Weeds
Hemp is not very competitive with weeds in the first 3-4 weeks of growth. Once canopy closure occurs, hemp can shade out smaller weeds. However, hemp grown for grain or cannabinoids is planted at a lower density per acre compared to fiber hemp and canopy closure may not occur or take longer.
Weed control is one of the largest issues in hemp production. There is now one Section 3 herbicide (Sonalan HFP) registered for use on hemp in the United States. The supplemental label for the product can be found here. Herbicide screening is underway at universities across the county, including Purdue and Vincennes University.
Choosing field sites with low weed pressure to begin with, is the best preventative measure to reduce weed competition. Rotating after crops where you can use conventional weed management may be an option, just be aware that limited research has been done on herbicide rotation restrictions in hemp. Create a weed management plan before you plant your seeds!
Growers are using various methods for weed suppression and control including; pre-plant cultivation, in-row cultivation, and mowing. Weeding equipment used in organic systems is also an option. In CBD hemp, plastic mulch is one method of weed suppression. Some growers also use cover crops for weed suppression. The cover crops may be terminated before planting or left to live between the rows of hemp.