Deploying Microbes as a Seed Treatment to Protect Against Soil-borne Plant Pathogens


Plant diseases, especially those caused by soil-borne seed infecting pathogens, pose a serious threat to organic greenhouse and field production. There is a critical need for new techniques and technologies to combat seed and seedling diseases, and organic farmers have identified this as a top research priority.

Both solid and liquid forms of organic amendments such as compost and vermicompost have proven successful in controlling plant pathogens. The working hypothesis is that microbes are closely associated with disease suppression. OFRF provided a research grant in 2014 to Rick Carr at the Rodale Institute (pictured in photo) to establish a proof-of-concept that compost microbes can be deployed on the surface of seeds before sowing to protect against soil-borne plant pathogens. He recently submitted his final project report.


Carr engaged several stakeholder groups, including organic vegetable producers, a seed industry collaborator, and faculty, students, and staff at Cornell University, Kutztown University, and Rodale Institute. The research centered on determining whether freeze-dried compost extract is effective as a seed treatment for protection against soil-borne plant pathogens.

Although complete disease control was not achieved using freeze-dried compost extract, the results from this project demonstrated that the level of disease suppression increases with the rate of freeze-dried compost extract application. The ability to produce enough freeze-dried compost extract during this project prohibited further exploration, but production techniques were identified so that the freeze-drying process can yield greater results in the future.

Carr concludes that increased exploration into the use of freeze-dried compost extract as a seed treatment would reveal the full potential for suppressing soil-borne plant pathogens. The concept has been presented to numerous audiences. Once the efficacy of the seed treatment has been determined, and if shown to be successful at controlling disease, the technology will be shared with the entire agricultural industry.

Read the project summary here.