Anaerobic Soil Disinfestation to Control Soilborne Pathogen Rhizoctonia solani in Vermont Field Conditions

View the project final report

Commodities

Practices

• Pest Management: anaerobic disinfestation
• Production Systems: organic agriculture
• Soil Management: soil microbiology

The soilborne fungal pathogen, Rhizoctonia solani, is a recurring problem for vegetable growers in Vermont, reducing field lettuce yields up to 50%. Organic farmers lack proven and effective fungicides to manage the pathogen and lack confidence that commercially available biocontrol products are cost-effective. Anaerobic soil disinfestation (ASD) is gaining attention in the US and has proven effective against soilborne pathogens in California and Florida, but has not been tested for effectiveness in the northeastern US. This project will test whether ASD will control R. solani in Vermont field conditions and provide a net positive economic benefit. The longevity and strength of a ASD effect will be tested over two years on two farms with a history of this pathogen. In ASD, a carbon source is added to soil, watered heavily, and tarped until soil becomes anaerobic. This project tests three carbon sources that are commonly used by Vermont farmers (compost, poultry manure, and cover crop) compared to an unamended control. We will quantify disease incidence and severity at consistent crop phenology, and estimate costs associated with labor and materials. Results will be shared at both the Vermont and New England Vegetable and Berry Growers Associations conferences, shared through on-farm demonstrations, and published in peer-reviewed scientific journals.

This project will test whether ASD can be used to control soilborne pathogen R. solani in Vermont field conditions. There are three components: 1) To provide multiple potential management options, we will test multiple carbon sources (compost, poultry manure, and cover crop) that are available and already used by organic farmers against a non-amended control; 2) We will assess efficacy over two years to answer the farmer question “how often do I have to do this?”; and 3) To assess practical and financial viability, a cost benefit analysis will be performed at a micro-scale farm and a > 10 acre farm in collaboration with the farm partners.

If the proposed project demonstrates that ASD successfully controls R. solani in field-grown crops over multiple years at multiple farms, it will offer robust evidence to growers that ASD can be used within existing management strategies to control soilborne pathogens. It would provide justification for investigation of ASD in high tunnels and greenhouse soils. Further, it will enable growers to make informed financial cost benefit decisions about the use of this practice on their farm. Finally, it provides a method to manage a persistent soilborne pathogen that meets organic certification regulations.