2,4-D (several products)
Rate 0.475 to 2 lb ae/A
Time Spray when annual weeds are small and actively growing. Treat perennial weeds at the specific growth stage(s) described on the label.
Remarks Controls many annual, biennial, and perennial broadleaf weeds in rangeland and grass pastures. Also controls or suppresses certain brushy species, including sagebrush, rabbitbrush, manzanita, and some chaparral species. Deep-rooted perennial weeds and woody plants usually require repeated applications for maximum control. See specific product label for rates for various weed species and for proper application timing. Multiple forms of 2,4-D are currently available, including choline, acid, amine, and ester salts. Different formulations vary substantially in volatility and risk for off-site vapor movement. Relative volatility risks are: very low (choline and acid formulations), low (amine) and high (ester, including 'low volatility' esters, which are only low volatility relative to now-obsolete and extremely volatile historic formulations of 2,4-D). Use choline or acid formulations in proximity to sensitive sites or crops, particularly during warm temperatures. Use of 2,4-D is tightly regulated during much of the growing season in many counties in eastern Washington. See product labeling and retail support for details on particular products. 2,4-D is premixed with additional active ingredient(s) in several products registered for range and pasture. See table of premix products at end of section for more details.
Caution Do not apply if spray drift may contact nearby crops or desirable plants or contaminate water for irrigation or domestic use. Do not graze meat animals within 3 days of slaughter. Do not graze dairy animals within 7 days after application. Do not cut hay within 30 days after application. Do not use on bentgrass, alfalfa, clover or other legumes, or on newly seeded pasture. When grass seed production is desired, do not apply after heading begins or when grass is in the boot to milk stage. Kills legumes.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic acid
aminopyralid (Milestone, Whetstone)
Rate 0.0.05 to 0.11 lb ae/A (3 to 7 oz/A Milestone)
Time Apply postemergence to actively growing plants or in the fall over senesced Russian knapweed plants or preemergence or postemergence for marestail control.
Remarks Controls a range of broadleaf weeds, including many in the sunflower and legume families. No restrictions on grazing or hay harvest. Surfactants have similar effects in combination with aminopyralid. Generally less injurious to desirable forbs than other synthetic auxin herbicides. Aminopyralid is premixed with additional active ingredient(s) in several products registered for range and pasture. See table of premix products at end of section for more details.
Caution Do not exceed a total of 0.11 lb ae/A (7 oz/A of Milestone) per year. For spot treatments, aminopyralid may be applied at an equivalent broadcast rate of up to 0.22 lb ae/A (14 oz/A Milestone), but no more than 50% of an acre may be treated at this rate. Allow 3 days after grazing on aminopyralid-treated forage before moving grazing animals to areas with plants sensitive to aminopyralid. Do not use plant residues that were treated within 3 days before harvest for compost or mulch that will be applied to susceptible broadleaf plants. Hay cannot be moved off farm if treated with aminopyralid in the preceding 18 months, unless specifically permitted by supplemental labels; see label for details.
Site of action Group 4: synthetic auxin
Chemical family (aminopyralid) Pyridine; (2,4-D) Phenoxy acetic acid
aminopyralid + florpyrauxifen-benzyl (DuraCor)
Rate 1 oz ae/A aminopyralid + 0.01 oz ae/A florpyrauxifen-benzyl to 1.66 oz ae/A aminopyralid + 0.17 oz ae/A florpyrauxifen-benzyl (12 to 20 oz/A DuraCor). Recommended rate varies by target species and growth stage, see label for details.
Time Apply to small actively growing weeds for best results. Use higher rates for larger weeds or stressful conditions, and for improved soil residual persistence. Apply only to well-established perennial grasses, some species may be tolerant to earlier applications, see label for full details.
Remarks Florpyrauxifen-benzyl improves control of several species not well controlled by aminopyralid alone (Milestone), and increases soil residual. Can be used to treat terrestrial weeds up to the water's edge and in some seasonally dry wetland sites, see label for full restrictions.
Caution Do not apply more than 20 oz/A DuraCor per year. Spot treatments may be made at up to twice this rate, provided no more than 50% of an acre is treated at the higher rate. Do not make more than 2 applications per year, or re-treat within 30 days. Do not transfer animals fed on treated grasses to areas in which sensitive broadleaf crops may occur without a 3-day waiting period on untreated pasture. Both active ingredients can accumulate and persist in manure and damage sensitive plants for years after application. See label for full restrictions on use and movement of manure when animals are fed treated forages. Do not use grasses treated with aminopyralid + florpyrauxifen in the preceding 18 months for hay intended for export outside the US. Unless specifically allowed by supplemental labelling, the following uses of hay treated within the preceding 18 months are prohibited: distribution or sell off of the farm or ranch where harvested; use in silage, haylage, baleage and/or green chop; use of hay or manure from animals fed treated hay in compost; and use of treated grasses for seed production. Do not use where damage to legumes or other desirable broadleaves cannot be tolerated. Do not rotate to any crop for at least 1 year after application, restrictions vary slightly between products. See label for specifics.
Site of action (both) Group 4: synthetic auxin
Chemical family (both) Pyridine
aminopyralid + florpyrauxifen-benzyl (TerraVue)
Rate 0.18 oz ae/A aminopyralid + 0.02 oz ae/A florpyrauxifen-benzyl to 0.26 oz ae/A aminopyralid + 0.24 oz ae/A florpyrauxifen-benzyl (2 to 2.85 oz/A TerraVue). Recommended rate varies by target species and growth stage. See label for details.
Time Apply to small actively growing weeds for best results. Use higher rates for larger weeds or stressful conditions, and for improved soil residual persistence. Apply only to well-established perennial grasses, some species may be tolerant to earlier applications. See label for full details.
Remarks Florpyrauxifen-benzyl improves control of several species not well controlled by aminopyralid alone (Milestone), and increases soil residual. Can be used to treat terrestrial weeds up to the water's edge and in some seasonally dry wetland sites. See label for full restrictions.
Caution Do not apply more than 2.85 oz/A TerraVue per year unless attempting total vegetation control and then do not apply more than 5.7 oz/A TerraVue per year. If spot treatment is needed after a broadcast application, wait at least 30 days and spot treatment can be 2 to 5.7 oz/A TerraVue provided no more than 50% of an acre is treated at this higher rate. Do not transfer animals fed on treated grasses to areas in which sensitive broadleaf crops may occur without a 3-day waiting period on untreated pasture. Both active ingredients can accumulate and persist in manure and damage sensitive plants for years after application. See label for full restrictions on use and movement of manure when animals are fed treated forages. Do not use grasses treated with aminopyralid + florpyrauxifen in the preceding 18 months for hay intended for export outside the US. Unless specifically allowed by supplemental labelling, the following uses of hay treated within the preceding 18 months are prohibited: distribution or sell off of the farm or ranch where harvested; use in silage, haylage, bailage and/or green chop; use of hay or manure from animals fed treated hay in compost; and use of treated grasses for seed production. Do not use where damage to legumes or other desirable broadleaves cannot be tolerated. Do not rotate to any crop for at least 1 year after application, restrictions vary slightly between products. See label for specifics.
Site of action (both) Group 4: synthetic auxin
Chemical family (both) Pyridine
aminopyralid + metsulfuron (Chaparral)
Rate 1 to 3.3 oz/A
Time Apply postemergence to actively growing plants or in the fall over senesced Russian knapweed plants or preemergence or postemergence for marestail control.
Remarks Controls a range of broadleaf weeds, including many in the sunflower and legume families. In general,
2 oz/A controls most pasture weeds with lower rates (< 2 oz/A) effective on annual weeds and higher rates (>2 oz/A) effective on woody weeds. No restrictions on grazing or hay harvest. Surfactants have similar effects in combination with aminopyralid.
Caution Do not exceed 3.3 oz/A of Chaparral in 1 year. Allow 3 days after grazing on Chaparral-treated forage before moving grazing animals to areas with plants sensitive to aminopyralid. Do not use plant residues that were treated within 3 days before harvest for compost or mulch that will be applied to susceptible broadleaf plants.
Site of action aminopyralid Group 4: synthetic auxin; metsulfuron-methyl Group 2: acetolactate synthase (ALS) inhibitor
Chemical family (aminopyralid) Pyridine; (metsulfuron) Sulfonylurea
carfentrazone (Aim EC)
Rate 0.008 to 0.03 lb ai/A (0.5 to 2 oz/A Aim EC)
Time Apply postemergence to small (less than 4 inches tall) actively growing broadleaf weeds.
Remarks Controls corn spurry, a species not listed on many labels of herbicides used in pasture. Provides contact, foliar burndown activity of small broadleaf weeds only. Full coverage essential for good activity. Use of nonionic surfactant (NIS), crop oil concentrate (COC), or methylated seed oil (MSO) is required. Inclusion of a liquid sprayable nitrogen fertilizer at 2 to 4% v/v or ammonium sulfate at 2 to 4 lb per acre is allowed and recommended for best activity. For optimal control, especially of larger weeds, tank mix with a systemic herbicide.
Caution No preharvest interval required. Allow at least 7 days between applications. Do not exceed three applications or 0.093 lb ai/A (5.9 oz/A Aim) per season.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Triazinone
chlorsulfuron (Telar XP)
Rate 0.01 to 0.06 lb ai/A (0.25 to 1.33 oz/A Telar XP)
Time For perennial weeds, apply at budding or flowering stage or in fall at rosette stage. Apply early in life cycle of annual weeds.
Remarks Bluegrass, bromes, orchardgrass, and wheatgrasses tolerate rates of 0.25 to 1 oz/A. Fescue, bluestems, lovegrasses, and wild rye tolerate rates of 0.25 to 0.5 oz/A. Apply only to established grasses. Perennial grasses vary in their tolerance to chlorsulfuron; see label for species-specific tolerances and recommended rates, and for reseeding intervals. Chlorsulfuron applied before flowering can reduce seed head development of cool-season grasses. Chlorsulfuron is premixed with additional active ingredient(s) in several products registered for range and pasture. See table of premix products at end of section for more details.
Caution Stressed grasses may be injured. No grazing or harvest restrictions for applications up to 0.06 lb ai/A (1.33 oz/A Telar XP). Do not exceed 0.047 lb ai/A (1 oz/Ac Telar XP) in a single application. Do not make more than 3 separate applications per acre per year, or apply with less than 14 days between applications. Do not exceed 0.06 lb ai/A (1.33 oz/A Telar XP) per year. Incompatible with most desirable broadleaf species. Clean sprayer per label instructions immediately after spraying, and/or at the end of every day.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
clopyralid (Stinger, Transline, several others)
Rate 0.12 to 0.5 lb ae/A (0.33 to 1.33 pints/A Transline)
Time Apply to young, actively growing weeds. Established grasses are tolerant. Apply to Canada thistle after most basal leaves have emerged but before bud stage, or to fall regrowth following first light frost of the season. Apply to diffuse and spotted knapweeds from mid bolt to late bud stage, to Russian knapweed from bud to mid flower, and to yellow starthistle from rosette to mid-bolting.
Remarks May be tank mixed with 2,4-D for expanded spectrum of activity. Grasses may be planted any time after application. Clopyralid is premixed with additional active ingredient(s) in several products registered for range and pasture. See table of premix products at end of section for more details.
Caution Apply only once in a 12-month period. Do not allow drift to crops. Do not spray pastures if forage legume component is desired. See label restrictions on planting crops into treated areas, and for restrictions on treating grass hay for international export. Before moving livestock from treated site into sensitive crop areas, allow 7 days of grazing on an untreated pasture.
Site of action Group 4: synthetic auxin
Chemical family Pyridine
clopyralid + 2,4-D (Curtail)
Rate 2 to 4 quarts/A
Time Apply when weeds are young and actively growing.
Remarks Use 2 quarts/A on light to moderate infestations of Canada thistle and knapweeds (spotted and diffuse) in good growing conditions. Use 3 quarts/A for dense infestations or under poor growing conditions. On Russian knapweed, use 3 to 4 quarts/A.
Caution Do not plant grasses for 30 days after application. Do not use on newly seeded grass areas until grass is well established. Do not use on bentgrass. Do not spray pastures containing desirable forbs, especially legumes, unless injury can be tolerated. Do not use hay or straw from treated area for composting or mulching on susceptible broadleaf crops. Do not graze dairy cattle in treated area for 14 days after application. Remove meat animals from area 7 days before slaughter if pasture was treated less than 2 weeks earlier. Do not cut for hay within 30 days after application. Do not use straw or manure from treated areas for compost or mulch.
Site of action (both) Group 4: synthetic auxin
Chemical family (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
dicamba (Clarity, Vanquish, several others)
Rate 0.25 to 1 lb ae/A, depends on weed species and growth stage.
Time Apply after weeds emerge. Treat annuals when small and actively growing. See label for proper timing and rates on perennials.
Remarks Controls many annual, biennial, and perennial broadleaf weeds and many woody brush and vine species. Rate depends on weed species and growth stage at time of treatment; see label for specifics. Can be applied using water, oil-water emulsions, or sprayable fluid fertilizer as the carrier. May also be applied as a cut-surface treatment to control unwanted trees or to prevent sprouts on cut trees. Formulations of dicamba currently registered in rangeland have significant potential for volatilization and off site movement. Use appropriate caution in proximity to sensitive sites or crops, particularly during high temperatures. Use of dicamba is tightly regulated during much of the growing season in many counties in eastern Washington. See product labeling and retail support for details on managing volatility risk. Dicamba is premixed with additional active ingredient(s) in several products registered for range and pasture. See table of premix products at end of section for more details.
Caution No waiting period between treatment and grazing non-lactating animals (see label for timing restrictions on dairy animals). Meat animals must be removed from treated areas 30 days before slaughter. Rates over 2 lb ai/A may temporarily injure many grass species. Newly seeded grasses (see label) may be injured at rates exceeding 0.75 lb ae/A. Do not exceed 8 lb ae/A per season. Kills legumes.
Site of action Group 4: synthetic auxin
Chemical family Benzoic acid
dicamba + 2,4-D (Weedmaster or Pasturemaster)
Rate 0.5 to 4 pints product/A
Time When weeds are actively growing.
Remarks For pasture, range, and non-cropland. Spot spraying rates can go as high as 6 pints/A; see label for weeds controlled at higher rates.
Caution Do not apply when grass is in boot stage. See label for grazing restrictions.
Site of action (both) Group 4: synthetic auxin
Chemical family (dicamba) benzoic acid; (2,4-D) phenoxy acetic acid
dicamba + diflufenzopyr (Overdrive, Distinct)
Rate 0.125 to 0.25 lb ae dicamba + 0.05 to 0.1 lb/A diflufenzopyr (4 to 8 oz/A Overdrive)
Time Apply postemergence to actively growing plants. May also be applied to Russian knapweed in the fall over senesced plants. May be applied pre- or post-emergence for marestail control.
Remarks Controls a range of broadleaf weeds with lower rates used on annual weeds and higher rates on perennial weeds. Will injure desirable legumes. Use a nonionic surfactant or methylated seed oil. Diflufenzopyr can complement the activity of other synthetic auxin herbicides when tank mixed, See label for specific recommendations.
Caution Do not exceed 0.25 lb ae dicamba + 0.1 lb ae diflufenzopyr per acre (8 oz/A of Overdrive) per season. Do not plant any crop for 30 days after application. Grazing is allowed immediately after application.
Site of action (dicamba) Group 4: synthetic auxin; (diflufenzopyr) Group 19; auxin transport
Chemical family (dicamba) benzoic acid; (diflufenzopyr) semicarbazone
fluroxypyr (Vista XRT, Starane Ultra, several others)
Rate 0.13 to 0.5 lb ae/A (6 to 23 oz/A Vista)
Time Apply after weeds emerge and during period of active growth prior to bud stage.
Remarks Apply to established grasses and to new plantings that are in the two-true-leaf to boot stage of growth. Rates and allowed use sites vary between specific products. Consult specific labels to confirm. Fluroxypyr is premixed with additional active ingredient(s) in several products registered for range and pasture. See table of premix products at end of section for more details.
Caution No grazing restrictions for livestock, including lactating dairy animals. Preharvest interval for forage is 7 days. Do not feed treated forage for 2 days before slaughter for meat. Split applications may be made in a single year, provided maximum application rate is not exceeded. Do not exceed 0.5 lb ae fluroxypyr/A (23 oz/A Vista XRT) per year. May injure legumes and other broadleaf plants.
Site of action Group 4: synthetic auxin
Chemical family Pyridine
fluroxypyr + picloram (Surmount)
Rate 1.5 to 2.5 pints/A (herbaceous) or 3 to 4 pints/A (woody)
Time Apply after weeds emerge. Apply low rate to actively growing, small weeds and up to 2 pints/A when weeds are dense or not growing well.
Remarks If applying before seeding new grass, wait 3 weeks before seeding. To new plantings, apply after grasses are tillering.
Caution Not registered for use in Oregon. Lactating dairy animals may not graze or be fed treated forage for 14 days after application. Do not feed treated forage for 3 days before slaughter for meat. No other livestock restrictions. Preharvest interval for hay is 7 days.
Site of action (both) Group 4: synthetic auxin
Chemical family (both) pyridine
fluroxypyr + triclopyr (PastureGard)
Rate 1.5 to 3 pints/A (herbaceous) or 3 to 8 pints/A (woody)
Time Apply after weeds emerge and are still small, not after flower bud stage. Apply low rate to actively growing annual weeds and apply 2 to 3 pints/A to biennial or perennial weed species.
Remarks Do not use on bentgrass. Wait at least 3 weeks after application to reseed. Apply to new plantings after grasses are tillering.
Caution Do not exceed 8 pints/A in one growing season. Do not feed treated forages to lactating animals during the season of application. Do not feed treated forages for 3 days before slaughter for meat. Preharvest interval for hay is 14 days.
Site of action (both) Group 4: synthetic auxin
Chemical family (both) pyridine
glyphosate (several products)
Rate 0.1875 to 3.75 lb ae/A
Time Annual weeds are best controlled when small and actively growing. Apply to actively growing perennial weeds at or beyond full flower. Results are best if applied in late summer or fall after fruit forms. Fall treatments must be before a killing frost.
Remarks Controls many annual and perennial weed species before renovating pastures. Rates depend on weed species, stage of growth, and density. Repeat treatments may be necessary to control weeds regenerating from underground parts or seed. May also be applied as a spot treatment or by wiper application to established pastures, but do not treat more than 10% of any acre at one time. Further applications may be made to the same area at 30-day intervals. Some glyphosate products are labelled for control of weeds in and around water and riparian areas; check specific labels for permissible uses and restrictions. Low rates of glyphosate can be applied during winter dormancy period of desirable perennials for control of cheatgrass and other winter annual grasses in some situations. See label for details.
Caution A nonselective herbicide that kills plants on contact with green tissue. Total treatments must not exceed 8 lb ai/A per year. Remove domestic livestock before application. Grazing and harvest restrictions vary by formulation; check product label for specific restrictions.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
halosulfuron (Sandea, several others)
Rate 0.03 to 0.06 lb ai/A (0.67 to 1.33 oz/A Sandea).
Time Postemergence to small weeds. See label for specific size recommendations per weed species.
Remarks For control of sedges (especially yellow nutsedge) and some broadleaf weeds in established grasses in range and pastures. Use of nonionic surfactant is recommended.
Caution Do not make more than 2 applications or apply more than 0.06 lb ai/A (1.33 oz/A Sandea) in a 12-month period. Spot treatments are limited to a rate of 0.75 oz/A per application, but 2 sequential spot applications may be made, treating only emerged sedges each time. No pre-grazing or pre-slaughter waiting period, including for lactating animals. Wait 37 days before mechanical harvest of treated forages.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
hexazinone (Velpar DF VU, several others)
Rate Individual stem basal soil applications, up to maximum per-acre rate of 0.67 lb ai/A per year.
Time Apply to undesirable brush and woody plants from late winter through summer, pre-budbreak until new growth hardens off.
Remarks For control of herbaceous and woody weeds in range and pastures with basal directed applications only.
Caution Apply only as basal stem applications using exact-delivery handgun applicator. See specific product label for application directions and use restrictions. Injury to desirable trees or other plants may result if chemical is washed or moved into contact with their roots. Do not apply to frozen soils. No grazing or harvest restrictions when applied as basal soil application.
Site of action Group 5: photosystem II inhibitor
Chemical family Triazinone
imazapic (Plateau, Panoramic, several others)
Rate 0.0312 to 0.1874 lb ai/A (2 to 12 oz/A Plateau); see label for specific recommendations by weed species.
Time Annual weeds may be treated preemergence or early postemergence. Most reliable control of problematic winter annual grasses (cheatgrass, medusahead, ventenata, etc.) is obtained by early post-emergence applications made at the 1-to 2-leaf stage when adequate soil moisture is present and plants are actively growing. Apply to actively growing perennial weeds at or beyond full flower. Results are best if applied in late summer or fall after fruit forms. Leafy spurge can be sprayed before the latex stops flowing in fall (test by breaking open a stem to see whether latex will ooze from the wound). Russian knapweed and Dalmatian toadflax can be controlled in late fall.
Remarks Spray adjuvant required for post-emergence applications. A combined surfactant + methylated seed oil provides best activity, but may increase potential for injury of vulnerable perennial grasses; see label for specific details. Rates vary by weed to be controlled and tolerance of desirable perennials present; see label for specifics. Generally, use lower rates (4 to 6 oz/A Plateau) for early-season annual weed control. Higher rates (8 to 12 oz/A Plateau) applied in late summer or fall are needed to control leafy spurge. Fall to early winter application at rates above 0.125 lb ai/A (8 oz/A Plateau) may injure establishing perennial grasses.. Perennial grasses and forbs are known to vary considerably in their tolerance to imazapic at both seedling and established stages. See label for listing of tolerance ranges for specific species.
Caution Do not cut hay for 7 days after application. Do not exceed 0.1875 lb ai/A (12 oz/A Plateau) in a calendar year. Do not rotate treated pastures into crop production for 12 to 48 months depending on rate. See specific label for details.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Imidazolinone
imazapyr (Arsenal, several others)
Rate For spot treatment only. Do not treat more than 10% of available area to be grazed or cut for hay. Apply 0.03 lb ae/Ac to 0.75 lb ae/A imazapyr (48 oz/A Arsenal)
Time Apply to small, actively growing weeds.
Remarks An adjuvant is required, nonionic surfactant (NIS), methylated seed oil (MSO) or silicone-based surfactant are all permissible. Invert emulsions can be used also. Has activity on many problematic weeds. Several formulations are labelled for use in certain riparian and aquatic sites; see specific labels for details. Many formulations are also labelled for single stem application to problematic woody species (cut stump and injection methods).
Caution Do not treat more than 10% of available area to be grazed or hayed. Do not apply more than 0.75 lb ae per acre per year. No grazing restrictions following application; do not cut forage grass for hay for 7 days after application. Do not plant rotational crops for 12 month following application, plus successful completion of field bioassay.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Imidazolinone
indaziflam (Rejuvra)
Rate Grazed areas 0.046 to 0.065 lb ai/A (3.5 to 5 oz/A Rejuvra); areas not grazed or cut for hay 0.046 to 0.09 lb ai/A (3.5 to 7 oz/A Rejuvra). Use lower rates only where weed pressure is light and shorter period of residual activity is desired.
Time Apply at least several weeks prior to expected germination of targeted weeds. Apply to dry soils when rain is not expected for at least 48 hr. Can be successfully applied several months in advance of weed germination.
Remarks Indaziflam provides multiple years of pre-emergent control of germinating seeds of most species from a single application. Provides excellent control of winter annual grass weeds (e.g., cheatgrass, medusahead, feral rye, etc.). Indaziflam is safe over the top of most well-established perennial grasses, but see label for full details. Use only in areas in which desirable perennial grass stands are of adequate density to meet management goals for several years after application without any further plant recruitment. Do not expect to conduct successful seedings of desirable plants for several years after application. Pre-emergent activity only, use appropriate tank-mix partners if weeds have emerged prior to application. Does not control established perennial weeds.
Caution Adequate binding time on dry soil reduces risk of indaziflam moving into the root zone of desirable plants. Do not apply to or around water. Do not apply to saturated, frozen, or snowcovered ground. Do not harvest hay within 40 days of application. Do not exceed a maximum rate of 0.065 lb ai/A (5 oz/A Rejuvra) in a single application. On grazed areas, do not apply more than 0.078 lb ai/A (6 oz/A Rejuvra) in a 12-month period. Do not make more than 2 applications in a 12-month period. Allow at least 60 days between applications.
Site of action Group 29, inhibition of cellulose biosynthesis
Chemical family Alkylazine
MCPA ester (Rhonox, several products)
Rate 0.46 to 0.1.39 lb ae/A
Time Apply to annual broadleaf weeds when small and actively growing. Spray perennials in early-bud to full-bloom stage and during re-growth in fall.
Remarks Controls certain annual broadleaf and perennial weeds in grass pasture and rangeland, including hoary cress, and buttercup (multiple applications may be required for buttercup control).
Caution Do not apply more than a total of 1.5 lb ae/A per year. Do not apply more than 2 applications per year, with minimum reapplication interval of 21 days. Use of MCPA is tightly regulated during much of the growing season in many counties in eastern Washington. Do not graze for 7 days after treatment. Do not use this treatment on desirable alfalfa. 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 where grass seed production is desired.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic acid
metsulfuron (Escort XP, several others)
Rate 0.00375 to 0.0625 lb ai/A (0.1 to 1.67 oz/A Escort XP), depends on use site
Time Apply postemergence to actively growing weeds.
Remarks Controls a wide range of broadleaf weeds. For best results, use a nonionic or organosilicone surfactant. Use 0.00375 lb ai/A (0.1 oz/A Escort XP) for grass establishment and on seedling grasses, and rates of 0.012 to 0.0625 lb ai/A (0.33 to 1.67 oz/A Escort XP) for established grasses. Metsulfuron is premixed with additional active ingredient(s) in several products registered for range and pasture. See table of premix products at end of section for more details.
Caution Consult labels for each product; labels differ significantly. Perennial grass species vary in their tolerance to metsulfuron, see label for specific cautions and restrictions for use and for replanting intervals. Note recropping restrictions on label. No grazing restrictions at rates less than 0.0625 lb ai/A (1.67 oz/A Escort XP). Do not apply more than 0.0625 lb ai/A (1.67 oz/A Escort XP) per year on pasture, rangeland, or CRP. Metsulfuron is not safe for legumes or broadleaf plants. Rotation intervals to crop production can be lengthy, see label for specific crop information.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
metsulfuron-methyl + dicamba + 2,4-D (Cimarron Max)
Rate 0.25 oz/A metsulfuron-methyl + 1 pint/A dicamba + 2,4-D to 1 oz/A metsulfuron-methyl + 4 pints/A dicamba + 2,4-D. The label tells how to select the use rate, given weed spectrum and sizes.
Time Apply pre- or post-emergence. Results are best if applied to young, actively growing weeds.
Remarks Cimarron Max is a co-pack with two components: 1) metsulfuron-methyl and 2) a combination of dicamba and 2,4-D at 1 lb ai/gal dicamba and 2.87 lb ai/gal 2,4-D.
Caution Weeds often are less susceptible after exposure to cold weather or drought.
Site of action (metsulfuron-methyl) Group 2: acetolactate synthase (ALS) inhibitor; (dicamba and 2,4-D) Group 4: synthetic auxin
Chemical family (metsulfuron-methyl) Sulfonylurea; (dicamba) Benzoic acid; (2,4-D) Phenoxy acetic acid
pendimethalin (Prowl H2O, Satellite Hydrocap)
Rate 1 to 4 lb ai/A (1.1 to 4.2 quarts/A Prowl H2O)
Time Apply prior to emergence of target weed(s).
Remarks Controls many annual grasses and broadleaf weeds as they germinate. Apply only to established grasses with more than 6 tillers per plant.
Caution Do not apply more than 4.2 quarts/A per year. May be applied in a single application or in sequential applications made 30 or more days apart. There is no preharvest or grazing interval for grass stands treated with Prowl H20, other labels may differ. Do not graze or harvest for hay mixed stands of alfalfa/cool-season grasses within 14 days of treatment. Do not apply to mixed stands of cool-season grasses and legumes other than alfalfa. Do not apply if surface water is present in field.
Site of action Group 3: microtubule assembly
Chemical family Dinitroaniline
picloram (Tordon 22K, several others)
Rate 0.125 to 1 lb ae/A (8 to 64 oz/A Tordon 22K). Maximum allowable rate varies by application method and targeted weed,
Time Treat when weeds are growing actively, in the spring before full bloom, or in late summer or fall. Re-treat in subsequent years as needed.
Remarks Controls many troublesome perennial and woody weed species including thistles, yellow starthistle, leafy spurge, knapweeds, field bindweed, rabbitbrush, rush skeletonweed, and poison-oak. Rates depend on weed species and plant density. Do not apply at over seasonal maximum rate, which varies by application method and targeted weed; see specific product label for full restrictions. Not compatible with legumes or other desirable broadleaf plants. Applicators using backpack or other handheld equipment often inadvertently apply well over the intended, labeled rate of this product when spot-treating scattered plants or small patches of broadleaf weeds. When this occurs, perennial grasses may be severely damaged or killed in over-treated patches, and injury can persist for many years after treatment. Take particular care to avoid this when spot applying - calibrate equipment and do not spray past the point of leaf wetting. Picloram is premixed with additional active ingredient(s) in several widely used products registered for range and pasture. See table of premix products at end of section for more details.
Caution Most formulations are restricted-use herbicides. Do not apply on or near susceptible crops or desirable plants. Buffer zone restrictions, air temperature limits, and grazing restrictions are required. Do not contaminate water or use where surface water from treated areas can run off to adjacent cropland. Do not apply to inner bank or bottom of irrigation ditches. Do not apply to snow or frozen ground. Do not use in surface irrigated or sub-irrigated areas, areas subject to frequent flooding, or with shallow water table. Do not allow grazing in areas where poisonous plants were sprayed until plants have died - herbicide may increase palatability. Do not spray pastures if the forage legume component is desired. Do not move treated soil. Do not transfer livestock onto crop areas for at least 7 days after grazing on land treated with picloram. See label for other grazing restrictions.
Site of action Group 4: synthetic auxin
Chemical family Pyridine
pyraflufen-ethyl (Venue)
Rate 0.0026 to 0.0046 lb ai/A (2 to 3.5 oz/A Venue)
Time Apply postemergence to small (less than 4 inches tall) actively growing broadleaf weeds.
Remarks Provides contact, foliar burndown activity of small broadleaf weeds only. Full coverage essential for good activity. Use of a crop oil surfactant required for best weed control. For optimal control, especially of larger weeds, tank mix with a systemic herbicide.
Caution Livestock may graze as soon as spray dries. Allow at least 14 days between applications. Do not apply more than 0.0046 lb ai/A (3.5 oz/A Venue) in a single application. Do not exceed two applications or exceed 0.093 lb ai/A (7 oz/A Venue) per season. Maximum 30 day rotational restriction to any crop.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Triazinone
quinclorac (Facet L, several others)
Rate 0.14 to 0.75 lb ae/A (12 to 64 oz/A Facet L)
Time Apply to emerged, actively growing weeds. For field bindweed, apply in the fall just prior to first killing frost.
Remarks Good activity on field bindweed relative to most other options. Controls or suppresses a number of other broadleaf and some grass weeds. Suppresses leafy spurge. For control of bindweed and other difficult perennial weeds, apply to at least 4" of green fall regrowth just prior to the first killing frost of the season. Continued annual applications will be necessary to maintain bindweed control.
Caution Do not cut treated forages for hay within 7 days of application. Do not apply to water or areas with surface water present. Do not apply to irrigation ditches or areas that act as a channel for water entering cropland. Do not apply more than 0.75 lb ae/A per year (64 oz/A Facet L).
Site of action Group 4: synthetic auxin
Chemical family Quinoline-carboxylate
rimsulfuron (Laramie 25DF, several others)
Rate 0.047 to 0.0625 lb ai/A (3 to 4 oz/A Laramie 25DF)
Time Apply in fall or spring outside times of usually frozen soil. If possible, apply so that 0.5 inch or more of precipitation occurs within 2 to 3 weeks of application.
Remarks For use in restoration of degraded rangelands severely infested with cheatgrass, medusahead, and certain other weeds. To release perennial grasses for site restoration in areas infested with downy brome or medusahead, apply in the fall no more than 6 weeks before the expected date of soil freezing. To prepare infested areas with inadequate perennial grass density for re-seeding, apply in the spring after soils thaw and at least 7 months prior to anticipated reseeding date. See label for compatible species and full details on reseeding interval. Rimsulfuron may cause injury to desired perennial grasses; see label for specifics.
Caution Requires continuous agitation to maintain suspension in spray tank. Failure to maintain agitation can result in dramatic over-or under-application, as well as sprayer plugging. Do not graze treated sites or cut for hay for at least 1 year after application. Deferment of grazing also allows time for establishment/recovery of desirable perennial grasses. Do not apply more than 0.0625 lb ai (4 oz/A Laramie 25DF) per acre per year. Clean spray equipment with ammonia immediately after application per label directions.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
propoxycarbazone (Lambient)
Rate 0.039 to 0.053 lb ai/A (0.9 to 1.2 oz/A Lambient). Use lower rate only for light weed infestations under favorable environmental conditions.
Time Apply early post-emerge to actively growing weeds in the fall or spring. Best control of cheatgrass, medusahead and other annual grass weeds will be obtained at 1 to 2 leaf stage. Larger grass weeds will likely be suppressed, not controlled.
Remarks Use nonionic surfactant (NIS) at 0.25 to 0.5 % v/v. A nitrogen fertilizer may also be included for best weed control. For weed control in established stands of perennial grasses, apply 0.053 lb ai/A (1.2 oz/A Lambient) in the fall when target weeds have emerged. Propoxycarbazone can cause stunting, injury, and/or seedhead suppression in established grasses. Grass species are known to vary in their tolerance to propoxycarbazone. See label for full details and recommendations. Where perennial grass stands include recently established plants, wait until seedlings have reached at least the 5 leaf stage, and expect that injury or thinning of seedling grasses is likely. For areas to be reseeded, wait at least 90 days after application before seeding desired perennial grasses. See label for known species sensitivities in reseeding.
Caution Not recommended for use in seed production of otherwise tolerant species. Do not apply more than 0.053 lb ai (1.2 oz/A Lambient) per acre per year. Do not cut treated hay within 7 days of application. Not safe for legumes.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Triazolinone
saflufenacil (Detail)
Rate Growing season: 0.022 to 0.044 lb ai/A (1 to 2 oz/A Detail); Dormant season: 0.022 to 0.089 lb ai/A (1 to 4 oz/A Detail)
Time Apply to small, broadleaf weeds during active growth or dormant season of perennial grasses.
Remarks Provides contact, foliar burndown activity of broadleaf weeds, and short-term soil residual activity at higher rates. Full coverage essential for good post-emergence control. Requires methylated seed oil (MSO) at 1% v/v; do not substitute other surfactants. Apply only to established perennial grasses. May cause transitory grass injury, but normal growth and vigor is not reduced under normal conditions.
Caution Do not apply more than 0.044 lb ai per acre per year for growing season applications, or 0.089 lb ai per acre per year for dormant season applications. Sequential applications may be made provided total seasonal limits are not exceeded, and applications are separated by at least 14 days. Dormant season sequential applications should be made in a fall/winter followed by early spring sequence.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family N-phenyl-imide
sulfosulfuron (Outrider)
Rate 0.035 to 0.062 lb ai/A (0.75 to 1.33 oz/A Outrider)
Time Apply in fall or spring to emerged, actively growing weeds. For cheatgrass control, apply at 1-to 2-leaf stage, application to larger cheatgrass plants will result in suppression only. Injury risk to desirable perennials is reduced if applied during periods when perennials are not actively growing.
Remarks Use higher rates if weeds are larger, and for best control of difficult species. Controls annual grasses and some annual forbs. Use nonionic surfactant at 0.25 to 0.5 % v/v (1 quart/100 gal).
Caution Outrider controls meadow foxtail. If meadow foxtail is an important forage grass, do not apply Outrider to areas where meadow foxtail is present. Perennial bromes can be reduced in the first season after application. Addition of spring nitrogen can reduce injury. Generally safe on perennial grasses, but can cause temporary stunting and chlorosis. If unsure about safety on desirable grass species, test on small area to confirm selectivity. Treated forage may be grazed immediately after application, but for best weed control, defer grazing for 2 weeks after application. Clean application equipment with 1% v/v ammonia solution immediately after application, see label for full details.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
tebuthiuron (Spike 20P)
Rate 0.5 to 4 lb ai/A (2.5 to 20 lb/A product)
Time May be applied any time. Best efficacy is obtained from applications made just prior to onset of fall/winter precipitation. Best safety on perennial grasses obtained from applications made during grass dormancy.
Remarks A surface applied, pelleted herbicide for control of woody vegetation, including sagebrush. May be applied as spot treatments, or broadcast. Treatments become effective after enough rain falls to move the chemical into the root zone where it is absorbed by target plants. Brush will continue to die for several months after application, and full control may take several years to achieve. For best efficacy, do not disturb treated plants by chaining, woodcutting, burning, etc. for 2 years after treatment. During this time woody plants may go through repeated cycles of leaf growth and defoliation. A single application is normally effective for several years. Areas treated may be overseeded with grass. Tebuthiuron will also control herbaceous broadleaf plants, including legumes.
Caution Do not apply tebuthiuron anywhere roots of desirable woody plants may be present. Do not exceed 2 lb ai/A (10 lb/A Spike 20P) if average annual precipitation is less than 20 inches, or more than 4 lb ai/A (20 lb/A Spike 20P) in areas with over 20 inches annual precipitation. Maximum use rate is 4 lb ai/A once every 3 years and no more than 2 treatments totaling 6 lb ai/A in any 6-year period. Tebuthiuron has potential to contaminate groundwater, and has many restrictions regarding movement to groundwater. Check label carefully to insure prohibited uses are avoided. May slightly and temporarily injure desirable grasses. Minimize injury by applying herbicide when grasses are dormant. Do not apply on field crops, near desirable trees or shrubs, or to areas into which their roots may extend. May seriously injure desirable forage legumes and other broadleaf plants. Rate and annual rainfall affect haying and grazing restrictions; see label. Contact retailer or Corteva representative for more details and assistance in label interpretation.
Site of action Group 7: photosystem II inhibitor
Chemical family Substituted urea
triasulfuron (Amber)
Rate 0.013 to 0.026 lb ai/A (0.28 to 0.56 oz/A Amber)
Time Apply postemergence to actively growing weeds. Apply preemergence for suppression of downy brome and cheat.
Remarks Perennial grasses vary in their tolerance to triasulfuron, consult label for specifics. Apply in a tank-mix with an appropriate herbicide having another mode of action to control a wide spectrum of broadleaf weeds. Nonionic surfactant (NIS) required for postemergent applications. Apply 0.026 lb ai/A (0.56 oz/A Amber) for prior to emergence for partial control of downy brome and cheat.
Caution Orchardgrass, red fescue, and ryegrasses will likely be injured by triasulfuron. Preharvest interval is 30 days for hay; grazing may occur immediately after application. Recropping restrictions are long for some situations. Do not apply more than 0.026 lb ai/A in a single application. Do not apply more than 0.0394 lb ai/A (0.84 oz/A Amber) total per acre per year. Do not make more than 2 applications per year. Minimum retreatment interval 60 days. Do not apply to seedling grasses for at least 60 days after emergence. Will severely injure legumes and other desirable broadleaf plants.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
triasulfuron + dicamba (Rave)
Rate 2 to 4 oz/A
Time Apply postemergence to actively growing weeds.
Remarks Add a nonionic surfactant to the spray mixture. Consult label for tolerant grasses.
Caution Wait 60 days after grasses emerge before applying Rave. Orchardgrass, red fescue, and ryegrasses will likely be injured. Clovers and alfalfa also may be injured. After applying, wait at least 30 days to cut for hay or to slaughter meat animals that were exposed, and wait at least 8 days to graze lactating cows.
Site of action (triasulfuron) Group 2: acetolactate synthase (ALS) inhibitor; (dicamba) Group 4: synthetic auxin
Chemical family (triasulfuron) Sulfonylurea; (dicamba) Benzoic acid
triclopyr (Remedy Ultra, Vastlan, Garlon XRT, several others.)
Rate 1 to 2 lb ae/A
Time Apply when woody plants and broadleaf weeds are actively growing. Apply to annual and biennial plants prior to bolting.
Remarks Controls both emerged herbaceous and woody broadleaf plants. including sulfur cinquefoil. Controls many trees, brush, and other woody plants (see label for basal, trunk, and cut stump application uses). Multiple formulations of triclopyr are registered for use in rangeland, including choline, amine, and ester salts, Most formulations are esters. Different forms vary substantially in volatility and risk for off-site vapor movement. Relative volatility risks are: very low (choline), low (amine) and high (ester). Select choline or amine formulations for use in proximity to sensitive sites or crops, particularly during warm temperatures. Triclopyr is premixed with additional active ingredient(s) in several products registered for range and pasture. See table of premix products at end of section for more details.
Caution Do not allow drift to desirable vegetation. Do not apply more than 2 lb ai/A in a growing season on rangeland. Desirable broadleaf plants will be seriously injured or killed. See specific product label for haying and grazing restrictions. Some formulations of triclopyr are labeled for aquatic, riparian, and wetland applications, see label and retailer or manufacturer for specifics. Permits are generally required for aquatic applications, and additional use restrictions generally apply to riparian and wetland applications.
Site of action Group 4: synthetic auxin
Chemical family Pyridine
triclopyr + 2,4-D (Crossbow)
Rate Spot treatment: use 1 to 1.5% mixture in water. Broadcast: up to 1.5 gal/A (3 lb ae of 2,4-D and 1.5 lb ae of triclopyr).
Time Postemergence, to actively growing plants.
Remarks Controls many woody plants as well as annual and perennial broadleaf weeds.
Caution No forage may be sold for commercial purposes.
Site of action (both) Group 4: synthetic auxin
Chemical family (triclopyr) pyridine; (2,4-D) phenoxy acetic acid
PREMIX PRODUCTS
There are a large number of premix products available for use in rangeland and pasture, including some of the most commonly used herbicides on the market. Manufacturers premix multiple active ingredients for many reasons, including:
Increased efficacy. Many active ingredients have good activity on a somewhat limited range of weed species, but by combining multiple active ingredients manufactures can achieve control of a large range of weeds with a single product. In other cases, particular active ingredients interact to provide synergistic activity, in which performance of the mixture is better than the simple sum of its parts.
Reduced Cost. Often, combining a slightly reduced rate of a high-performing but expensive active ingredient with a more economical tank mix partner can achieve the same weed control activity as either product used alone at higher rates, and in many cases at a lower overall cost.
Resistance Management. Good stewardship of herbicide resources is important to sustaining effectiveness of these critical and limited tools, even in rangelands where resistance issues are currently less widespread than in crop production. The best herbicide use strategy to prevent selection of herbicide resistant weed populations is to tank mix multiple modes of action in every application, and premixes can be an easy way to do so. To be effective for resistance management purposes, a tank mix must include multiple modes of action that are each effective on the target weed.
|
Active Ingredients |
Trade Name(s) |
|
2,4-D + aminopyralid |
Forefront HL, GrazonNext HL, PasturAll HL, Forefront HL, Gunslinger AMP |
|
2,4-D + clopyralid |
Commando, Cody, Curtail |
|
2,4-D + dicamba |
Brash, Brush-Rhap, Burnmaster, Latigo, Outlaw, RangeStar, Rifle D, Spitfire, Veteran 720, Weedmaster |
|
2,4-D + dicamba + fluroxypyr |
E2, Scorch |
|
2,4-D + picloram |
Graslan L, Grazon P+D, Gunslinger P+D, Trooper P+D, |
|
2,4-D + triclopyr |
Crossbow, Candor, Crossroad, Everett |
|
aminopyralid + clopyralid |
Sendero |
|
aminopyralid + metsulfuron |
Chaparral, Opensight |
|
aminopyralid + picloram + fluroxypyr |
MezaVue |
|
aminopyralid + triclopyr |
Capstone, Milestone VM Plus |
|
chlorsulfuron + metsulfuron |
Cimaron Plus |
|
clopyralid + MCPA |
Curtail M, Commando M |
|
clopyralid + triclopyr |
Prescott |
|
dicamba + halosulfuron |
Yukon |
|
dicamba + triasulfuron |
Rave |
|
fluroxypyr + picloram |
Triumph XTR, Surmount |
|
fluroxypyr + triclopyr |
Cleargraze, Pasturegard HL |
|
imazapyr + metsulfuron |
Lineage Clearstand |
|
indaziflam + rimsulfuron |
Esplanade Sure |