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ARS Home » Northeast Area » Geneva, New York » Plant Genetic Resources Unit (PGRU) » Research » Publications at this Location » Publication #427233
Research Project: Conservation, Characterization, Evaluation, and Utilization of Hemp Genetic Resources and Associated Descriptive Information

Location: Plant Genetic Resources Unit (PGRU)

Title: Screening of cannabis sativa germplasm for susceptibility to Septoria Leaf Spot

Author
item SCHWARTZ, JOCELYN - Cornell University
item VIGNALE, LUCIA - Cornell University
item Gordon, Tyler
item Stansell, Zachary
item SMART, LAWRENCE - Cornell University
item SMART, CHRISTINE - Cornell University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2025
Publication Date: 4/15/2026
Citation: Schwartz, J., Vignale, L., Gordon, T.C., Stansell, Z.J., Smart, L.B., Smart, C.D. 2026. Screening of cannabis sativa germplasm for susceptibility to Septoria Leaf Spot. Plant Disease. 110(5):1505-1996. https://doi.org/10.1094/PDIS-07-25-1367-RE.
DOI: https://doi.org/10.1094/PDIS-07-25-1367-RE

Interpretive Summary: Hemp can be utilized for a variety of industrial applications including textiles, foods, oils, and building materials. Septoria leaf spot is a common fungal disease of field grown hemp. The development of resistant cultivars is an effective disease management strategy. The goal of this study was to evaluate diverse hemp accessions from the USDA hemp germplasm repository for field resistance to Septoria leaf spot. Of the 130 accessions tested over two years, six accessions were found to be consistently resistant to Septoria leaf spot. These resistant accessions can be used for developing resistant breeding lines and identifying molecular markers linked to resistance genes.

Technical Abstract: Septoria leaf spot, caused by the fungal pathogen Septoria cannabis, is a common disease of field-grown hemp (Cannabis sativa L.). The development of disease-resistant cultivars presents a promising strategy for managing this disease. To evaluate the resistance of hemp germplasm to Septoria leaf spot, diverse hemp accessions from the USDA-ARS Plant Genetic Resources Unit and Cornell breeding lines were evaluated in replicated field trials in Geneva, NY. In 2023, 81 accessions were screened, and in 2024, 105 accessions were screened for disease severity on a weekly basis. Relative area under disease progress curve (rAUDPC) values were calculated to quantify susceptibility across two years. Significant variations in rAUDPC were observed among accessions, ranging from 0.0029 to 13 in 2023 and from 0.069 to 20 in 2024. Six accessions that consistently displayed low disease severity and are likely resistant to S. cannabis were identified. Disease severity was not significantly correlated with plant sex. Several resistant accessions were of Asian origin. This study establishes foundational knowledge for breeding programs targeting Septoria leaf spot resistance and emphasizes the value of diverse hemp germplasm in disease management.