Hemp Diagnoses From Four Midwest States in 2023

In 2023 the Plant Clinic at the University of Illinois Urbana-Champaign received hemp (Cannabis sativa L)  samples as part of a multi-state SAC grant focused on commercial industrial hemp production in the Midwest. Samples were collected from two experimental trial plots in Illinois, Indiana, Michigan, and Wisconsin. The trial plot included plants being grown for fiber and seed production. These samples consisted of hemp plants at various stages of growth, ranging from seedlings to fully mature plants just prior to harvest.  The pathogens identified in these samples are summarized in Table 1, categorized by state and diagnosis. At the beginning of the season, diseases such as Cercospora leaf spot were common while towards the end of the season, Botrytis bud and Fusarium flower blight predominated in Alger, MI. Additionally, several plants were diagnosed with “no pathogen found. “We infer that the high temperatures and drought conditions may have played a crucial role in the reduced incidence of diseases this year. Regarding pests, damage caused by corn earworm was the most frequently identified towards the end of the season.