Grass Hay

Tim Prather
Revised: 
March 2016

2,4-D amine (several trade names)

Rate 0.7 to 2 lb ae/A

Time Depends on weeds to be controlled. Apply to grass when annual and biennial broadleaf weeds are small and actively growing, and established perennials are at bud stage, unless label indicates otherwise.

Remarks Controls many broadleaf weeds. Application rate depends on weed species and size. 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. Spray perennial weeds while they are still seedlings (coming from seed) or wait until bud stage of growth.

Caution Do not allow spray 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. Do not cut for hay within 30 days of application. Do not graze lactating dairy cattle in treated areas for 7 days after application. 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)

Rate 0.75 to 1.75 oz ae/A (3 to 7 fl oz/A Milestone)

Time Apply to actively growing weeds. Consult label for specifics.

Remarks A nonionic surfactant at 1 to 2 quarts/100 gal spray will enhance control under adverse environmental conditions. Controls several broadleaf weeds. Application rate depends on weed species and stage of growth. Apply at least 2 weeks before harvest to ensure weed control. There are no restrictions on grazing or hay harvest.

Caution Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Allow at least 3 days of grazing on an untreated pasture before transferring grazing animals from treated areas where sensitive broadleaf crops grow. Do not exceed 7 fl oz/A Milestone per year. Do not spread manure from animals that have grazed or consumed treated forage within the previous 3 days on land used for growing broadleaf crops. If Milestone is applied by someone besides the landowner, a copy of Dow AgroSciences Stewardship instructions must be provided: aminopyralidstewardshipinstructions.com. Not for use in hay for export.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

aminopyralid + 2,4-D (ForeFront HL)

Rate 0.06 to 0.11 lb ae aminopyralid + 0.5 to 0.87 lb ae 2,4-D/A (1.5 to 2.6 pints/A product)

Time Apply to actively growing weeds under conditions favorable for plant growth.

Remarks Rate depends on target broadleaf weed species. Use a higher rate when growing conditions are less than favorable, weeds are mature or weed foliage is tall and dense, or when residual control is important. Adding a high-quality nonionic surfactant, at 0.25 to 0.5 v/v, enhances control.

Caution Do not let spray drift onto desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not harvest for hay within 7 days. Allowing at least 14 days after application before harvest provides maximum herbicidal activity. Do not transfer grazing animals from treated areas to areas where sensitive broadleaf crops grow without first allowing 3 days of grazing on untreated pastures. Do not spread manure from animals that have grazed or consumed treated forage within the previous 3 days on land used for growing broadleaf crops. If Milestone is applied by someone besides the landowner, a copy of Dow AgroSciences Stewardship instructions must be provided (www.aminopyralidstewardshipinstructions.com). Not for use in hay for export.

Site of action Group 4: synthetic auxin

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

bromoxynil + pyrasulfotole (Huskie)

Rate 0.185 to 0.205 lb ai/A bromoxynil + 0.033 to 0.036 lb ai/A pyrasulfotole (13.5 to 15 oz/A Huskie)

Time Apply preemergence to established hay. See label for weed size recommendations and application timings, but control of most species is best at the 15 fl oz/A rate when weeds have from one to six leaves. Two applica­tions of Huskie can be made per year separated by at least 30 days.

Remarks For most consistent weed control under adverse grow­ing conditions, add AMS or an ammonium nitrogen source as directed by the spray additives section of the label, but do not use these additives if crop injury is a concern. Huskie may be tank mixed with a variety of other broadleaf and grass herbicides and other pesticides; see label for instructions.

Caution See label for crop rotation restrictions. Wheat, triticale, and oats may be planted 1 month after application; most other crops may be planted 9 months after application. Do not graze or cut grass for forage within 7 days of application, or cut grass for hay within 30 days of application. Do not exceed 30 oz/A of Huskie per year. Aerial and chemigation applications are prohibited.

Site of action (bromoxynil) Group 6: photosystem II inhibitor; (pyrasulfotole) Group 28: inhibits 4hydroxyphenylpy­ruvatedioxygenase (4-HPPD)

Chemical family (bromoxynil) nitrile; (pyrasulfotole) isoxazole

carfentrazone (Aim EC)

Rate 0.008 to 0.031 lb ai/A (0.5 to 2 fl oz Aim EC)

Time Apply to emerged and actively growing annual broadleaf weeds no more than 4 inches tall or across. May be applied before seeding and up to jointing stage of crop.

Remarks Add surfactant; see label for mixing and application directions. Apply in at least 10 gal/A of spray solution. See label for control of specific weeds and adjuvant recommendations. There are no harvest or grazing restrictions.

Caution Do not exceed 0.093 lb ai/A (5.9 fl oz/A Aim EC) or three applications per season.

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

Chemical family Triazolinone

clopyralid (Stinger, Transline)

Rate 0.125 to 0.5 lb ae/A (0.33 to 1.33 pints/A product)

Time Depends on weeds to be controlled. Apply to grass when annual and biennial broadleaf weeds are small and actively growing, and established perennials are at bud stage of growth unless label indicates otherwise.

Remarks Controls some broadleaf weeds. Application rate depends on weed species and size. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage and before flower stalks appear. Spray perennial weeds while they are still seedlings (coming from seed) or wait until bud stage of growth unless label indicates otherwise. There are no restrictions on haying or grazing after applying Stinger if used alone at labeled rates.

Caution Do not allow drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Do not use plant residues—including hay from treated areas and manure from animals that consumed forage from treated areas—for composting or mulching where susceptible plants may be grown the following season. Do not spread manure from animals that have grazed or consumed forage from treated areas on land for growing susceptible broadleaf crops. Do not exceed 4 pints/A per year.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

clopyralid + 2,4-D (Curtail)

Rate 0.21 to 0.42 lb ae/A clopyralid + 1.175 to 2.35 lb ae/A 2,4-D (2 to 4 quarts/A product)

Time Apply to grass 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 spray to drift to 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 cut for hay within 30 days of application. Do not graze lactating dairy cattle in treated areas for 14 days after application. Do not permit animals being finished for slaughter to graze freshly treated fields within 7 days of slaughter. Removal is not needed after 2 weeks from application. Do not use hay or straw from treated areas for composting or mulching. Do not spread manure from animals that have grazed or consumed treated forage within the previous 3 days on land used for growing broadleaf crops. Note label restrictions on overseeding or reseeding.

Site of action Group 4: synthetic auxin

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

dicamba (Banvel or Clarity)

Rate 0.25 to 2 lb ae/A (0.5 to 4 pints/A product)

Time Depends on weeds to be controlled. Apply to grass when annual and biennial broadleaf weeds are small and actively growing, and established perennials are at bud stage of growth unless label indicates otherwise.

Remarks Controls many broadleaf weeds. Application rate depends on weed species and size. 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. Spray perennial weeds while they are still seedlings (coming from seed) or wait until bud stage of growth. Maximum rate per season is 2 lb ai/A. There are no haying or grazing restrictions except for lactating dairy animals.

Caution Do not allow drift onto desirable vegetation. Do not apply to newly seeded areas until grass is well established. Desirable vegetation (including broadleaf plants) can be seriously injured or killed.

Restrictions Treated hay for lactating dairy animals: If up to 0.5 lb ae/A (1 pint) was used, delay harvest 37 days; if up to 1 lb ae/A (2 pints) was used, delay harvest 51 days; if up to 2 lb ae/A (4 pints) was used, delay harvest 70 days. Do not graze lactating dairy animals in treated areas for 7 to 40 days after treatment, depending on usage rate.

Site of action Group 4: synthetic auxin

Chemical family Benzoic acid

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

Rate 0.5 to 4 pints/A Weedmaster or Pasturemaster, or 0.33 to 2.5 pints/A Latigo

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

Remarks Controls broadleaf weeds. Application rate depends on weed species and size. 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. Unless label indicates otherwise, spray perennial weeds while they are still seedlings (coming from seed) or wait until bud stage of growth.

Caution Do not allow spray to drift onto 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 cut for hay for lactating dairy animals within 37 days of application. Do not graze lactating dairy cattle in treated areas for 7 days after application. Do not permit animals being finished for slaughter to graze treated fields within 30 days of slaughter. Note label restrictions on overseeding or reseeding.

Site of action Group 4: synthetic auxin

Chemical family (dicamba) Nitrile; (2,4-D) Phenoxy acetic acid

dicamba + diflufenzopyr (Overdrive)

Rate 0.0156 to 0.03125 lb ae/A dicamba + 0.00625 to 0.0125 lb ae/A diflufenzopyr (4 to 8 oz/A Overdrive)

Time Apply to annual and biennial broadleaf weeds when they are small and actively growing, and established perennials are at bud stage.

Remarks Controls broadleaf weeds. Application rate depends on weed species and size. The smaller the annual weeds, the easier they are to control.

Caution Do not allow spray to drift onto 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. A maximum of 8 ounces may be used per season.

Site of action Group 4: synthetic auxin

Chemical family (dicamba) nitrile; (diflufenzopyr) semicarbazone

flufenacet + metribuzin (Axiom DF)

Rate 0.27 to 0.31 lb ai/A flufenacet + 0.068 to 0.084 lb ai/A metribuzin (8 to 10 oz/A Axiom) in established timothy hay.

Time Apply before weeds emerge, or no later than the two-leaf stage of volunteer grasses.

Remarks Do not graze timothy in the fall and cut height cannot be shorter than 3.5 inches. Rain or irrigation after application is needed for sufficient weed control activity.

Caution Harvest at lower than 3.5 inches may cause injury to timothy. Grazing in fall after hay harvest may cause injury to timothy. It is best to harvest at 4 inches to allow energy stored in stems to be used to produce new stems next year.

Site of action (flufenacet) Group 15: inhibits very long chain fatty acid synthesis; (metribuzin) Group 5: photosystem II inhibitor

Chemical family (flufenacet) oxyacetamide; (metribuzin) triazinone

fluroxypyr (Starane Ultra)

Rate 0.11 to 0.14 lb ae/A (0.3 to 0.4 pints/A product)

Time Apply in spring when broadleaf weeds are actively growing and are less than 8 inches tall.

Remarks Only weeds emerged at the time of treatment will be controlled. May be applied to bluegrass, bromegrass, fescue, orchardgrass, ryegrass, timothy and sorghum, sorghum-sudan, sudan, and triticale. A second application may be made no less than 14 days after the first. There are no grazing restrictions.

Caution Do not let spray drift onto desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not harvest for hay or silage within 7 days of application. Meat animals must be withdrawn from treated forage at least 2 days before slaughter. Do not exceed 0.25 lb ae/A (0.7 pints/A) per growing season.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

glyphosate (several trade names)

Rate Consult label. Several formulations and concentrations are available.

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

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

Caution Kills forage plants on contact. Do not allow drift to 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 + dicamba (Yukon)

Rate 0.5 to 1 oz ai/A halosulfuron + 2.2 to 4.4 oz ai/A dicamba (4 – 8 oz product/A)

Time Postemergence broadcast application to established forage grasses/hay. Apply uniformly with ground equipment in a minimum of 10 gal of water per acre. Use a water volume that will provide uniform coverage of plants.

Remarks Do not apply more than 8 oz/A Yukon per year. For new pasture seeding, apply after the grasses are well established and have developed a secondary root system. It is recommended to make an application as soon as possible after removal of hay or before weeds exceed label height restriction.

Caution Wait for at least 48 hours after application before irrigation.

Site of Action Group 2, acetolactate synthase (ALS) inhibitor , Group 4 synthetic auxin

Chemical family Sulfonylurea, Benzoic acid

MCPA (Clean Crop MCP Amine 4)

Rate 1 to 1.5 lb ae/A (1 to 1.5 quarts/A product)

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 and grass hay.

Caution Do not graze dairy animals for 7 days after treatment. Do not harvest for hay less than 21 days after application. Do not graze meat animals in treated areas within 7 days of slaughter. Do not use this treatment if alfalfa is present and desirable. 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 0.0188 to 0.124 (0.5 to 3.3 oz/A Escort)

Time Apply to actively growing weeds and in established grasses.

Remarks Controls a wide range of broadleaf weeds. For best results, use a nonionic or silicone surfactant. No grazing restrictions for any livestock, including lactating animals, with application rates up to and including 2 oz ai/A (3.3 oz/A product). Note grazing restrictions with higher rates. Note label restrictions for use on timothy and fescue, which must be established 12 and 24 months respectively, and for use on ryegrass pastures. Note recropping intervals that are dependent on soil pH on the label.

Caution Do not allow drift to desirable vegetation. Injures or kills desirable forbs. Do not use if soil pH is above 7.9.

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

Chemical family Sulfonylurea

saflufenacil (Sharpen)

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

Time Apply only to established stands of perennial cool-season and warm-season forage grasses.

Remarks A methylated seed oil is required for postemergence control of broadleaf weeds. See label for more information on adjuvants and tank-mixes.

Caution Do not exceed 6 fl oz/A per year. Sharpen may cause leaf necrosis under certain conditions, but new growth is normal and vigor is not reduced. Disease, extremely cold weather, drought, extensive frost heaving, low or high pH, salinity, and other environmental pressures may weaken grass stands and make the crop more susceptible to herbicidal injury

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

Chemical family Pyrimidindione

triclopyr (Garlon 3A)

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

Time Apply when woody plants and broadleaf weeds 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. Do not harvest for hay within 14 days of application.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

triclopyr + 2,4-D (Crossbow)

Rate 1 to 1.5% solution for spot treatments or up to 1 gal/A product

Time Apply to grass when broadleaf weeds are actively growing.

Remarks Do not apply to forage that is to be cut and sold for commercial purposes. Controls many broadleaf weeds and is very effective on a number of woody species. Rate depends on weeds to be controlled. The smaller the annual weeds, the easier they are to control. Spray biennial weeds in the seedling to rosette stage and before flower stalks appear.

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 harvest for hay for 14 days after application. Note haying and grazing restrictions, particularly for lactating dairy cattle on the label. Note label restrictions on overseeding or reseeding.

Site of action Group 4: synthetic auxin

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

triclopyr + fluroxypyr (PastureGard)

Rate 0.56 to 1.5 lb ae triclopyr + 0.19 to 0.5 lb ae fluroxypyr/A (3 to 8 pints/A product)

Time Apply when weeds are small and actively growing, before the bud stage of growth.

Remarks Adjust rate for target vegetation. Controls emerged herbaceous and woody broadleaf plants. To control biennial thistles or other biennial species, apply before flower stalks appear. An agricultural surfactant may be added to improve foliar wetting.

Caution Do not let spray drift onto 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 or consuming treated hay at least 3 days before slaughter during the season of application. Do not harvest for hay within 14 days of application. Do not exceed 4 quarts/A of PastureGard per annual growing season.

Site of action Group 4: synthetic auxin

Chemical family Pyridine