Finding disease-resistant hemp varieties to fight fungal infections

This study evaluated disease resistance across hundreds of hemp cultivars to Septoria leaf spot, a fungal infection that commonly affects field-grown cannabis. Researchers screened 81 hemp varieties in 2023 and 105 in 2024, measuring how susceptible each plant was to the pathogen Septoria cannabis. They found dramatic variation in resistance levels, with some plants showing nearly zero infection while others developed severe leaf damage exceeding 30% of foliage.

The researchers identified nine elite hemp varieties that consistently demonstrated strong resistance to Septoria leaf spot across both years of testing. Interestingly, several of these resistant varieties originated from Asia, suggesting that genetic diversity from different geographical regions holds valuable disease-fighting traits. Notably, disease severity was not related to plant sex, meaning both male and female plants showed similar resistance patterns. This finding is important because it means breeders have flexibility in selecting for disease resistance without concerns about sex-based vulnerabilities.

This research provides crucial foundational knowledge for developing disease-resistant hemp cultivars through selective breeding programs. By identifying resistant varieties and understanding the genetic basis of disease resistance, hemp farmers can reduce reliance on fungicide applications and improve crop yields naturally. The study emphasizes that genetic diversity in hemp germplasm—particularly varieties adapted to different climates—offers practical solutions for disease management, potentially benefiting both conventional growers and cannabis producers facing similar pathogenic challenges.