Potato (Solanum tuberosum) is susceptible to several fungal pathogens, including Alternaria solani, Alternaria alternata, Rhizoctonia solani, and Colletotrichum coccodes, which can significantly reduce yield and tuber quality. Vine-kill is commonly used by potato producers to facilitate harvest, enhance tuber maturation and skin set, and manage tuber size. This study evaluated how different vine-kill methods affect soil DNA levels of these four fungal pathogens, potato virus Y (PVY) incidence in progeny tubers, and tuber yield and size distribution in the San Luis Valley, Colorado. Treatments included pulling, flailing, and chemical desiccation with Reglone (diquat dibromide) combined with either Aim EC (carfentrazone-ethyl) or Super Tin 4L (triphenyltin hydroxide). Vine-kill methods did not significantly affect yield, size profile, or PVY incidence. However, soil pathogen DNA levels measured as DNA copy number by qPCR varied among treatments and year. In 2022, pulling resulted in the lowest levels of A. solani, A. alternata, and R. solani, and the second lowest level of C. coccodes. In 2023, pulling provided no significant benefit, but in 2025, it reduced soil levels of all four pathogens relative to desiccation and natural senescence, while flailing resulted in the lowest soil pathogen DNA levels in 2025 for both R. solani, and C. coccodes. Between the two commonly used practices, flailing generally resulted in lower fungal pathogen DNA levels detected than chemical desiccation. Overall, pulling and flailing reduced soil fungal pathogen DNA levels, suggesting that vine-kill practices might influence disease management in potato production systems.
Chikh-Ali et al. (2026) studied this question.