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Author ORCID Identifier

0009-0004-8992-0088 

Date Available

4-24-2026

Year of Publication

2026

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Agriculture, Food and Environment

Department/School/Program

Plant Pathology

Faculty

Nicole Gauthier

Abstract

Hemp was reintroduced as a commercial crop in 2018 after a near 50-year production ban under the Controlled Substances Act. Since reintroduction, Kentucky has consistently ranked among the top five hemp producing states in the US. Surveys have shown that hemp is susceptible to a multitude of diseases that impact production. Among the most concerning diseases in Kentucky is Fusarium head blight (FHB). FHB is a major disease of cereals that is caused by various Fusarium species, predominately F. graminearum. FHB of hemp caused by F. graminearum was first reported in Kentucky in 2020. A survey of 25 different Kentucky hemp production fields was conducted in 2022 and demonstrated that F. graminearum infection was widespread across the state.  F. graminearum isolates were then collected from symptomatic wheat across Kentucky and compared to isolates of F. graminearum collected from hemp in a variety of traits, including fungicide sensitivity, pathogenicity, growth rate, and mycotoxin production. No significant differences in F. graminearum populations from hemp and wheat were observed,and cross infection ability was confirmed; this suggested the potential for enhanced inoculum buildup in hemp and wheat crop rotations. To investigate the impact of crop rotation on FHB of hemp, a two-year field trial was conducted at University of Kentucky research farms. Hemp was planted in a no-till system following mustard or wheat; a conventional tillage plot was also planted. Parameters investigated included FHB severity, airborne inoculum load, grain yield, and mycotoxin contamination. Hemp planted following wheat was exposed to the highest amount of airborne inoculum and had the highest levels of FHB and mycotoxin contamination. Results and observations from this dissertation work will provide FHB management recommendations to Kentucky’s hemp growers and can guide future work regarding fungicide application timings. In addition, the mycotoxin levels observed in this work are the highest reported to date in the US, indicating that more FHB management research is urgently needed to manage contamination and to protect human and livestock consumers.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2026.92

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