Location: Biological Control of Pests Research
2017 Annual Report
Accomplishments
1. Efficacy improvement of bioherbicides via formulation. Bioherbicides can offer an effective alternative control strategy to chemical herbicides, but must be properly formulated in order to maximize effectiveness. USDA-ARS researchers in Stoneville, Mississippi, demonstrated that a strain of the fungus Colletotrichum (C.) coccodes isolated from eastern black nightshade was effective in controlling this weed under sub-optimal free-moisture (dew) conditions when fungal spores were formulated in an invert emulsion. These results demonstrate that formulating C. coccodes spores in an invert emulsion greatly improves the bioherbicidal potential of this fungus. Furthermore, results suggest that this formulation may render pathogens previously rejected for development as bioherbicides due to restrictive dew requirements more efficacious for use in controlling their target weeds.
2. Bioherbicides to control weeds. ARS scientists at Stoneville, Mississippi, evaluated phytopathogenic fungi as bioherbicides. Research continued on the evaluation of a reduced mycotoxin formulation of Myrothecium verrucaria (Mv) and mutant strains of Mv for control of kudzu and other invasive weeds. Comparative studies on mycelial preparations of Mv and a recently discovered sector (Mv-Sector BSH) of this fungus were carried out. The whitish sector was isolated and grown in pure culture on potato dextrose agar and found to be a stable, non-spore producing mutant when cultured over several months under conditions that cause circadian sporulation during growth of its Mv parent. Application of Mv and Mv-Sector BSH mycelial preparations to intact weed seedlings (hemp sesbania and sicklepod) and leaf discs of weeds (kudzu and glyphosate-resistant Palmer amaranth) showed that the sector efficacy was generally equal to, or slightly lower than Mv. Results indicate that certain bioherbicides have utility in controlling herbicide-resistant and recalcitrant weeds.
Review Publications
Boyette, C.D., Hoagland, R.E., Stetina, K.C. 2016. Efficacy improvement of a bioherbicidal fungus using a formulation-based approach. American Journal of Plant Sciences. 7:2349-2358.
Hoagland, R.E., Boyette, C.D., Stetina, K.C., Jordan, R.H. 2016. Bioherbicidal efficacy of a Myrothecium verrucaria-sector on several plant species. American Journal of Plant Sciences. 7:2376-2389.
Hoagland, R.E., Boyette, C.D. 2016. Controlling herbicide-susceptible, -tolerant and -resistant weeds with microbial bioherbicides. Outlooks on Pest Management. 27:256-266.
