Agronomic Practices Regarding Industrial Hemp Production for Cannabinoids: A Pilot Study in Florida.

Industrial hemp (Cannabis Sativa L.) is a versatile crop and shares its botanical name with marijuana. Legalization of industrial hemp production in the United States arrived with the new Farm Bill in late 2018 at the federal level. However, very little information is available about growing the crop domestically, especially for cannabinoids production. To evaluate industrial hemp varieties and management practices that are suitable for cannabinoids production in Florida, a pilot project was initiated by University of Florida. Both field and greenhouse trials were performed. Preliminary results indicate that the day-length sensitive varieties (Cherry Blossom, Cherry*T1, and Cherry Wine) had superior flower yield and CBD content than the day-length neutral varieties (KayaGene 9201 and 9202), but the day-length neutral varieties can be potentially used for double cropping. Pinching the top 2-3 nodes when plants are young may not increase flower yield or cannabinoids content. Flower yield gradually increased with increasing plant density, but cannabinoids content was not significantly affected. The development of CBD and THC content in flowers synchronized during the growing season, therefore growers need to be cautious to avoid above-threshold THC content. Bromoxynil seems to be a safe post-emergence herbicide for industrial hemp, while halosulduron and metribuzin both caused substantial phytotoxicity.