Annual and Perennial Ryegrass

Note Also see GRASS SEED-New and Established for herbicides that may be used on many species of grass grown for seed.

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 from preemergence to established perennial and annual ryegrass. 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 grass 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. Huskie will control mannagrass in annual ryegrass grown for seed.

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

dimethenamid-P (Outlook)

Perennial ryegrass only

Rate 0.66 to 0.98 lb ai/A (14 to 21 fl oz/A Outlook)

Time Apply in fall before targeted weeds emerge or in midwinter in a sequential-use program with other herbicides that control emerged weeds.

Remarks Grass seed crops must be established at least 1 year, or have had at least one seed crop harvested before Outlook is applied. Apply higher rates where denser weed infestations are expected. Excessive straw on the field after harvest may reduce weed control. Sufficient rain or irrigation after application is needed for optimum weed control. May be applied by ground or by air (see label).

Caution Applying to perennial ryegrass under stress may injure crop. Do not apply Outlook in tank-mixtures with other herbicides unless risk of crop injury is acceptable. Subsequent applications may injure crop. Do not allow livestock to graze treated fields for 60 days after application. Treated straw, seed, or seed screenings may be fed to livestock following harvest.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide

diuron (several trade names)

Perennial ryegrass; Annual ryegrass for the creation of rows; Oregon and Washington only

Rate 0.8 to 2.4 lb ai/A (1 to 3 lb/A of an 80DF formulation)

Time At the onset of fall rains and before weeds are beyond the 2- to 4-leaf stage.

Remarks Do not apply to perennial ryegrass less than 1 year old. There are several suppliers of diuron; check labels for crop and geographical restrictions. Application rate on perennial ryegrass depends on geographical location. See labels for instructions on the use of directed sprays of diuron for row creation while planting annual ryegrass or after annual ryegrass has emerged prior to the 2 leaf stage.

Site of action Group 7: photosystem II inhibitor

Chemical family Substituted urea

ethofumesate (several trade names)

West of Cascades in Oregon and Washington only

Rate 0.75 to 1.9 lb ai/A (1.5 to 3.75 pints/A product)

Time Apply after planting ryegrass but no later than four-leaf stage of weeds. Apply preemergence or early postemergence of annual ryegrass, or early postemergence (two leaves) of perennial ryegrass. Apply before two-leaf stage to control rattail fescue and wild oat. Apply preemergence to annual bluegrass for best control.

Remarks To control ethofumesate-susceptible biotypes of annual bluegrass, mannagrass (Glyceria spp.), rattail fescue, volunteer cereals, wild oat, and other winter annuals. Use higher application rates if weeds are emerged or rattail fescue and volunteer wheat are present. Carbon-banded fields should have 2 inches or more of rain to dissipate the carbon band before applying ethofumesate. Ethofumesate is most effective when applied to a firm seedbed that is free from crop residue. Soil surface should be moist at the time of application. Rain or sprinkler irrigation should follow soon after application to increase herbicide effectiveness.

Caution Do not graze treated fields. Do not rotate with any crops other than sugar beets or ryegrass for 12 months after application.

Site of action Group 16: unknown

Chemical family Benzofuran

flufenacet + metribuzin (Axiom DF)

Rate 0.3 to 0.4 lb ai/A flufenacet + 0.076 to 0.111 lb ai/A metribuzin (9 to 13 oz/A Axiom) in established perennial ryegrass; 0.27 to 0.34 lb ai/A flufenacet + 0.068 to 0.085 lb ai/A metribuzin (8 to 10 oz/A Axiom applied in a band) in annual ryegrass for row creation with a shielded sprayer.

Time Apply before weeds emerge, or no later than the two-leaf stage of volunteer grasses in established perennial ryegrass fields. Applications after mid-November may result in crop injury and/or poor weed control.

Remarks For established perennial ryegrass seed fields only (at least 1 year old, or after first seed harvest) or for row creation in annual ryegrass grown for seed. Weed control may be reduced if heavy straw loads remain on fields after harvest. Rain or irrigation after application is needed for sufficient weed control activity.

Caution Do not apply in tank-mixtures with postemergence herbicides. Applying oxyfluorfen or photosynthesis-inhibiting postemergence herbicides within 4 weeks of Axiom may injure perennial ryegrass. Application to perennial ryegrass after the second harvest may injure crop. Rates of 9 to 11 oz/A minimize injury in perennial ryegrass seed fields, especially in areas of the field with light soil textures. Preharvest interval is 120 days. Do not apply more than once per year. Do not allow animals to graze treated fields for a minimum of 30 days following application.

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

mesotrione (Callisto)

Rate 0.094 to 0.188 lb ai/A (3 to 6 oz/A Callisto)

Time Apply preemergence to bare soil or as an early postemergence application to emerged annual ryegrass to control grasses such as ethofumesate-resistant biotypes of mannagrass. Apply preemergence to bare soil or early postemergence to perennial ryegrass grown for seed.

Remarks The 3-oz/A rate will control mannagrass in annual ryegrass grown for seed. Use higher application rates for suppression of other grass and broadleaf weed species and for extended soil residual control. Adding crop oil concentrate or nonionic surfactant at 1% v/v will optimize activity of postemergence applications. In addition, urea ammonium nitrate at 2.5% v/v or ammonium sulfate at 8.5 lb/100 gal of spray solution may be added, but the risk of grass seed crop injury increases at rates above 3 oz/A of Callisto.

Caution Preharvest interval for seed and straw harvest after applications of Callisto is 60 days for perennial and annual ryegrass grown for seed. Do not graze or feed forage from treated fields within 14 days following harvest of seed or straw and at least 74 days after application. Do not exceed two applications or 9 oz/A of Callisto per year. Do not tank mix Callisto with other pesticides with EC formulations or crop injury will result from postemergence applications.

Site of action Group 28: inhibits 4hydroxyphenylpyruvatedioxygenase (4-HPPD)

Chemical family Triketone

metribuzin (several trade names)

Perennial ryegrass only; Washington, western Oregon, and Crook, Deschutes, Jefferson, and Wasco counties of Oregon only

Rate 0.25 to 0.375 lb ai/A in Washington; 0.25 to 0.56 lb ai/A in Oregon

Time When volunteer grasses are in the one- to two-leaf stage after fall rain or irrigation but before active spring growth.

Remarks Established grass crops only. Control of volunteer crop and grass weeds may be improved by adding a surfactant or crop oil blend at rates recommended on the wetting agent label.

Caution Allow at least 28 days after application before grazing. Allow at least 120 days between application and seed harvest. See additional cautions on individual labels.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazinone

oxyfluorfen (Goal 2XL or Galigan 2E)

Perennial ryegrass only; Oregon only

Rate 0.03 to 0.046 lb ai/A (2 to 3 oz/A Goal 2XL or Galigan 2E)

Time Apply on new plantings that have at least one tiller or more per plant. Applications to plants with less than one tiller may result in severe crop injury or stand loss. For best results, apply at early postemergence to the target annual broadleaf weeds.

Remarks Oxyfluorfen may be applied alone or in a tank-mix with up to 3 pints/A of ethofumesate. Crop may be discolored temporarily and, when tank mixed with ethofumesate, crop injury may increase. Goal and Galigan SLN labels vary by state.

Caution Application of oxyfluorfen in a tank-mix with ethofumesate is at the sole discretion of the grower and at the grower's own risk. Do not apply to a crop that is under stress, because additional crop injury may occur. Review the specific oxyfluorfen SLN you are using for updated preharvest and grazing restrictions.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Diphenylether

oxyfluorfen (Goal 2XL or Galigan 2E)

Perennial ryegrass only; Oregon and Washington only

Rate 0.125 to 0.375 lb ai/A (8 to 24 oz/A Goal 2XL or Galigan 2E)

Time Apply during fall and midwinter, before or soon after weeds emerge. Apply first before weed (grass) seedlings to be controlled exceed the two-leaf stage, preferably before December 15. Make final applications before mid-January.

Remarks Apply to established fields that have at least six tillers per plant. Fields may be treated more than once but with no more than a total of 24 oz/A during a crop season. Goal and Galigan SLN labels vary by state.

Caution Oxyfluorfen applications might substantially discolor crop foliage. Leaf chlorosis and reduced vegetative growth are typical plant responses to oxyfluorfen treatments. If using a tank-mix with diuron, do not exceed 1.2 lb ai/A diuron in a season. Review the specific oxyfluorfen SLN you are using for updated preharvest and grazing restrictions.

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

Chemical family Diphenylether

pendimethalin (Prowl H2O)

Perennial ryegrass only

Rate 2 to 3 lb ai/A (4.2 to 6.3 pints/A Prowl H2O)

Time Apply at the beginning of significant fall rains, and before weeds germinate. Treatments are most effective with adequate rain or overhead irrigation within 7 days after application.

Remarks For established grass fields only (six or more tillers). Prowl will not control established weeds. See label for specifics on tank-mixes with other herbicides. Removing excessive straw and crop residues may increase effectiveness. Fall applications made to perennial grasses which exceed 6 inches in height may result in reduced weed control due to reduced spray coverage to bare soil.

Caution May temporarily injure grass stands. Tank-mixtures, and applications under extreme weather conditions and to weak stands, may increase crop injury. Do not harvest forage from treated fields within 45 days of application or harvest hay from treated fields within 60 days of application. The PHI for seed production is 90 days and grass seed screenings may not be used in livestock feed. Grass seed straw from treated fields may be fed to livestock and treated fields may be grazed after harvest. Refer to main labels for crop rotation restrictions.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

S-metolachlor (several trade names)

Perennial ryegrass only

Rate 0.95 lb ai/A

Time Apply to established stands just before, during, or immediately after the first fall rains or an irrigation. Treat target weeds before they emerge.

Remarks Apply only to stands harvested for seed at least once or planted at least 1 year before treatment. Rain or irrigation is required after application and before weeds emerge for best weed control.

Caution Apply only once during a crop season. Applications when crop is under stress may cause injury. Do not apply after November 15. Tank-mixtures with postemergence herbicides may injure crop. See specific labels for grazing and feeding restrictions based on geography.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide

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