Management to Reduce Weed Problems

2,4-D (several products)

Rate 0.7 to 2 lb ae/A, depending on weed species and size.

Time Depends on target weeds. Apply to grass pastures when annual and biennial broadleaf weeds are small and actively growing, and established perennials are at bud stage, unless indicated otherwise on the label.

Remarks Controls many broadleaf weeds. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage, before flower stalks are apparent. Spray perennial weeds while still seedlings (coming from seed), or wait until bud stage of growth.

Caution Do not allow drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not graze lactating dairy cattle in treated areas for 7 days after application. Preharvest interval is 30 days for hay. Do not permit animals being finished for slaughter to graze treated fields within 3 days of slaughter.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

aminopyralid (Milestone Specialty Herbicide)

Rate 0.049 to 0.108 lb ae/A (3 to 7 fl oz/A)

Time Apply to actively growing broadleaf weeds. Consult label for application rates for specific weeds.

Remarks A nonionic surfactant at 1 to 2 quarts/100 gal of spray enhances control under adverse environmental conditions. Controls several broadleaf weeds. Application rate depends on weed species and stage of growth. Follow main label and supplemental label restrictions for grazing, forage and manure management.

Caution Do not let spray drift onto desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not use treated plant residues for compost. Do not exceed 7 fl oz/A Milestone per year.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

aminopyralid + metsulfuron (Chaparral Specialty Herbicide)

Rate 0.049 to 0.108 lb ae/A aminopyralid + 0.0089 to 0.019 lb ai/A metsulfuron (1.5 to 3.3 oz/A)

Time Apply to actively growing broadleaf weeds. Consult label for application rates for specific weeds.

Remarks A nonionic surfactant applied at 0.25% v/v or crop oil concentrate applied at 1% v/v of spray enhances control under adverse environmental conditions. Chaparral controls many broadleaf weeds. Application rate depends on weed species and stage of growth. Follow main label and supplemental label restrictions for grazing, forage and manure management.

Caution Do not let spray drift onto desirable vegetation; many forbs (desirable broadleaf plants in pastures) will be seriously injured or killed. Do not exceed 3.3 oz/A Chaparral per year. Do not use on grasses grown for seed or on timothy hay or other cool-season grasses grown for hay. Do not overseed pastures with ryegrasses for 4 months following application of Chaparral. Do not use treated plant residues for compost.

Site of action Group 4: synthetic auxin; Group 2: acetolactate synthase (ALS) inhibitor

Chemical family (aminopyralid) Pyridine; (metsulfuron) Sulfonylurea

aminopyralid + 2,4-D (ForeFront R&P Specialty Herbicide)

Rate 0.06 to 0.108 lb ae/A aminopyralid + 0.5 to 0.87 lb ae/A 2,4-D (1.5 to 2.6 pints/A)

Time Apply to actively growing broadleaf weeds. Consult label for application rates for specific weeds.

Remarks A nonionic surfactant applied at 0.25% to 0.5% v/v of spray enhances control under adverse environmental conditions. ForeFront R&P controls many broadleaf weeds. Application rate depends on weed species and stage of growth. Follow main label and supplemental label restrictions for grazing, forage and manure management.

Caution Do not let spray drift onto desirable vegetation; many forbs (desirable broadleaf plants in pastures) will be seriously injured or killed. Do not exceed the broadcast rate of 2.6 pints/A ForeFront R&P per year. Do not use on grasses grown for seed or grasses grown for hay intended for export. Do not use treated plant residues for compost.

Site of action Group 4: synthetic auxins

Chemical family (aminopyralid) Pyridine; (2,4-D) Phenoxy acetic acid

aminopyralid + triclopyr (Capstone Specialty Herbicide)

Rate 0.05 to 0.075 lbs ae/A aminopyralid + 0.5 to 0.75 lb ae/A triclopyr (4 to 6 pints/A)

Time Apply to actively growing broadleaf weeds. Consult label for application rates for specific weeds.

Remarks A nonionic surfactant applied at 0.25 to 0.5% v/v of spray enhances control under adverse environmental conditions. Capstone controls many broadleaf weeds and woody species. Application rate depends on weed species and stage of growth. Follow detailed supplemental label, preharvest intervals and main label restrictions for grazing, forage and manure management.

Caution Do not let spray drift onto desirable vegetation; many forbs (desirable broadleaf plants in pastures) will be seriously injured or killed. Do not use treated plant residues for compost.

Site of action Group 4: synthetic auxin

Chemical family Pyridines

carfentrazone (Aim EC)

Rate 0.0078 to 0.031 lb ai/A (0.5 to 2 fl oz/A Aim EC)

Time Apply to seedling grass pastures (at least 5 leaves) or established grass pastures up to the boot growth stage, and when broadleaf weeds are less than 6 inches tall.

Remarks The use of a nonionic surfactant, crop oil concentrate, or methylated seed oil is required. A high-quality sprayable liquid nitrogen fertilizer may be used at 2% to 4% v/v or AMS at 2 to 4 lb/A, in addition to the nonionic surfactant, COC, or MSO.

Caution There are no feeding or grazing restrictions following applications of Aim. Do not make applications less than 7 days apart or make more than 3 applications per growing season. Do not exceed a total of 5.9 oz/A per growing season.

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

Chemical family Triazinone

chlorsulfuron (Telar XP and others)

Rate 0.19 to 1.0 oz ai/A (0.25 to 1.33 oz/A Telar XP)

Time Apply preemergence or postemergence to actively growing weeds.

Remarks Controls a wide range of broadleaf weeds. For best postemergence application results, apply with a nonionic surfactant. For perennial weed control, the best control occurs when applications are made at the bud to bloom stage or fall rosette growth stage. For annual weeds, apply at the seedling growth stage. There are no grazing restrictions for any livestock, including lactating animals, with application rates of 1 oz ai/A (1.33 oz/A) or less.

Caution Do not allow drift to desirable vegetation. Telar XP injures or kills desirable forbs including broadleaf forage species such as clovers and alfalfa. Bluegrass, bromes, orchardgrass and wheatgrasses tolerate rates of 0.25 to 1.0 oz/A. Fescue, bluestems, lovegrasses and wildrye tolerate rates of 0.25 to 0.5 oz/A. In general, apply to only well-established forage grasses. Do not apply more than 1.33 oz/A of Telar XP per year to pastures.

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

Chemical family Sulfonylurea

clopyralid + 2,4-D (Curtail)

Rate 0.19 to 0.38 lb ae/A clopyralid + 1 to 2 lb ae/A 2,4-D (2 to 4 quarts/A Curtail)

Time Apply to grass pastures when broadleaf weeds are actively growing.

Remarks Controls many broadleaf weeds. Application rate depends on weeds to be controlled and density of the infestation. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage, and before flower stalks become apparent.

Caution Do not allow to drift onto desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants, particularly legumes) can be seriously injured or killed. Do not graze lactating dairy cattle in treated areas for 14 days after application. Do not cut for hay within 7 days of application. Wait at least 2 weeks after application to graze animals scheduled for slaughter in 7 days or less. Do not use hay or straw from treated areas for composting or mulching. Note label restrictions on overseeding or reseeding.

Site of action (both) Group 4: synthetic auxin

Chemical family (clopyralid) pyridine; (2,4-D) phenoxy acetic acid

dicamba + 2,4-D (Weedmaster, Pasturemaster, or Latigo)

Rate 0.5 to 4 pints/A Weedmaster or Pasturemaster, or 0.33 to 2.5 pints/A Latigo, depending on weed species and size at application

Time Depends on target weeds; see label. In general, apply to grass pastures when annual and biennial broadleaf weeds are small and actively growing, and established perennials are at bud stage.

Remarks Controls broadleaf weeds. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage, before flower stalks are apparent. Unless label indicates otherwise, spray perennial weeds while still seedlings (coming from seed), or wait until bud stage of growth.

Caution Do not allow drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants) can be seriously injured or killed. For Weedmaster and Latigo, do not graze lactating dairy cattle in treated areas for 7 days after application. Do not cut for hay for lactating dairy animals within 37 days of application. Do not permit animals being finished for slaughter to graze treated fields within 30 days of slaughter. For Pasturemaster, do not graze dairy animals on treated areas until 21 days after application of 1 gal (1 lb ai/A) or 40 days for up to 2 gal (2 lb ai/A). Remove meat animals from treated areas 30 days prior to slaughter. Do not cut grass hay within 51 days of application of 1 gal (1 lb ai/A) or within 70 days for up to 2 gal (2 lb ai/A). Note label restrictions on overseeding or reseeding.

Site of action (both) Group 4: synthetic auxin

Chemical family (dicamba) benzoic acid; (2,4-D) phenoxy acetic acid

dicamba + diflufenzopyr (Distinct, Overdrive)

Rate 4 to 8 oz/A

Time Apply to grass pastures when annual and biennial broadleaf weeds are small and actively growing. Can also be applied in the fall to senesced knapweed species for control the following spring.

Remarks Controls broadleaf weeds. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage, before flower stalks are apparent.

Caution Do not allow drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants) and legumes can be seriously injured or killed by applications. Use with a nonionic surfactant or methylated seed oil to maximize weed control efficacy. There are no feeding or grazing restrictions when using these products.

Site of action (dicamba) Group 4: synthetic auxin: (diflufenzopyr) Group 19;auxin transport

Chemical family (dicamba) benzoic acid; (diflufenzopyr) semicarbazone

dicamba + halosulfuron (Yukon)

Rate 4 to 8 oz/A

Time Apply to grass pastures when annual and biennial broadleaf weeds and yellow nutsedge are small and actively growing.

Remarks Controls broadleaf weeds and yellow nutsedge. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage, before flower stalks are apparent.

Caution Do not allow drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants) and legumes can be seriously injured or killed by Yukon herbicide. Use with a nonionic surfactant or methylated seed oil to maximize weed control efficacy. There are no grazing restrictions when using Yukon. The preharvest interval for grass forage production is 37 days. Do not apply more than 8 oz of Yukon per year.

Site of action (dicamba) Group 4: synthetic auxin; (halosulfuron) Group 2; acetolactate synthase (ALS) inhibitor

Chemical family (dicamba) benzoic acid; (halosulfuron) sulfonylurea

fluroxypyr (Vista XRT and others )

Rate 0.13 to 0.48 lb ae/A (6 to 22 oz/A Vista XRT)

Time Apply to established grasses when broadleaf weeds and woody brush species are actively growing in noncropland areas, including grazed sites within those areas.

Remarks Only weeds emerged at the time of application will be controlled. Optimum weed control efficacy will occur when applications are made in warm conditions, with ambient temperatures of 55 to 85°F. Use the lower rates on broadleaf weeds less than 4 inches tall. There are no grazing restrictions for lactating or nonlactating dairy animals.

Caution Do not exceed 22 oz/A of Vista XRT per growing season. Preharvest interval is 7 days for hay or silage. Remove meat animals from treated forage at least 2 days before slaughter.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

glyphosate (several products)

Rate Consult label. Several concentrations of glyphosate are available.

Time Depends on weed or brush species to be controlled. Annual weeds are best controlled when small and actively growing. Apply to perennial weeds at or beyond full flower, or in late summer, or fall after seed forms but before a killing frost.

Remarks Controls susceptible grass and broadleaf plants including many desirable grasses and forbs. Use as a spot treatment, treating up to 10% of any area. Repeat applications can be made in the same area at 30-day intervals. Glyphosate is nonselective and may control all vegetation present, so consider reseeding the areas treated.

Caution Will kill forage plants on contact; do not allow drift onto desirable vegetation. Remove livestock before applying, and do not graze or harvest for 14 days after application. Do not exceed 6 lb ae/A or 8 lb ai/A per year.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

halosulfuron (Sandea)

Rate 0.03 to 0.06 lb ai/A halosulfuron (0.66 to 1.33 oz/A Sandea)

Time Apply to pasture when yellow nutsedge is small and actively growing.

Remarks Controls yellow nutsedge. May be applied as a postemergence broadcast application or as a spot treatment. A second spot treatment may be necessary to control yellow nutsedge. Use with a nonionic surfactant or methylated seed oil to maximize weed control efficacy.

Caution Do not apply more than 1.33 oz of Sandea per year. There are no grazing restrictions following Sandea applications. Forage preharvest interval is 37 days.

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

Chemical family Sulfonylurea

MCPA (several products)

Rate 1 to 1.85 lb ae/A (2.16 to 4 pints/A Shredder or other MCPA-4 formulations)

Time Apply to annual broadleaf weeds when small and actively growing. Spray perennials in early-bud to full-bloom stage and during regrowth in fall.

Remarks Controls certain annual broadleaf and perennial weeds in grass pastures.

Caution Do not graze dairy animals or meat animals intended for slaughter for 7 days after treatment. Preharvest interval is 21 days for hay. Do not use this treatment if alfalfa is present and desired. Do not use if temporary injury to clovers cannot be tolerated. Do not use on newly seeded areas until grass is well established. Do not use from early boot to milk stage if grass seed production is desired.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

metsulfuron (Escort XP and others)

Rate 0.06 to 0.6 oz ai/A (0.1 to 1.0 oz/A Escort XP)

Time Apply to actively growing weeds.

Remarks Consult labels, which differ significantly. Information for Escort XP is provided by supplemental labels (Section 2(ee) recommendation for pastures). Controls a wide range of broadleaf weeds. For best results, apply with a nonionic or silicone surfactant. No grazing restrictions for any livestock, including lactating animals, with application rates of 1 oz ai/A (1.67 oz/A) or less. Note restrictions on timothy, fescue, and ryegrass pastures. Note recropping intervals.

Caution Do not allow drift to desirable vegetation. Injures or kills desirable forbs. Do not apply more than 1.67oz/A of Escort XP per year.

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

Chemical family Sulfonylurea

pendimethalin (Prowl H2O)

Rate 1.0 to 4.0 lbs ai/A (1.1 to 4.2 quarts/A Prowl H2O)

Time Apply to established stands of cool season forage grasses or mixtures with alfalfa prior to germination of annual grass and broadleaf weeds in fall, winter or spring.

Remarks Controls dodder, most annual grasses, and certain broadleaf weeds as they germinate, but will not control established weeds. Application rate varies with soil texture. Chemigation applications are labeled.

Caution Sequential applications may be made, but do not apply more than 4.2 quarts/A per year. Refer to main labels for crop rotation restrictions. There are no harvest or grazing restrictions following applications to pure grass stands, but do not harvest or graze for 14 days following application to mixed stands of grasses and alfalfa.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

picloram (several products)

Rate 0.06 to 0.5 lb ae/A

Time Apply to established grasses when weeds are growing well.

Remarks To control many annual and perennial broadleaf weeds and woody plant species.

Caution A restricted-use herbicide. Legumes are highly sensitive to picloram.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

pyraflufen (Edict 2SC IVM)

Rate 0.001 to 0.005 lb ai/A (1.0 oz/A to 3.5 oz/A Edict 2SC IVM)

Time Apply to broadleaf seedling weeds that are less than 4 inches tall or less than 3 inches in diameter if in the rosette stage. Thorough, uniform spray coverage is essential for good control of broadleaf weeds.

Remarks For postemergence broadleaf weed control in improved pastures. May be tank mixed with the synthetic auxin herbicides to broaden the weed control spectrum. Always apply with a methylated seed oil or nonionic surfactant at a rate of 0.5% v/v for optimum activity.

Caution Do not exceed two applications per season. Allow a minimum of 14 days between applications. Do not apply more than 7 oz/A per season. Livestock may graze treated area as soon as foliage is dry after application.

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

Chemical family Phenylpyrazole

quinclorac (Paramount)

Rate 0.14 to 0.75 lb ai/A (3 to 16 oz/A Paramount)

Time For the control and suppression of broadleaf perennial weeds and some broadleaf annual species. For field bindweed control apply in fall, but before a killing frost. Field bindweed should be actively growing and at least 4 inches long. Repeat applications are necessary to maintain adequate control.

Remarks May be used on Kentucky bluegrass, orchardgrass, annual and perennial ryegrass, and fine and tall fescue pasture mixes as well as other cool season grasses listed on the label. Adequate soil moisture and/or light rain after application is required for root uptake. Adding methylated seed oil or crop oil concentrate is required for consistent control. Nitrogen solutions or ammonium sulfate can be added to enhance control but should not replace the MSO or COC.

Caution Do not harvest treated area for hay within 7 days of treatment.

Site of action Group 4: synthetic auxin

Chemical family Quinoline carboxylic acid

saflufenacil (Sharpen)

Rate 0.022 to 0.045 lb ai/A (1 to 2 fl oz/A Sharpen)

Time Apply only to established stands (defined as grass planted in fall or spring that has gone through a first cutting/mowing) of perennial cool-season forage grasses to control annual broadleaf weeds.

Remarks A methylated seed oil is required for maximum efficacy. See Sharpen label for more information on adjuvants and tank-mixes. There are no grazing or feeding restrictions following applications of Sharpen.

Caution Do not exceed 6 fl oz/A per year. Sharpen may cause transitory injury to forage grasses (leaf necrosis) under certain conditions, but new growth is normal and vigor is not reduced. Sharpen will severely injure or kill some desirable broadleaf forages including clovers.

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

Chemical family Pyrimidindione

sulfosulfuron (Outrider)

Rate 0.035 to 0.062 lb ai/A (0.75 to 1.33 oz/A Outrider)

Time Apply postemergence in the spring or fall to actively growing weeds.

Remarks Controls select annual grasses and a range of broadleaf weeds. Review label for list of weed species controlled and information on grass species selectivity. Always apply Outrider with a nonionic surfactant. There are no grazing restrictions for any livestock, but for best weed control efficacy do not mow or graze the treated pasture for 2 weeks prior to or after application.

Caution This product is selective in crested wheatgrass, and selectivity in other pasture grasses is increased when they are not actively growing. If concerns exist about selectivity on desirable pasture grasses, a small area of the pasture should be treated to confirm selectivity prior to treating entire pasture.

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

Chemical family Sulfonylurea

triasulfuron (Amber)

Rate 0.21 to 0.42 oz ai/A (0.28 to 0.56 oz/A) Amber

Time Apply preemergence (for partial control of downy brome and cheat at the 0.56-oz/A rate) or postemergence to actively growing weeds.

Remarks Controls a wide range of broadleaf weeds when tank mixed with herbicides having another mode of action. See Amber label for tank-mix recommendations for specific weed species. For best postemergence application results, apply with a nonionic surfactant.

Caution See label for list of tolerant forage grass species. Orchardgrass, red fescue (fine fescues) and ryegrasses are likely to be injured by Amber. In general, apply to only tolerant grasses which have been established for at least 60 days. Amber Injures or kills desirable forbs including broadleaf forage species, such as clovers and alfalfa. There are no grazing restrictions, but do not harvest treated areas as hay for 30 days following applications of Amber.

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

Chemical family Sulfonylurea

triclopyr (several products)

Rate 0.75 to 2 lb ae/A (1 quart to 0.66 gal/A product)

Time Apply to grass pastures when broadleaf weeds and woody plants are actively growing.

Remarks Adjust rate for type of vegetation to be controlled. Controls both emerged herbaceous and woody broadleaf plants. To control biennial thistles or other biennial species, apply before flower stalks appear. Add an approved nonionic surfactant to the spray mix.

Caution Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not allow grazing or harvest green forage for lactating dairy animals from treated areas during the same growing season after application. Withdraw livestock from grazing treated grass at least 3 days before slaughter during the season of application. Preharvest interval is 14 days for hay.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

triclopyr + 2,4-D (Crossbow and others)

May not be applied to forage that will be cut and sold for commercial purposes

Rate 1% to 1.5% solution for spot treatments or up to 1 gal/A, depending on target weeds.

Time Apply to grass pastures when broadleaf weeds are actively growing.

Remarks May not be applied to forage that will be cut and sold for commercial purposes. Controls many broadleaf weeds. The smaller the annual weeds, the easier they are to control. Spray biennial weeds in the seedling to rosette stage, before flower stalks are apparent. This herbicide mixture is also very effective on a number of woody species.

Caution Do not allow to drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Note restrictions on label, particularly for grazing lactating dairy cattle, and for overseeding or reseeding.

Site of action (both) Group 4: synthetic auxin

Chemical family (triclopyr) pyridine; (2,4-D) phenoxy acetic acid