Conservation Reserve Program
Mary Corp
Revised November 13, 2008

The Conservation Reserve Program (CRP) is designed to control erosion on cropland by planting permanent crops. A combination of desirable plants, trees, grasses, legumes, and/or shrubs must be planted and maintained  for the duration of the contract. CRP land may not be harvested or grazed by domestic animals. In addition to grasses, most new acreage in this program may include alfalfa and/or clovers. A portion of the qualifying acreage may include broadleaf plants such as flax, yarrow, and sagebrush. The combination of desirable grasses and broadleaf plants makes weed control difficult. Read herbicide labels carefully. Use the following text as a starting point. Be prepared for some level of damage to desirable plants, especially to legume species.
Certain noxious weeds must, by law, be controlled; the list of weeds is made in the counties and varies depending on locality. Also, weed control in the first year is crucial for good stand establishment.
Caution  Herbicides applied to CRP land usually will be extremely harmful to broadleaf crops. When CRP land adjoining cropland is sprayed by air or ground, take care to avoid drift onto cropland.
CONSERVATION RESERVE PROGRAM 
•  aminopyralid (Milestone)
Rate  4 to 7 fl oz/A, 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 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.
Caution  Do not use if loss of legumes species or other broadleaf species cannot be tolerated.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  aminopyralid + 2,4-D (ForeFront)
Rate  1.5 to 2 pints/A, 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.
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
•  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  1 to 1.5 pint/A of 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) none generally accepted
•  glyphosate
Rate  0.28 to 0.38 lb ae/A to control small (2 to 4 inches) 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  None generally accepted
•  paraquat (Gramoxone, Inteon, 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  Best results when used when weeds are small. Always use an 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
•  2,4-DB
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.
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
•  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 yr 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 or Rifle) 
Rate  Refer to label for rate selection based on targeted weed or brush species. Rates of about 4 pints/A for spot treatments only.
Remarks  Do not spray when grass is 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
•  triclopyr (Remedy)
Rate  1 to 2 pints/A or up to 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 1 to 2 quarts/A of 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  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
•  metsulfuron (Cimarron)
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 of 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) also 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
•  chlorsulfuron (Telar)
Rate  0.25 to 1.33 oz/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  Telar severely injures broadleaves such as clover and alfalfa.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  picloram (Tordon)
Rate  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
•  clopyralid (Transline, Stinger, or Clopyr Ag)
Rate  0.33 to 1.33 pints/A. 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 nonleguminous 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  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  1.33 to 2.66 pints/A, not to exceed 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
•  bromoxynil (Buctril)
Rate  1 to 2 pints/A Buctril
Time  Apply spring or fall after grasses have reached the two- to three-leaf stage. 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  1 to 2 pints/A Bronate or WildCard XTRA 
Time  Apply in spring or fall after grasses have reached the three-leaf stage.
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
•  fluroxypyr + 2,4-D (Starane + Salvo)
Rate  1.33 to 2.66 pints/A
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
•  pendimethalin (Prowl or Stealth)
Rate  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 legume cover crops established after application. Do not use on peat or muck soils. The legume cover crop may be reduced somewhat.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
CONSERVATION RESERVE PROGRAM—Winter Annual Grasses
•  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
•  imazapic (Plateau)
Rate  2 to 6 oz/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 (Pursuit W)
Rate  4 fl oz/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
•  triasulfuron (Amber)
Rate  0.28 to 0.56 oz/A
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
•  pronamide (Kerb or Break-UP)
Rate  0.2 lb ai/A (0.4 lb/A Kerb or Break-UP)
Time  Between mid-October and mid-December.
Remarks  For CRP fields that have an acceptable stand of grass that has been established at least 1 yr. 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  Benzamidebreakhere