Aquatic Bioherbicidal Formulation Development for Mycoleptodiscus terrestris

Multiple exotic, invasive aquatic weeds have been introduced into the United States in the last century with major negative impacts including reduced floodwater control, disruptions to navigation, recreation, irrigation and water intake systems, and degradation of wildlife habitat. Introduced into the US in the late 1950s, the most problematic aquatic weed in the United States is currently hydrilla (Hydrilla verticillata). There is a shortage of effective, environmentally appropriate options for management of hydrilla. The use of an inundative, plant-specific pathogen for selective weed control with minimal water quality concerns would be a highly desirable approach for hydrilla management. Mycoleptodiscus terrestris (Mt) is an aquatic weed pathogen first examined for use as an inundative bioherbicide for submersed weed biocontrol in the 1970s. Initial efforts at development and commercialization were not successful due in part to lack of pathogen stability. A recent cooperative research effort between the US Department of Agriculture, the US Army Engineer Research and Development Center, and SePRO Corporation developed new fermentation methods that produce more stable Mt materials. However, a bioherbicidal formulation of these new materials with sufficient virulence for full commercial development has not been identified. The overall goal of Phase I research is focused on determining the feasibility of an effective bioherbicidal formulation of Mt pathogen for commercialization for hydrilla control with potential translation to other target submersed weeds. The specific objectives of this research program are: 1. Test the feasibility of various combinations of Mt pathogen with formulating agents for improved bioherbicide efficacy on hydrilla. 2. Quantify changes in several physiological responses of hydrilla in early stages of Mt infection to determine which response best correlates with bioherbicide treatment efficacy. 3. Evaluate best physiological indicator in expanded formulation screening to improve bioassay efficiency for research and future quality assurance purposes. In Phase II, necessary studies would be performed to meet standards for potential Section 3 biopesticide registration with the US Environmental Protection Agency. Ultimately, successful Phase I and II research would form the basis for the successful commercial introduction of a much-needed aquatic bioherbicide, a technology with a unique fit for a highly environmentally-sensitive market.