ARS | Publication request: Viability of the bioherbicide Myrothecium verrucaria in tank-mix suspensions: effect of herbicide formulation, rate and suspension time

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 26, 2006
Publication Date: February 5, 2007
Citation: Weaver, M.A., Lyn, M.E., Boyette, C.D., Hoagland, R.E. 2007. Viability of the bioherbicide Myrothecium verrucaria in tank-mix suspensions: effect of herbicide formulation, rate and suspension time. Weed Science Society of America Meeting Abstracts.

Technical Abstract: Myrothercium verrucaria (MV) is a fungal plant pathogen with a broad weed control spectrum that has been shown to control many agronomical and environmentally important weeds. Because of the unique mode of action of MV and its broad spectrum of control, it might be applied with conventional herbicides in order to avoid the development of resistance, improve control efficacy, or expand the control spectrum. However, the viability of MV after being tank-mixed with formulated products is unknown. The objective of this study was to determine the effect of formulated herbicides [acifluorfen (Ultra Blazer), clopyralid (Transline) aminopyralid (Milestone), halosulfuron methyl (Permit), fluoxypyr (Vista), metsulfuron (Escort XP), picloram (Tordon K), picloram + 2,4-D (Tordon 101) and glyphosate (Roundup Weathermax, Roundup Ultra and Touchdown)] concentration (maximum labeled rate, 0.5x and 0.1x) and exposure time (up to 48 hours) on the viability of MV. Independent of rate, the viability of MV was over 80% for 48 hours in suspensions of acifluorfen, aminopyralid and clopyralid. MV had intermediate tolerance (30-80% survival) of fluoxypyr, picloram, picloram + 2,4-D, halosulfuron methyl, and metsulfuron, which necessitated lower application concentrations or only brief incubation periods in the spray tanks to maintain viability. Glyphosate formulations differed greatly in their toxicity to MV, perhaps as a result of differing salts and/or carrier components. Integration of approaches may be required for difficult weeds such as kudzu. These studies provide insight as to the suitable herbicides for tank mixes with MV.