation and death. The "kill" is almost instant.
Unfortunately, with the passing of the guy owning the technology license and distributing the stuff, it went away.
Fortunately another small company purchased the technology and are now selling it as
OrganiShield, and they reached out to me. I have some pint bottles available, but also managed to get some 2.5 ounce bottles as an introductory offer. One bottle will make 2-2.5 gallons, diluted for application, so that works to the advantage of the smaller grower.