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ARS Home » Pacific West Area » Wenatchee, Washington » Physiology and Pathology of Tree Fruits Research » Research » Research Project #439719

Research Project: Directing Plant-Microbe Relations Toward Resiliency Post-Fumigation

Location: Physiology and Pathology of Tree Fruits Research

Project Number: 2094-21220-003-002-T
Project Type: Trust Fund Cooperative Agreement

Start Date: Apr 1, 2021
End Date: Mar 31, 2023

1. To evaluate select soil amendments for the ability to recruit and support a microbiome in fumigated soil that is resilient to pathogen invasion and also improve other characteristics of healthy soil (nutrient availability, water holding capacity, etc.) 2. To determine the role of select amendment-modified soil microbial communities in limiting pathogen re-infestation and reducing potential post-harvest pathogens.

The ability of a variety of different soil amendments to alter the trajectory of the soil microbiome in a way that promotes beneficial microbial groups possessing the potential to control soil-borne pathogen re-infestation (following orchard soil fumigation) will be assessed. This will be done using standard amplicon sequencing methods for the identification of bacteria and fungi present within a soil sample. These microbial "steering" experiments will be conducted on microbial communities associated with the rhizospheres of replant "tolerant" apple rootstocks planted into fumigated soil amended with Brassica seed meal, as well as other easily attainable and cost-effective amendments commonly used in the industry. The microbial community sequence data will also be used to assess the impact of these amendment-modified soil microbial communities on limiting potential post-harvest pathogens. At the same time, the different treatments will be evaluated in terms of their ability to improve a number of other abiotic "soil health" characteristics including soil nutrients, organic matter, and physical composition. These analysis will be conducted at an approved soil/compost testing laboratory. The most promising soil-amendments will be selected and used in a subsequent experiment designed to directly test the ability of the apple root tissue to resist pathogen re-invasion following fumigation. In order to simulate pathogen re-invasion following fumigation, specific apple replant pathogens will be added to fumigated soil containing select soil amendments. These pots will then be planted with the same apple rootstock used in the initial experiment. Microbial DNA will be extracted from apple root tissue and pathogen levels will be determined using previously developed qPCR assays. Analysis of rhizosphere soil will also be conducted to verify that the amendments induced the expected shifts in the microbial community.