Fusarium species recovered from postharvest hemp materials from Kentucky fields

As hemp becomes established as a commodity in the U.S., continued cultivation demands a greater understanding of the pathogens that affect the consumable portions such as flowers and grain. Four Fusarium spp. have been confirmed to cause Fusarium head blight on hemp in Kentucky. Several Fusarium species, including F. graminearum, that are known to produce mycotoxins have been confirmed pathogenic on hemp. Fusarium mycotoxins are regulated in grains used for human and animal consumption. Determining which Fusarium species infect hemp is the first step to producing safe material. While field disease is under investigation, there have been no studies regarding stored hemp. Harvested and stored floral material for production of cannabidiol (CBD) were collected from seven Kentucky producers from 2019 and 2020 harvests. Material was screened using a Fusarium-selective medium and DNA sequencing. At least 12 different species were isolated, most from the Incarnatum-equiseti species complex (75.6%). Species from the Sambucinum (16.3%), Oxysporum (0.8%), Fujikuroi (5.7%), and Solani (1.6%) species complexes were also identified. Additional research is essential to determine whether these Fusarium species are pathogenic or saprophytic, and if they can produce toxins dangerous for humans and animals. Such information is crucial to determine how to store hemp, manage infected material, and promote successful production of hemp products.