Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2005
Publication Date: 1/1/2006
Citation: Boydston, R.A., Baker, R. 2006. Weed research. Mint Industry Research Council 2005 Research Reports. Pp. 23.
Technical Abstract: Weeds in peppermint and spearmint reduce mint oil yield and quality. Presence of weeds in mint hay at harvest can result in off flavors, odors, and colors in the oil. Several weed species have developed resistance to, or are poorly controlled by herbicides labeled for mint production. Pigweed is often a problem weed emerging immediately after the first harvest of mint. Flumioxazin impregnated on ammonium sulfate or urea fertilizer did not injure peppermint or reduce oil yields applied after the first cutting and reduced pigweed incidence. Low rates of mesotrione and sulfentrazone applied postemergence to peppermint controlled pigweed and caused only transient peppermint injury. Tolerance of peppermint, Scotch spearmint, and native spearmint to auxin inhibitor herbicides MCPB, clopyralid, fluroxypyr, dicamba, triclopyr, and dicamba plus diflufenzopyr applied at three rates was tested in green house and field trials. All auxin inhibitor type herbicides injured mint to some degree and reduced oil yield in some circumstances depending on mint type and herbicide rate in both field and green house trials. Overall, MCPB and clopyralid injured mint the least. Experimental herbicides flucarbazone, and propoxycarbazone applied to dormant native spearmint caused little or no crop injury.