Winter Annual Grasses

imazapic (several products)

Rate 0.031 to 0.094 lb ae/A (2 to 6 oz/A); 0.125 to 0.188 lb ae/A (8 to 12 oz/A) for perennial weed control/suppression

Time Apply preemergence and postemergence. Controls certain broadleaves and annual grasses. Maximum weed size 2 to 6 inches on postemergence applications.

Remarks Some brush and tree species are tolerant to imazapic as a directed application under the canopy. See label for list of tolerant plants.

Caution Always use adjuvant; see label for details.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Imidazolinone

imazethapyr (several products)

Rate 0.0625 lb ae/A

Time Apply postemergence to seedling legumes or to established legumes when weeds are actively growing, but before they exceed 3 inches. May be applied in fall or spring to established legumes.

Remarks Apply only once per year. Apply to these legumes: alfalfa, clovers, crownvetch, birdsfoot trefoil, and lespedeza. May be applied to these grasses: big bluestem, little bluestem, switchgrass, Russian wildrye, intermediate wheatgrass, crested wheatgrass, western wheatgrass, tall wheatgrass, smooth brome, canarygrass, and orchardgrass.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Imidazolinone

pronamide (Kerb)

Rate 0.2 lb ai/A (0.4 lb/A Kerb)

Time Between mid-October and mid-December.

Remarks For CRP fields with an acceptable stand of grass that has been established at least 1 year. Sufficient moisture is required after application to move herbicide into the root zone of susceptible germinating weeds.

Caution A restricted-use herbicide. Species showing satisfactory tolerance to pronamide are tall fescue, creeping foxtail, orchardgrass, crested wheatgrass, intermediate wheatgrass, slender wheatgrass, tall wheatgrass, and western wheatgrass.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Benzamide

propoxycarbazone-sodium (Lambient)

Rate 0.04 to 0.05 lb ai/A propoxycarbazone-sodium (0.9 to 1.2 oz/A Lambient)

Time For postemergence control of grass and broadleaf weed species common to CRP, including downy brome. For best control of brome species, apply at the 2- to 3-leaf growth stage.

Remarks See Lambient label for the list of CRP grasses that are tolerant to propoxycarbazone-sodium and for list of broadleaf weeds controlled. Use with a nonionic surfactant and UAN or AMS may be added to the spray solution to enhance weed control.

Caution Do not exceed more than 1.2 oz of Lambient per year. See label for guideline on recropping intervals following application to CRP.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Sulfonylaminocarbonyltriazolinone

sulfosulfuron (Outrider)

Rate 0.06 to 0.09 lb ai/A sulfosulfuron (1.33 to 2.0 oz/A Outrider)

Time For postemergence control of grass and broadleaf weed species common to CRP, including downy brome and tarweed. For best control of brome species, apply at the two- to three-leaf growth stage.

Remarks See Outrider label for the list of CRP grasses that are tolerant to sulfosulfuron. Use with a 90% ai nonionic surfactant at a rate of 1 quart/100 gal of spray solution.

Caution Sequential applications of Outrider may be made 30 days apart, but do not exceed more than 2.66 oz of Outrider per year. Do not apply to newly-seeded CRP grasses prior to the 3-leaf growth stage or reseed tolerant grasses into treated areas prior to 14 days after application.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Sulfonylurea

triasulfuron (Amber)

Rate 0.013 to 0.026 lb ai/A (0.28 to 0.56 oz/A Amber)

Time Postemergence to actively growing broadleaf weeds.

Remarks Label lists established desirable grasses to which applications can be made. Downy brome and cheat can be partially controlled by Amber at 0.56 oz/A before those grasses emerge.

Caution Triasulfuron will severely injure desirable broadleaves such as clovers and alfalfa.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Sulfonylurea