The effects of azoxystrobin on rhizosphere microbiology and microbiome-mediated susceptibility to Rhizoctonia solani AG 2.2 in table beet

View the project final report

Commodities

• Vegetables: beets

Practices

• Natural Resources/Environment: biodiversity
• Pest Management: biological control, chemical control
• Soil Management: soil microbiology

This project seeks to assess the impact of agricultural pesticide application on the rhizosphere microbiome of table beets and microbiome-mediated susceptibility to root disease. Recent expansion of table beet production in New York is limited by root rot caused by Rhizoctonia solani AG 2.2. The fungicide azoxystrobin is applied annually for disease control without regard to risk or off-target effects. These in-furrow fungicide applications can affect non-target organisms of the beet rhizosphere microbiome. By disturbing the balance of the microbial community, certain protective effects from the rhizosphere microbiome may be lost. While azoxystrobin has been shown to alter microbiome composition in the soil, no studies have yet evaluated the impacts on beneficial members of the root-associated microbiome. To address these in a replicated field trial, treatments will be +/- azoxystrobin (applied at planting) and +/- R. solani inoculum. For each treatment, rhizosphere sampling will occur at two and eight weeks after seedling emergence. DNA extractions, next-generation sequencing, and taxonomic annotations will provide detailed information on composition of the microbiome. Using multivariate analysis, disease ratings will be correlated to microbiome diversity to assess microbiome effects on R. solani. The results of this research will immediately benefit soil health and table beet farmers by providing evidence supporting a sustainable disease management program, particularly through judicious use of fungicides. More broadly, microbiome function will be directly tied to specific microbial taxa, opening the possibility of improved disease control via microbial symbionts, applicable as a model system to broadacre farming in the Northeastern USA.

Objective 1:

Investigate how azoxystrobin impacts the structure and diversity of the rhizosphere microbiome in table beets

Hypothesis 1A:          

The table beet rhizosphere microbiome will be less diverse in soils with azoxystrobin applications compared to soils without azoxystrobin.

Hypothesis 1B:

In the table beet microbiome, hub taxa, or dominating species, will clearly differentiate between soils with and without azoxystrobin

Objective 2:

Determine how azoxystrobin affects the ability of R. solani to cause disease in table beets

Hypothesis 2:

Differences in the beet rhizosphere microbiome caused by previous azoxystrobin applications will correlate to different levels of Rhizoctonia root rot following inoculation.