Enhancing Indigenous Soil Microflora to Facilitate Organic Strawberry Transition in the Southeastern US
Project Director
David M. Butler
Year Funded
2019
Award Number
2019-51106-30197
Funded Institution
University of Tennessee
Grant Program
ORG (Organic Transitions)
USDA NIFA Report
Project Overview
Organic strawberry growers need effective alternatives to soil fumigation to manage the black root rot disease complex. This project evaluated anaerobic soil disinfestation (ASD) before planting, treatment of strawberry starts with native strains of Trichoderma, and commercial mycorrhizal biostimulants against root rot. For ASD, wheat cover crops at different growth stages and lignin:nitrogen (N) ratios were incorporated as the organic carbon source driving anaerobic microbial activity during the soil-saturated incubation period. Impacts on pathogens and beneficial organisms, including applied Trichoderma, were assessed.
Farmer Takeaways
(1) Anaerobic soil disinfestation (ASD) is an organic alternative to soil fumigation, in which organic residues are tilled in and the soil is watered to saturation and tarped for several weeks to promote disease-suppressive anaerobic decomposition.
(2) ASD suppresses strawberry root rots, reduces weeds, and boosts strawberry yield.
(3) High-N, low-lignin residues like young, green cover crops or brewer’s spent grains (BSG) work better for ASD than high-lignin low-N materials like a mature cereal grain.
(4) ASD with high-N materials can boost soil N levels and may increase N leaching.
(5) Crop rotation, especially with sorghum-sudangrass, enhances disease control by ASD.
(6) Applying distiller’s yeast with BSG can enhance strawberry disease control by ASD.
Project Outputs
Littrell, J.J., B.H. Ownley, Z.R. Hansen, K.D. Gwinn, and D.M. Butler. 2025. Role of organic amendment composition and soil texture in modulating volatile fatty acids, Fe/Mn reduction, and Fusarium oxysporum suppression during anaerobic soil disinfestation in neutral to alkaline soils. Phytopathology.
Liu, D., J.B. Samtani, and D.M. Butler. 2025. Effect of anaerobic soil disinfestation with yeast amendment on weed control and strawberry yield. HortScience 60:1510–1520.
Littrell, J.J., B.H. Ownley, and D.M. Butler. 2024. Unraveling the interplay: Soil biogeochemical factors shaping the efficacy of anaerobic soil disinfestation in suppressing Fusarium root rot of strawberry. Phytopathology 114:1782-1790.
Shrestha, U., B.H. Ownley, J.J. Littrell, J.H. Rice, and D.M. Butler. 2024. Anaerobic soil disinfestation and crop rotation with cover crops enhances management of black root rot in strawberry systems. Scientia Horticulturae 337:113504.
Shrestha, U., M.E. Dee, J.J. Littrell, J.H. Rice, W. Ouma, B.H. Ownley, and D.M. Butler. 2024. First report of root rot of strawberry caused by Fusarium cugenangense, a member of the F. oxysporum species complex, in Tennessee, USA. Plant Disease 108:2238.
U. Shrestha, M.E. Dee, B.H. Ownley, and D.M. Butler. 2023. First Report of Strawberry Black Root Rot Caused by Globisporangium sylvaticum in Tennessee, U.S.A. Plant Disease. 107:9, 2890.