Submitted to: Proceedings Mint Industry Research Council
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2001
Publication Date: 1/1/2002
Citation: BOYDSTON, R.A., BAKER, R., BIRCH, L.M. WEED CONTROL RESEARCH IN MINT. PROCEEDINGS MINT INDUSTRY RESEARCH COUNCIL, LAS VEGAS, NV. 2002. Interpretive Summary: Weeds lower mint oil yield and quality. Weed control represents a major production cost and investment of time for growers. The goal of this research is to develop improved weed control methods in spearmint and peppermint and to identify promising new herbicides on spearmint and peppermint. Several herbicides were identified that were safe on mint while controlling several problem weeds. Flumioxazin, sulfentrazone, fluroxypyr, and a new formulation of pendimethalin controlled weeds in mint and offer several new herbicide chemistries for use in mint. Residue data needed for registration of flumioxazin in spearmint and peppermint were completed and submitted to IR-4 headquarters. Western salisfy, a commonly missed weed in mint fields was controlled with oxyfluorfen, terbacil, flumioxazin and sulfentrazone in greenhouse tests.
Technical Abstract: In greenhouse trials, Western salsify, a difficult to control weed in mint, was controlled with preemergence applied flumioxazin, sulfentrazone, terbacil and oxyfluorfen. In field trials, sulfentrazone and flumioxazin applied preemergence in fall or spring were safe on native spearmint and peppermint, whereas two sulfonylurea herbicides, halosulfuron and pyrithiobac, were not. Sulfentrazone controlled yellow nutsedge 85% in peppermint. Flumioxazin applied preemergence at 0.047 and 0.094 lb ai/a slightly injured newly planted peppermint and controlled annual weeds well. Sulfentrazone, two formulations of pendimethalin, and terbacil controlled pigweed, kochia, common lambsquarters, and barnyardgrass well with minimal injury to newly planted peppermint. Initial injury to established peppermint was less with a 3.8 lb ai/gal formulation of pendimethalin than with the standard 3.3 lb ai/gal formulation. Flumioxazin and sulfentrazone controlled kochia and common lambsquarters well in peppermint. Fluroxypyr, pyrithiobac, and 2,4-DB applied postemergence suppressed field bindweed growth, but did not reduce the number of field bindweed in native spearmint. Fluroxypyr applied to native spearmint caused increasing injury as rate increased from 0.063 to 0.25 lb ai/a and as time of application was delayed in relation to spearmint growth.