Comparative Analysis of Hemp and Wheat Fusarium graminearum Populations.

Fusarium head blight (FHB) has emerged as one of the most important diseases of hemp in the United States. The disease has been documented in four of five diagnostic regions and results in extensive blighting of flower and grain heads. Because of production similarities between grain hemp and agronomic crops, hemp is likely to be rotated with crops such as wheat as acreage increases. As a result of the near 50-year hemp production ban and the different selection forces encountered in hemp and wheat production systems, it was hypothesized that hemp and wheat isolates of Fusarium graminearum might have phenotypic differences. To test this hypothesis the growth rate, sporulation, fungicide sensitivity, pathogenicity to hemp and wheat, and deoxynivalenol contamination of 12 isolates originating from FHB symptomatic hemp and wheat in Kentucky were compared. The isolates did not statistically differ in any trait examined in this study. However, isolates tended to be slightly more aggressive on their host of origin in pathogenicity tests. The ability of F. graminearum to cross-infect and cause high levels of disease regardless of host of origin could result in a buildup of inoculum that could be problematic from an FHB management perspective in both hemp and wheat production.