P-145 - Crop rotation and fumigation effects on soil-borne pathogens and potato yield

Monday, August 4, 2025

3:45 PM - 4:30 PM HST

Location: Exhibit Hall 3

Presenting Author(s)

PI

Pear Intasin (she/her/hers)

Graduate Research Assistant
Oregon State University
Corvallis, Oregon, United States

Author(s)

MO

Michelle E. Odoi

Post Doctoral Fellow
Oregon State University
Hermiston, Oregon, United States
VS

Victoria Skillman

Faculty Research Assistant
Oregon State University
Hermiston, Oregon, United States
KF

Kenneth Frost

Associate Professor
Oregon State University
Hermiston, Oregon, United States

Abstract Text: Potato production in the Columbia Basin achieves some of the highest yields in North America. However, soilborne pathogens pose a threat to potato yield and quality each year. To mitigate the effects of these pathogens, practices such as soil fumigation and crop rotation are commonly used. This study investigated how rotation length and fumigant type affected soilborne pathogen abundance and potato yield. We evaluated changes to soilborne pathogen abundance and potato yield following three treatments, 1) fumigation with metam sodium, 2) fumigation with chloropicrin, and 3) no fumigation, in continuous and three-year potato rotation experiments conducted from 2019 to 2022. In 2022, soils were sampled at planting, row closure, and harvest and cultured for Pythium spp., Metalaxyl-resistant (MR) isolates of Pythium spp., Fusarium spp., Verticilium dahliae, and Colletotrichum coccodes. Potato yield and specific gravity were determined at harvest. Potato yield varied as a function of fumigation (P = 0.022) and rotation length (P < 0.001). Moreover, fumigation significantly influenced the abundance of all measured pathogens (P_all< 0.05), while rotation length only affected Pythium spp. abundance (P < 0.001). No interaction between fumigation and rotation length was observed for any of the measured variables. Interestingly, Pythium spp. abundance explained 29.2% of yield variation, with a yield loss of 0.106 Mg ha^-1 for each additional CFU observed in culture. In short, rotation length had a greater impact on yield than fumigation, possibly by reducing Pythium spp. abundance.