Field scale application of Brassica seed meal and anaerobic soil disinfestation for the control of replant disease

Authors: DUPONT, TIANNA - Washington State University; HEWAVITHARANA, SHASHIKA - California Polytechnic State University; MAZZOLA, MARK - Former ARS Employee

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2021
Publication Date: 6/6/2021
Citation: DuPont, T., Hewavitharana, S., Mazzola, M. 2021. Field scale application of Brassica seed meal and anaerobic soil disinfestation for the control of replant disease. Applied Soil Ecology. 166. Article 104076. https://doi.org/10.1016/j.apsoil.2021.104076.
DOI: https://doi.org/10.1016/j.apsoil.2021.104076

Interpretive Summary: Organic soil amendments often have been promoted as a means to control soilborne plant diseases. However, the effective use of individual amendments for the control of biologically complex diseases seems improbable. Our previous studies conducted in small (0.5 acre) field plots demonstrated that a Brassicaceae seed mela formulation could provide effective control of apple replant disease and resulted in an orchard system that was capable of delaying recolonization by plant pathogens including lesion nematode and the root rotting organism Pythium spp. The current study was conducted the commercial orchard scale (up to 11 acres in size) to assess the practicality of alternative disease control practices for control of this biologically complex disease syndrome. At three 1 to ll acre field sites in Washington State, anaerobic soil disinfestation and Brassica seed meal soil amendment were compared to no-treatment controls and fumigation with 1,3-dichloropropene/chloropicrin. At all three orchard sites the Brassica seed meal treatment significantly altered composition of the bulk soil and rhizosphere microbiome and resulted in apple tree growth as great or greater than soil fumigation. Anaerobic soil disinfestation resulted in significant changes to composition of the rhizosphere microbiome and tree growth that was greater than the no-treatment control in three of four experiments. Our findings indicated that both methods may serve as biologically effective alternatives to soil fumigation for control of apple replant disease. These studies also demonstrated the consistent long-term resilience of the commercial orchard soil system in regards to suppression of plant parasitic lesion nematodes.

Technical Abstract: Apple replant disease caused by a complex of soil-borne fungi, oomycetes, and nematodes causes stunting and reduced yields when apples are planted in locations previously cropped to tree fruit. Anaerobic soil disinfestation and bio-renovation using mustard seed meals have successfully mitigated replant disease in greenhouse trials and small field plots. To our knowledge this is the first study to evaluate the efficacy of Brassica seed meal and anaerobic soil disinfestation for the control of replant disease at a commercial scale in apples. At three 0.4 to 5 ha field sites in Washington State, anaerobic soil disinfestation and Brassica seed meal bio-renovation were compared to no-treatment controls and fumigation with 1,3-dichloropropene/chloropicrin. Brassica seed meal treatments significantly altered composition of the bulk soil and rhizosphere microbiome and resulted in apple tree growth as great or greater than fumigated controls across all three study locations. This included consistent changes in specific microbial groups potentially functional in disease suppression across all three orchard sites. These included amplification in relative abundance among members of the fungal genera Chaetomium, Talaromyces, Gelasinospora and Hypocrea/Trichoderma as well as bacteria in the genus Streptomyces and the phylum Firmicutes. Anaerobic soil disinfestation resulted in significant changes to composition of the rhizosphere microbiome and tree growth that was greater than the no-treatment control in three of four experiments. Our findings indicated that both methods may serve as biologically effective alternatives to soil fumigation for control of apple replant disease, though further modifications may be required to ensure their economic feasibility.