P-342 - Soil-Mediated Disease Suppression of Potato Powdery Scab caused by Spongospora subterranea f. sp. subterranea

Tuesday, August 5, 2025

10:15 AM - 11:00 AM HST

Location: Exhibit Hall 3

Presenting Author(s)

DE

Daniella Echeverria

PhD Candidate
Oregon State University
Corvallis, Oregon, United States

Author(s)

VS

Victoria Skillman

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

Hannah Rivedal, Ph.D.

USDA-ARS, Forage Seed and Cereal Research Unit, Corvallis, OR, USA
Corvallis, Oregon, United States
TT

Todd N. Temple, M.S.

USDA-ARS, Forage Seed and Cereal Research Unit, Corvallis, OR, USA
Corvallis, Oregon, United States
MO

Michelle E. Odoi

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

Kenneth Frost

Associate Professor
Oregon State University
Hermiston, Oregon, United States

Abstract Text: Potatoes are the fourth most important food crop globally and have a U.S. farmgate value of $4 billion annually. Spongospora subterranea f. sp. subterranea (Sss), ubiquitous in the Columbia River Basin, causes Powdery Scab (PS) of Potato, reducing crop quality and value. In 2023, a greenhouse experiment was conducted to compare PS suppressive activity of 6 Oregon soils with varying management histories. Three soil mixtures were tested: Mixture 1 (100% field soil (FS)), Mixture 2 (85% potting mix (PM), 15% FS), and Mixture 3 (85% PM, 15% autoclaved FS), with two controls (100% PM and 100% autoclaved PM). Four replicate 5-gal pots were used for each mixture (n= 92). One ‘Kennebec’ seed tuber was planted in each pot and inoculated with 10 Sss sporosori g^-1 soil. Bulk and rhizosphere soils were sampled 95 days after planting and roots were assessed for infection by counting galls. Plants grown in soil Mixture 3 had more galls g^-1 of dry root (p=0.001). The number of galls g^-1 of dry root varied depending on soil mixture for plants grown in 2 of 6 field soils. Total variation of eukaryotic and bacterial communities was greater in bulk soils than rhizosphere soils. In both rhizosphere and bulk soils, the interaction between soil origin and soil mixture explained 18% and 17% of the variation in eukaryotic and bacterial communities (p< 0.001). Sterilization can alter the PS suppressive activity of soils, indicating a potential biotic mechanism behind disease suppression. However, further research is needed to identify the specific biotic factors contributing to PS suppression.