Submitted to: World Journal of Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2011
Publication Date: 1/15/2012
Publication URL: http://handle.nal.usda.gov/10113/60786
Citation: Weaver, M.A., Boyette, C.D., Hoagland, R.E. 2012. Bioherbicidal activity from washed spores of Mycrothecium verrucaria. World Journal of Microbiology and Biotechnology. 28:1941-1946. Interpretive Summary: An aggressive pathogen of kudzu and several other important weeds has been identified and is being developed for use as a bioherbicide. This pathogen, Myrothecium verrucaria, however, also produces metabolites that are toxic to humans. The present study evaluated changes in the way the fungal spores are grown and processed that can reduce the amount of toxins in the formulated product. It was demonstrated that manipulating the nutrient composition during growth and washing the spores with water can yield a formulated product that is pathogenic to weeds. This will allow the development of safer formulations of this biological control agent.
Technical Abstract: The fungal plant pathogen, Myrothecium verrucaria, is highly virulent to several important weed species and has potential utility as a bioherbicide. However the production of macrocyclic trichothecene mycotoxins by this fungus presents significant safety concerns. It was discovered that trichothecenes are removed from M. verrucaria spores by repeated washes with water. These washed spores retained bioherbicidal efficacy against kudzu when tested in field trials and on sicklepod when tested under greenhouse conditions. Changes in the growth medium and washing spores resulted in greater than 95% reduction in roridin A and verrucarin A. Washing spores reduced trichothecene concentrations in spore preparations with no significant effect on plant biomass reduction, thus demonstrating the possibility of M. verrucaria formulations with improved safety to researchers, producers and applicators.