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ARS Home » Southeast Area » Stoneville, Mississippi » Biological Control of Pests Research » Research » Research Project #430266

Research Project: Bioherbicidal Control of Invasive Weeds with Indigenous Plant Pathogens

Location: Biological Control of Pests Research

2016 Annual Report

Objective 1. Improve the efficacy, environmental safety, and stability of two bioherbicides currently in development, SPFG and Myrothecium verrucaria (Mv), for the management of salvinia and kudzu, respectively. Sub-objective 1.1. Develop safe, efficacious and stable formulations of the bioherbicide SPFG, and determine how interactions with insect herbivores can affect efficacy. Sub-objective 1.2. Reduce or eliminate Mv mycotoxin levels while maintaining high product efficacy.

The research plan has two goals. The first will focus on evaluating and developing a fungal pathogen (referred to as ‘SPFG’ for proprietary purposes) for managing the exotic, invasive aquatic weed, giant salvinia (Salvinia molesta). The second deals with further developing and testing the fungus Myrothecium verrucaria (Mv) for controlling kudzu (Pueraria lobata var. montana) and other invasive weeds. Because Mv spores produce trichothecene mycotoxins, EPA registration has been hindered. A mycelial formulation devoid of, or with extremely low levels of mycotoxins should result in more likelihood for EPA registration. The development of effective bioherbicide formulations will be guided by the ecology of the pest target and an understanding of biotic and abiotic factors that influence the effectiveness of the bioherbicide. Formulations will be developed to compliment the surface chemistry of the pest host and bioherbicide for better attachment and infectivity, as well as to mitigate deleterious environmental factors that reduce or inhibit host-plant infection. The development of commercially-viable microbial pesticides for weeds could provide growers, land managers and homeowners with safe, cost-effective, non-chemical control tools for use in agriculture, chemically-sensitive environments, and natural ecosystems.

Progress Report
Research was initiated for evaluation of a bioherbicidal fungus (called SPFG in this report) for controlling giant salvinia in greenhouse and small field trials. Controlled-environment studies were established to determine the air temperatures for optimal infection and mortality of giant salvinia. Several surfactants were evaluated for their effect on improvement of weed control efficacy. A floating granule formulation was evaluated in greenhouse experiments. Greenhouse experiments were conducted to determine the host range of SPFG. Greenhouse experiments were conducted to evaluate various inoculum concentrations of SPFG for bioherbicidal control of giant salvinia. Highly virulent, rapidly and inexpensively produced mycelial formulations controlled 90-100% of weeds. Data from these experiments will be included in an invention report for the use of SPFG as a biological herbicide for controlling giant salvinia. Research continued on the evaluation of a reduced mycotoxin formulation and mutant strains of Myrothecium verrucaria (Mv) for control of kudzu and other invasive weeds.