Using Bioassays to Quantify Pathogen Dynamics in Soil Amended with Organic Fertilizers.

Organic fertilizers can replenish soil organic matter, supply nutrients, and influence disease incidence on vegetable farms. However, amendment composition and site-specific soil and climatic factors that are not well understood affect these processes, making management challenging. In this project, repeated applications of four organic fertility amendments (chicken manure, plant/animal byproducts, vermicompost, animal byproducts) are being evaluated on three organic vegetable farms in Indiana and Ohio.   Soil collected from each plot was tested in bioassays for efficacy against Rhizoctonia solani.  Severity of disease on snap bean (cv. Valentino) was effected by specific soil types, amendment and location.