Annual Broadleaf Weeds

bromoxynil (Several trade names)

Rate 0.25 to 0.38 lb ai/a (0.5 lb ai/a allowed with chemigation application only)

Time Apply to established mint in early spring using lower rate. In autumn, there is more crop safety and applications can be made to spring-planted or established mint. Do not apply within 2 weeks of a terbacil (Sinbar) application.

Remarks Crop injury may be unacceptable if applied when temperature is expected to exceed 70°F for the first 5 days after treatment. Injury is less likely in fall. For best results, treat when weeds have fewer than four leaves, or when rosettes are less than 1.5 inches across. Use multiple applications if needed, but do not exceed 1.5 lb ai/a per growing season (6 pints/a for 2 lb bromoxynnil/gal and 3 pints/a for 4 lb bromoxynil/gal. Use 10 to 20 gal/a water in ground applications or 5 to 10 gal/a water by air. May also be applied through sprinkler irrigation systems to dormant mint.

Caution Preharvest interval is 70 days. May stunt or discolor mint. Do not apply to mint growing under adverse conditions including disease, insects, high salt, drought, or excessive moisture. Applications to mint growing under cool, cloudy weather and favorable moisture conditions followed by hot conditions, may cause leaf burn and can stunt mint. Do not tank-mix with terbacil when mint is actively growing because the crop may be injured. Do not plant rotational crops within 30 days of product application.

Site of action Group 6: photosystem II inhibitor

Chemical family Nitrile

carfentrazone (Aim EC)

Rate 0.008 to 0.03 lb ai/a (0.5 to 1.92 fl oz/a) + nonionic surfactant or crop oil concentrate or methylated seed oil

Time Apply to dormant mint

Remarks Apply in at least 10 gal/a water by ground or 5 gal/a by air. Always add nonionic surfactant or crop oil concentrate or methylated seed oil as specified on label. Controls only broadleaf weeds. Weeds should be succulent, growing, and small at application. Weeds that germinate after application will not be controlled. Use higher rates when weeds are under stress or larger. Liquid nitrogen fertilizer or ammonium sulfate additives are allowed in spray mixture.

Caution Do not apply after mint breaks dormancy and begins spring growth. Green mint foliage present at application will be injured. Do not apply within 5 days of harvest.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Triazolinone

oxyfluorfen (Several trade names)

Rate 0.5 lb ai/a in western Oregon (Willamette Valley). In other areas, use 0.75 to 1.5 lb ai/a (2-3 pints/a of Goal 2XL)

Time Apply only to established, dormant mint before weeds exceed 2 to 4 inches in diameter or height. West of Cascades, treatments in December, January and through February generally provide best results. In other areas, apply from December through early March. Injury can be serious if spring growth has begun before application. Use the higher rates for longer weed control.

Remarks Add 1 quart/100 gal nonionic surfactant. Non-tilled mint may be injured; the injury is believed to occur when herbicide contacts roots and rhizomes growing near the soil surface. Apply oxyfluorfen only to strong, healthy mint. Controls annual bluegrass, Italian ryegrass, and wild oat if applied preemergence. The addition of paraquat improves weed control, especially grasses. This combination is more effective on many weeds than either herbicide alone. Paraquat is a restricted-use herbicide. Check the 'cautions' section in this handbook and read the label carefully before using.

Caution Do not apply to emerged mint. Do not apply to plowed mint in the Willamette Valley. East of Cascades, do not harrow plowed fields after application. In furrow-irrigated mint, corrugating must be done before application. Do not apply to mint weakened by disease, nematodes, insects, winter injury, high salt, or other factors because severe injury may result. Do not apply to frozen ground.

Site of action Group 14: protoporphyrinogen oxidase (PPO) inhibitor

Chemical family Diphenylether