I learned recently that the preplant incorporated (PPI) herbicide ethalfuralin (Sonalan HFP) was labeled for use in hemp and stevia.  See below for the CA/NY supplemental label or download it from your preferred label website.

The use petition was submitted to US-EPA by the IR4 program (see EPA docket EPA-HQ-OPP-2021-0130 at www.regulations.gov if you're into that kind of thing). 

This herbicide is as WSSA Group 3 herbicide that is usually applied to the soil before planting and incorporated into the soil with mechanical methods or irrigation.  After incorporation, the crops can be seeded or transplanted at a sufficient depth that the crop roots grow beyond the treated zone.

Ethalfluralin is pretty widely used in crops like dry pea, dry bean, peanut, safflower sunflower etc. and controls many annual grasses and broadleaf weeds.  Importantly, this the only PPI herbicide registered in hemp or stevia in California so it will undoubtedly be a good addition to the very limited weed control toolbox in those crops.