Author: Nicole Gauthier
Planning Unit: Plant Pathology
Major Program: Hemp
Outcome: Initial Outcome
Since hemp was reintroduced in the U.S. under the 2014 Farm Bill, acreage in Kentucky increased dramatically with a peak in 2019 to about 26,500 acres, the second highest acreage in the U.S. Approximately 100,000 acres were planted in the southeastern U.S. and over 500,000 acres in 47 states across the U.S.
Hemp is susceptible to a wide range of diseases, including over 25 leaf spots, root rots, and head & flower molds. In 2019, two cases of Fusarium bud and flower blight (FBB) were confirmed in Kentucky, and in 2020, seven additional cases were confirmed. The causal agent of FBB in hemp, Fusarium graminearum sensu stricto, which is well known as head blight and head scab in wheat and corn. Fusarium graminearum is primarily a flower pathogen; it infects flowers and accessory tissues, often moving to contaminate seeds. The fungus produces harmful trichothecene mycotoxins including deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEA). DON causes digestive disorders, oxidative damage, and reproductive toxicities, affects cell and organ functions and viability, and inhibits the immune system. It is regarded as a teratogen, neurotoxin, and immunosuppressant by the WHO. Less common NIV causes digestive and immunological problems, and ZEA causes disorders of the hormonal system and diseases of the reproductive system. Mycotoxins in harvested grains are monitored worldwide to protect human and animal health. However, no testing protocols or tolerance levels are set for hemp.
Traditional and digital resources, including email alerts and webinars/recordings were developed in order to educate hemp growers of potential risks and disease prevention methods. Beginning in 2021, UK hemp pathology team began testing field and stored hemp for identification of Fusarium graminearum and other Fusarium spp. Research regarding production of mycotoxins on hemp is ongoing.
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