Conservation Reserve Program

Andy Hulting and Ed Peachey
Revised December 2013

The Conservation Reserve Program (CRP) is designed to control erosion, improve water quality and enhance wildlife habitat on environmentally sensitive land by planting permanent crops. A combination of desirable plants including trees, grasses, legumes, and shrubs must be planted and maintained for the duration of the contract which usually runs for 10 to 15 years. CRP land may not be harvested or grazed by domestic animals except under emergency circumstances following natural disasters, or certain other managed conditions. In addition to grasses, most new acreage in this program may include plantings of alfalfa and/or clovers. A portion of the qualifying acreage may also include other broadleaf plants such as flax, yarrow, and sagebrush. This combination of desirable grasses and broadleaf plants makes weed management difficult. Read herbicide labels carefully. Use the following text as a starting point to select the proper herbicides to apply in CRP. Be prepared for some level of damage to desirable plants following herbicide applications, especially to legume species.

By law, certain noxious weeds must be controlled. The list of weeds is created at the county level; it varies depending on locality. Also, weed control in the first year is crucial for good stand establishment of the desirable CRP species.

Caution Herbicides applied to CRP land may be extremely harmful to nearby crops. When CRP land adjoining cropland is sprayed by air or ground, take exceptional care to avoid drift onto cropland.

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 CRP 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.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

2,4-DB (several products)

Rate 1 to 3 quarts/A

Time Apply postemergence to grasses with at least six leaves and to forage legumes (seedling or established alfalfa, seedling birdsfoot trefoil, seedling alsike clover, seedling ladino clover, or seedling red clover) that are emerged and actively growing.

Remarks Weeds must be small to achieve adequate control.

Caution Do not use on sweet clover, peas, or other legumes not mentioned above. Do not spray when temperatures exceed 90°F.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

aminopyralid (Milestone)

Rate 0.0625 to 0.109 lb ae/gal (4 to 7 fl oz/A Milestone), depending on specific weed species

Time Annual and biennial thistles and knapweeds: optimum time is from rosette to bolting stage, or in the fall on seedlings. Perennial thistles and knapweeds, leafy spurge: optimum time is when fully emerged in spring up to bud growth, and in the fall before a killing frost.

Remarks Uniform coverage is needed for best results. Residual activity will help control later-emerging weeds. Consult label for grazing and haying restrictions.

Caution Do not use if loss of legume species or other broadleaf species cannot be tolerated.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

aminopyralid + 2,4-D (ForeFront)

Rate 0.077 to 0.103 lb ae/A aminopyralid + 0.624 to 0.833 lb ae/A 2,4-D (1.5 to 2 pints/A ForeFront), depending on specific weed species, or up to 5 pints/A as a spot treatment.

Time Use lower rates on small, actively growing broadleaf weeds; increase rate as season progresses and plants mature.

Remarks Consult label for grazing and haying restrictions.

Caution Do not use if loss of legumes species or other broadleaf species cannot be tolerated.

Site of action (both) Group 4: synthetic auxin

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

aminopyralid + metsulfuron (Chaparral)

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 Chaparral)

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. Consult label for grazing and haying restrictions.

Caution Do not let spray drift onto desirable vegetation. Many forbs (desirable broadleaf plants in CRP) will be seriously injured or killed.

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

Chemical family (aminopyralid) Pyridine; (metsulfuron) Sulfonylurea

aminopyralid + triclopyr (Capstone)

Rate 0.05 to 0.075 lb ae/A aminopyralid + 0.5 to 0.75 lb ae/A triclopyr (4.0 to 6.0 pints/A Capstone)

Time Apply to actively growing broadleaf weeds and woody plants. Consult label for application rates for specific weed and tree species.

Remarks A nonionic surfactant applied at 0.25% to 0.5% v/v of spray solution enhances control under adverse environmental conditions. Application rate depends on weed species and stage of growth. Consult label for grazing and haying restrictions.

Caution Do not let spray drift onto desirable vegetation. Many forbs (desirable broadleaf plants in CRP) will be seriously injured or killed.

Site of action (both) Group 4: synthetic auxin

Chemical family (both) Pyridine

atrazine (several products)

Rate 1 to 2 lbs ai/A (1 to 2 quarts/A) atrazine (4 lb/gal)

Time For use in establishment or renovation of CRP grasslands. Preemergence applications of atrazine generally result in the greatest levels of weed suppression.

Remarks See atrazine labels for listing of specific grass species that are tolerant to atrazine applications. Atrazine will control a wide variety of grass and broadleaf weed species common in CRP.

Caution Atrazine labels for use in CRP vary by state and by specific products. In Oregon, do not apply more than 2.0 lb ai/A of atrazine for any application, and make no more than one application per year.

Site of action Group 5: photosystem II inhibitor

Chemical family triazine

bromoxynil (several products)

Rate 0.25 to 0.50 lb ae/A

Time Apply spring or fall after grasses have reached the two- to three-leaf stage to control broadleaf weeds. If alfalfa is planted, apply after the four-trifoliolate leaf stage.

Remarks Can be applied safely to alfalfa. Most effective on small weeds, defined as the four-leaf stage, 2 inches high, or 1 inch in diameter, whichever comes first.

Caution Do not apply to alfalfa when air temperature is expected to exceed 80°F.

Site of action Group 6: photosystem II inhibitor

Chemical family Nitrile

bromoxynil + MCPA (Bronate or WildCard XTRA)

Rate 0.25 to 0.50 lb ai/A each (1 to 2 pints/A Bronate or WildCard XTRA)

Time Apply in spring or fall after grasses have reached the three-leaf stage to control broadleaf weeds.

Caution Do not apply to grasses seeded with alfalfa; legumes may be severely injured.

Site of action (bromoxynil) Group 6: photosystem II inhibitor; (MCPA) Group 4: synthetic auxin

Chemical family (bromoxynil) nitrile; (MCPA) phenoxy acetic acid

bromoxynil + pyrasulfotole (Huskie)

Rate 0.228 to 0.254 lb ai/A (13.5 to 15 oz/A Huskie)

Time 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. Huskie may be tank mixed with a variety of other broadleaf herbicides labeled for use in CRP; see label for instructions.

Caution 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 Treat when weeds are small.

Remarks Apply with ground equipment using at least 10 gal/A of finished spray. See label for control of specific weeds and adjuvant recommendations.

Caution Allow at least 7 days between applications; do not exceed 5.9 fl oz/A or three treatments per season.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Triazinone

carfentrazone + glyphosate (Rage)

Rate 0.005 to 0.0075 lb ai/A carfentrazone + 0.625 to 0.938 lb ai/A glyphosate (1 to 1.5 pints/A Rage) for annual weeds less than 6 inches tall. Apply at least 2.5 pints/A Rage for annual weeds greater than 6 inches tall. See label for additional instructions on annual and perennial weeds.

Time Apply to actively growing annual and perennial weeds. Do not disturb foliage for at least 7 days following application.

Remarks A nonionic surfactant (NIS), methylated seed oil (MSO), or crop oil concentrate (COC) is required. Ammonium sulfate (AMS) at 2 to 4 lb/A may be used in addition to the nonionic surfactant, methylated seed oil, or crop oil concentrate. Do not reduce product use rate when AMS is used. See label for use of adjuvants.

Caution Do not exceed 272 fl oz/A Rage per season. Rage will kill any desirable seedlings it contacts.

Site of action Group 14: protoporphyrinogen oxidase inhibitor, Group 9: inhibits EPSP synthase

Chemical family (carfentrazone) triazinone; (glyphosate) glycine

chlorsulfuron (several products)

Rate 0.012 to 0.062 lb ai/A

Time Preemergence or postemergence in early stages of weed growth.

Remarks Label lists specific rates by weed species. Treat Canada thistle prebloom to bloom and/or at fall rosette.

Caution Chlorsulfuron severely injures broadleaves such as clover and alfalfa.

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

Chemical family Sulfonylurea

clopyralid (Transline, Stinger, or Clopyr Ag)

Rate 0.124 to 0.49 lb ae/A (0.33 to 1.33 pints/A product). Higher rates are for deep-rooted perennial weeds and less-than-ideal conditions.

Time Apply when weeds are young and actively growing.

Remarks Conifers and non-leguminous broadleaf trees are generally tolerant. Alfalfa is moderately tolerant. Sweet clover is tolerant.

Caution Ground application only.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

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). High rates are for deep-rooted perennial weeds.

Time Apply to established grasses when weeds are actively growing.

Caution Do not use if broadleaf plants are a desired cover. Read label for plant-back restrictions if rotating ground out of CRP. Do not apply by air during an air temperature inversion.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

clopyralid + fluroxypyr (WideMatch or Colt AS)

Rate 0.125 to 0.25 lb ae/A each (1.33 to 2.66 pints/A product), not to exceed 0.49 lb ae/A (5.33 pints/A) per season

Time Apply broadcast postemergence, when weeds are actively growing, but before 8 inches tall. To control perennial weed such as Canada thistle, apply when basal leaves are fully emerged up to bud stage.

Caution Do not use if broadleaf plants are a desired cover. Read label for plant-back restrictions if rotating ground out of CRP. Do not apply by air during an air temperature inversion.

Site of action (both) Group 4: synthetic auxin

Chemical family (both) pyridine

dicamba (Banvel or Clarity) + 2,4-D

Rate 0.12 to 2 lb ae/A dicamba + 0.25 to 1 lb ae/A 2,4-D

Time After grasses have three leaves in the establishment year, or in fall or spring on grasses more than 1 year old.

Remarks Use up to 0.25 lb ae/A dicamba and up to 0.5 lb ae/A 2,4-D in the establishment year. Do not spray stressed grasses.

Caution Legumes are sensitive to dicamba and 2,4-D

Site of action (both) Group 4: synthetic auxin

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

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

Rate Refer to label for rate selection based on targeted weed or brush species. Application rates of 4 pints/A for spot treatments only.

Remarks Do not spray when grasses are stressed.

Caution Legumes are sensitive to dicamba and 2,4-D.

Site of action (both) Group 4: synthetic auxin

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

dicamba + diflufenzopyr (Distinct or Overdrive)

Rate 0.125 to 0.25 lb ae/A dicamba + 0.05 to 0.10 lb ae/A diflufenzopyr ( to 8 oz/A Distinct or Overdrive)

Time Apply to CRP 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.

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

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

fluroxypyr (several products)

Rate 0.14 to 0.245 lb ai/A fluroxypyr

Time For best performance, apply to emerged and actively growing broadleaf weeds less than 4 to 8 inches in height. Only weeds that have emerged at time of application will be controlled.

Remarks Do not use on land with desirable legumes, clovers, or other sensitive broadleaf plants.

Caution Grazing or haying CRP treated with fluroxypyr is prohibited.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

fluroxypyr + 2,4-D (Starane + Salvo)

Rate 0.125 to 0.25 lb ae/A fluroxypyr + 0.49 to 1.0 lb ae/A 2,4-D (1.33 to 2.66 pints/A Starane + Salvo)

Time Weeds must be small, actively growing, and less than 8 inches tall.

Caution Do not use on land with desirable legumes, clovers, or other sensitive broadleaf plants.

Site of action (both) Group 4: synthetic auxin

Chemical family (fluroxypyr) pyridine: (2,4-D) phenoxy acetic acid

glyphosate (several products)

Rate 0.28 to 0.38 lb ae/A to control small (2 to 4 inch) grasses and certain broadleaf weeds. For perennial weeds, use 0.75 to 3.75 lb ae/A. Consult labels for rates for specific weeds.

Time Apply to actively growing weeds any time before planting, or before desirable grasses or legumes emerge. For selective broadcast applications, apply in early spring before desirable grasses break dormancy. Late fall applications can be made after desirable grasses have gone dormant.

Remarks Add 2 quarts of a nonionic surfactant, 80% ai or more, to each 100 gal of spray solution. Ammonium sulfate added to spray solution at 17 lb/100 gal may increase effectiveness on environmentally stressed plants. See label for additive rates for nonionic surfactants and ammonium sulfate.

Caution Glyphosate will kill any crop seedlings it contacts.

Site of action Group 9: inhibits EPSP synthase

Chemical family Glycine

MCPA (several products)

Rate 0.46 to 1.39 lb ae/A (1 to 3 pints/A MCPA-amine)

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 CRP.

Caution 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.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

metsulfuron (several products)

Rate 0.1 to 1 oz/A

Time Apply after weeds emerge, to grasses in the three- to four-leaf stage. Use higher rates on established grasses only.

Remarks Metsulfuron is labeled for use on many native and improved perennial grasses used in the CRP. See label for grass species. It controls a wide range of broadleaf weeds and inhibits Canada thistle growth. It will not control nightshades. For best results, weeds should be actively growing; add a surfactant of at least 80% ai at 1 to 2 quarts/100 gal. Cimarron Max (metsulfuron + dicamba + 2,4-D) and Cimarron Plus and Cimarron X-tra (metsulfuron + chlorsulfuron) are labeled for CRP.

Caution Do not use on soils with a pH greater than 8. Metsulfuron can persist in soil. Carefully follow label instructions on crop rotations when land is taken out of CRP. This material is not recommended for plantings that include a legume.

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

Chemical family Sulfonylurea

paraquat (Gramoxone Inteon, BonFire, or Firestorm)

Rate 0.25 to 1 lb ai/A (2 to 4 pints/A)

Time Apply any time before or after planting until desirable plants emerge.

Remarks For best results, use when weeds are small. Always use a nonionic surfactant, crop oil concentrate, or methylated seed oil with the application.

Caution A restricted-use herbicide.

Site of action Group 22: photosystem I electron diversion

Chemical family Bipyridilium

pendimethalin (Prowl H2O, Framework, or Stealth)

Rate 0.41 to 1.03 lbs ai/A (1 to 2.5 pints/A Prowl)

Time Apply preplant incorporated or preemergence before annual grasses and broadleaf weeds germinate.

Remarks Rate depends on soil type and organic matter content. If cover crop is lost because of bad weather, any crop registered for pendimethalin use and application method can be replanted the same year. If replanting, do not rework soil deeper than the pendimethalin-treated zone.

Caution Do not feed or graze CRP legume cover crops established after application. Do not use on peat or muck soils. The legume cover crop may be reduced somewhere.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

pendimethalin + dimethenamid (Freehand 1.75G)

Rate 1.0 to 2.0 lb ai/A pendimethalin + 0.75 to 1.5 lb ai/A dimethenamid (100 to 200 lb/A Freehand 1.75G)

Time Apply preemergence, before annual grasses and broadleaf weeds germinate.

Remarks For weed management during hardwood or conifer tree establishment or regeneration in CRP. Freehand may be applied at tree planting, or to established trees.

Caution Do not allow Freehand to come into direct contact with seedling tree roots. Do not apply to newly planted tree seedlings until soil is thoroughly packed or settled around the tree roots.

Site of action Group 3: microtubule assembly inhibitor; Group 15: inhibits very long chain fatty acid synthesis

Chemical family (pendimethalin) Dinitroaniline; (dimethenamid) Chloroacetamide

picloram (Tordon)

Rate 0.06 to 0.5 lb ae/A (0.25 to 2 pints/A Tordon)

Time Apply to established grasses when weeds are growing well.

Remarks To control many annual and perennial broadleaf weeds.

Caution A restricted-use herbicide. Legumes are highly sensitive to Tordon. Carefully follow label instructions on crop rotations when land is taken out of CRP.

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 CRP. Edict may be tank mixed with 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.

Site of action Group 14: protoporphyrinogen oxidase 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 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.

Site of action Group 4: synthetic auxin

Chemical family Quinoline carboxylic acid

sulfometuron-methyl (SFM 75)

Rate 0.35 to 0.375 lb ai/A (0.75 to 8 oz/A SFM 75)

Time For preemergence and postemergence control of many grass and broadleaf weeds in CRP.

Remarks Apply when weeds are actively germinating and emerging. Application rates are dictated by weed species and the amount of annual precipitation, with higher applications needed in wetter regions.

Caution Review label for list of tolerant grasses and grass or crop replant intervals following treatment with SFM 75.

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

Chemical family Sulfonylurea

triclopyr (Remedy)

Rate 0.5 to 1 lb ae/A (1 to 2 pints/A Remedy) or up to 1.5 lb ae/A (1.5 quarts/A) for deep-rooted perennial broadleaf and susceptible woody species

Time Apply when woody plants and weeds are actively growing. Adequate soil moisture before and after treatment is important.

Remarks Triclopyr premixed with clopyralid is available as Redeem R&P.

Caution Legumes are sensitive to Remedy.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

triclopyr + 2,4-D (Crossbow)

Rate 0.5 to 1 lb ae/A 2,4-D + 0.25 to 0.5 lb ae/A triclopyr (1 to 2 quarts/A Crossbow) to control annual broadleaf weeds or seedling perennial broadleaf weeds. Use up to 1.5 gal/A Crossbow for established perennials.

Time Apply only when perennial grasses are established and when weeds are growing well. Conditions that stress the grasses will increase potential for injury to grasses.

Caution Legumes are sensitive to Crossbow.

Site of action (both) Group 4: synthetic auxin

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

triasulfuron + dicamba (Rave)

Rate 0.011 to 0.028 lb ai/A triasulfuron + 0.063 to 0.156 lb ai/A dicamba (2 to 5 oz/A Rave)

Time Apply to small, actively growing weeds.

Remarks Label lists established grasses to which Rave can be applied.

Caution Do not apply Rave until at least 60 days after desirable grasses emerge.

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

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

CONSERVATION RESERVE PROGRAM—Winter Annual Grasses

imazapic (several products)

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

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

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

Caution Always use adjuvant; see label for details.

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

Chemical family Imidazolinone

imazethapyr (several products)

Rate 0.0625 lb ae/A

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

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

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

Chemical family Imidazolinone

pronamide (Kerb )

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

Time Between mid-October and mid-December.

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

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

Site of action Group 3: microtubule assembly inhibitor

Chemical family Benzamide

propoxycarbazone-sodium (Canter R + P)

Rate 0.039 to 0.053 lb ai/A (0.9 to 1.2 oz/A Canter R + P)

Time Fall or spring: apply specified dosage per acre as a postemergence broadcast spray to control a number of weedy winter annual grass species and some broadleaf weeds.

Remarks Use with nonionic surfactant (0.25% to 0.5% v/v). Two applications may be made per year, but do not exceed 1.2 oz/A Canter R + P/A per year. Fall applications may not control spring-germinating broadleaf weeds.

Caution See label for broadleaf herbicide tank-mix options with Canter R + P and additional information on tolerant desirable CRP grass species.

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

Chemical family Sulfonylaminocarbonyltriazolinone

sulfosulfuron (Outrider)

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

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

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

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

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

Chemical family Sulfonylurea

triasulfuron (Amber)

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

Time Postemergence to actively growing broadleaf weeds.

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

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

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

Chemical family Sulfonylurea