New and Established Crops

Broadleaf Weed Control

2,4-D amine, 2,4-D ester (several trade names)

Rate 0.36 to 0.75 lb ae/A. Follow individual labels.

Time Eastern Oregon: apply after new grass has established five leaves in non-irrigated grass or two leaves in irrigated grass. Western Oregon: apply 2,4-D at 0.5 lb ae/A to fall-seeded stands after the two-leaf stage of grass growth. Established stands: apply spring or fall before boot stage. Idaho and Washington seedling grasses: apply 0.36 to 0.47 lb ae/A of most esters or amines after the five-leaf stage.

Remarks For use on newly established grass seed and established stands.

Caution See individual labels for grazing restrictions. Do not allow drift. Do not use an oil carrier. If used with nitrogen fertilizer solutions, foliage may be damaged temporarily. Bentgrass seedlings should be well established before application. Grass seedling root development may be inhibited when 2,4-D is applied to early growth stages, so frequent irrigation when possible is important to help grasses establish.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

carfentrazone (Aim EC)

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

Time Apply to emerged and actively growing weeds when weeds are small. May be applied before seeding and up to jointing stage of crop.

Remarks See label for specific tank-mixes and adjuvants to control problem weed species. Apply in at least 10 gal/A of spray solution. Good spray coverage is essential for control.

Caution Do not exceed 0.093 lb ai/A of Aim EC per growing season.

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

Chemical family Triazinone

clopyralid (Stinger)

Rate 0.094 to 0.25 lb ae/A (0.25 to 0.66 pint/A Stinger)

Time Apply in spring before boot stage and/or as a postharvest fall treatment. To control late-emerging Canada thistle, treat preharvest after grass seed is fully developed; apply to Canada thistle after most basal leaves emerge but before bud stage.

Remarks Re-treat as necessary, but do not exceed 0.66 pint/A Stinger per calendar year.

Caution Do not use on bentgrass unless injury can be tolerated. See label for rotation guidelines if land is taken out of grass seed production. Do not apply by air during an air temperature inversion. Some grass-seed straw export markets will not accept straw from grasses treated with clopyralid containing products.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

clopyralid + 2,4-D (Curtail)

Rate 0.095 to 0.19 lb ae/A clopyralid + 0.5 to 1 lb ae/A 2,4-D (2 to 4 pints/A Curtail)

Time Apply in spring before boot stage and/or as a postharvest fall treatment. To control late-emerging Canada thistle, treat preharvest after grass seed is fully developed; apply to Canada thistle after most basal leaves emerge but before bud stage.

Remarks Curtail contains 2,4-D amine, which may injure some grasses grown for seed. Injury potential varies greatly with geographic location and crop species and is influenced by application rate and timing. Consider your experience with 2,4-D to evaluate the risk of injury versus the benefits of weed control.

Caution For established grasses only. Risk of crop injury increases with increasing rate and later application. Do not use on bentgrass unless injury can be tolerated. Carefully follow label instructions on crop rotation if land is to be taken out of grass seed production. Do not apply by air during an air temperature inversion. Some grass-seed straw export markets will not accept straw from grasses treated with clopyralid containing products.

Site of action (both) Group 4: synthetic auxin

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

clopyralid + MCPA (Curtail M)

Rate 0.092 to 0.184 lb ae/A clopyralid + 0.5 to 1 lb ae/A MCPA (1.75 to 3.5 pints/A Curtail M)

Time Apply in spring before boot stage and/or as a postharvest fall treatment. To control late-emerging Canada thistle, treat preharvest after grass seed is fully developed; apply to Canada thistle after most basal leaves emerge but before bud stage.

Remarks Curtail M contains MCPA ester which may injure some grasses grown for seed. Injury potential varies greatly with geographic location and crop species and is influenced by application rate and timing. Consider your experience with MCPA to evaluate the risk of injury versus the benefits of weed control.

Caution For established grasses only. Potential for crop injury increases with increasing rate and later stages of application. Do not use on bentgrass unless injury can be tolerated. Carefully follow label instructions on crop rotation if land is to be taken out of grass seed production. Do not apply by air during an air temperature inversion. Some grass-seed straw export markets will not accept straw from grasses treated with clopyralid containing products.

Site of action (both) Group 4: synthetic auxin

Chemical family (clopyralid) pyridine; (MCPA) phenoxy acetic acid

dicamba (several trade names) + 2,4-D or MCPA or tribenuron methyl (several trade names)

Rate 0.25 to 1 lb ae/A dicamba + 0.5 to 1.5 lb ae/A 2,4-D or MCPA or 0.008 to 0.016 lb ai/A tribenuron

Time New seedlings: apply to new grass after it reaches three-leaf stage but before jointing. Do not exceed 0.5 lb ae/A dicamba. Established stands: apply before jointing stage. Apply when temperatures are 55 to 75°F. Fall applications give better control of perennial, biennial, and winter annual broadleaf weeds after considerable foliage has developed. Do not exceed 1 lb ae/A dicamba.

Remarks Refer to individual product labels for specific rate, timing, and application directions. See specific remarks for tribenuron below.

Caution Use precautions to prevent drift. Some perennial ryegrass varieties are sensitive to tribenuron and may be injured. On newly established grass seed stands, combinations of dicamba + MCPA result in greater crop safety than dicamba + 2,4-D tank-mixes. See individual labels for grazing restrictions, but in general for 2,4-D, 7 days; for MCPA, 14 days (see labels); for dicamba, 7 days for up to 0.5 lb ae/A and 21 days if over 0.5 lb ae/A for lactating dairy cows (see labels). Do not apply after grass seed crop reaches jointing stage. Do not use more than 0.5 lb ae/A dicamba on bentgrass unless injury can be tolerated.

Site of action (dicamba, 2,4-D, and MCPA) Group 4: synthetic auxin; (tribenuron methyl) Group 2: acetolactate synthase (ALS) inhibitor

Chemical family (dicamba) benzoic acid; (2,4-D and MCPA) phenoxy acetic acid; (tribenuron methyl) sulfonylurea

halosulfuron (Sandea)

Rate 0.031 to 0.062 lb ai/A (0.67 to 1.33 oz/A Sandea)

Time Apply in spring for postemergence control of yellow nutsedge and broadleaf weeds in established creeping bentgrass, Kentucky bluegrass, fine fescues, tall fescue and perennial ryegrass.

Remarks A sequential treatment may be necessary to control yellow nutsedge 6 to 10 weeks after the initial application. Always apply with a NIS at 0.5% v/v.

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

Chemical family Pyrazole

MCPA amine, MCPA ester, or bromoxynil (several trade names)

Rate 0.5 to 1 lb ae/A MCPA; 0.25 to 0.5 lb ai/A bromoxynil

Time Eastern Oregon: after new grass reaches three- to five-leaf stage. Western Oregon: apply MCPA at 0.5 lb ae/A on fall-seeded stands after two-leaf stage. Established stands: apply in fall or spring but before boot stage. Washington and Idaho seedling grasses: apply MCPA after grass tillers.

Remarks For newly established grass seed in eastern and western Oregon and established stands. Bromoxynil can be applied any time after grass emerges and before weeds are larger than listed on label (generally, four to six leaves).

Caution A 7-day waiting period is required after MCPA application before grazing. MCPA may injure bentgrass at higher application rates. Grass seedling root development may be inhibited when MCPA is applied to early growth stages; therefore, frequent irrigation is important to help grasses establish. Do not apply bromoxynil to cool-season grasses if air temperature is above 80°F, because crop injury may be unacceptable. Do not graze or feed straw from fields treated with bromoxynil.

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

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

saflufenacil (Sharpen)

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

Time Cool-season grasses: Apply to new grass seedings after the first tiller is fully established in the fall or spring. Apply anytime to established grasses in fall or spring after greenup until boot stage.

Remarks A methylated seed oil is required for optimum efficacy. See label for more information on adjuvants and tank-mixes.

Caution Do not exceed 4 or 6 fl oz/A per year on seedling or established grass seed stands, respectively. Sequential applications must be separated by at least 14 days; do not apply more than 2.0 fl oz/A per application. Sharpen may cause transitory injury to cool-season grasses under certain conditions, but new growth is normal and vigor is not reduced. The preharvest interval for seed is 50 days after application. There are no feeding or grazing restrictions.

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

Chemical family Pyrimidindione

tribenuron methyl (several trade names)

Rate 0.008 to 0.016 lb ai/A

Time Fall or spring, when broadleaf weeds are actively growing.

Remarks May be used on seedling or established stands of perennial ryegrass, tall fescue, annual ryegrass, bluegrass, bentgrass, fine fescue, and orchardgrass. Use only the 0.008 lb ai/A rate on tall fescue and perennial ryegrass. Spring applications on tall fescue must be before stems start elongating. Use the 0.016 lb ai/A rate on established annual ryegrass, bluegrass, bentgrass, fine fescue, and orchardgrass. Always use a nonionic surfactant at 1 quart/100 gal. Adding 2,4-D at 0.25 to 0.5 lb ae/A plus liquid nitrogen fertilizer at 4 gal/100 gal aids weed control and crop safety.

Caution Some perennial ryegrass varieties are sensitive to tribenuron and may be injured. Do not apply to grass that is under stress. Do not feed or graze treated grass seed for 60 days after applying.

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

Chemical family Sulfonylurea

Bedstraw and Canada Thistle Management

carfentrazone (Aim EC)

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

Time Apply to actively growing weeds when they are small. May be applied before seeding and up to jointing stage of crop.

Remarks See label for specific tank-mixes and adjuvant recommendations. Apply in at least 10 gal/A of spray solution. Good spray coverage is essential for control.

Caution Do not exceed 0.093 lb ai/A of Aim per growing season.

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

Chemical family Triazinone

fluroxypyr (Starane Ultra)

Rate 0.11 to 0.14 lb ai/A fluroxypyr (0.3 to 0.4 pints/A Starane Ultra)

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. Apply to two-leaf seedling grasses up to early boot stage, or to established grasses before early boot stage.

Remarks Do not exceed 0.7 pints/A per growing season or 2 applications per season, and separate applications by 14 days.

Caution There are no grazing restrictions after applying Starane Ultra. Do not harvest grass for hay or silage from treated area within 7 days of application. Withdraw meat animals from treated forage at least 2 days before slaughter.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

fluroxypyr + bromoxynil (Starane NXT)

Rate 0.063 to 0.125 lb ai/A fluroxypyr + 0.26 to 0.5 lb ai/A bromoxynil (14 to 27.4 oz/A Starane NXT)

Time For best performance, apply to emerged and actively growing broadleaf weeds less than 2 inches high or 1 inch wide. Apply to two-leaf seedling grasses up to early boot stage or to established grasses before early boot stage. Reduced weed control may occur when applied in cold conditions. See label for recommended environmental conditions for timing of application.

Remarks Seedling grasses tolerant to Starane NXT include Kentucky bluegrass, fescue, orchardgrass, and perennial ryegrass. Established grasses tolerant to Starane NXT include bluegrass, fescue, perennial ryegrass, and bermudagrass.

Caution Do not plant any nonlabeled rotation crop within 120 days of application. Do not feed treated grasses to livestock or allow treated area to be grazed.

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

Chemical family (fluroxypyr) pyridine; (bromoxynil) nitrile

fluroxypyr + clopyralid (WideMatch)

Rate 0.094 to 0.125 lb ai/A fluroxypyr + 0.094 to 0.125 lb ai/A clopyralid (1 to 1.33 pints/A WideMatch)

Time For best performance, apply to emerged and actively growing broadleaf weeds less than 4 inches tall or before vining. Apply to two-leaf seedling grasses up to early boot stage or to established grasses before early boot stage. Weed control may be reduced when applied in cold conditions. See label for recommended environmental conditions at application.

Remarks Controls broadleaf weeds including kochia, wild buckwheat, Canada thistle, volunteer potato, and prickly lettuce. Tank-mix compatible with MCPA, dicamba, bromoxynil, or 2,4-D. Tank-mixes help to broaden annual-weed control spectrum but may reduce efficacy on perennial weeds such as Canada thistle. Do not tank mix with 2,4-D, MCPA, or dicamba unless the risk of crop injury is acceptable.

Caution Do not apply to bentgrass unless crop injury can be tolerated. See label for rotation restrictions on other crops. Do not harvest grass for hay or silage from treated area within 7 days of application. Withdraw meat animals from treated forage at least 2 days before slaughter. Some grass-seed straw export markets will not accept straw from grasses treated with products containing clopyralid.

Site of action (both) Group 4: synthetic auxin

Chemical family (both) pyridine

Field Bindweed Management

quinclorac (Paramount)

Rate 0.248 to 0.375 lb ai/A (5.3 to 8 oz/A Paramount)

Time Apply in fall after harvest but before a killing frost. Field bindweed should be actively growing and at least 4 inches long.

Remarks May be used on Kentucky bluegrass, annual and perennial ryegrass, and fine and tall fescue seed fields. Adequate soil moisture and/or light rain after application is required for root uptake. Repeat applications are necessary to maintain adequate control. 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.

Caution Do not graze treated fields. Do not feed treated grasses, forage, hay, silage, straw, seed, or seed screenings to livestock. Do not apply by air west of the Cascades or in Spokane County, WA.

Site of action Group 4: synthetic auxin

Chemical family Quinoline carboxylic acid

Annual Bluegrass Management

glufosinate-ammonium (several trade names)

Oregon only, grass weeds

Rate Fall broadcast: use 0.18 lb ai/A (10 oz/A Rely 280, Reckon 280, or Glufosinate 280); Spring broadcast: use 0.30 to 0.37 lb ai/A (16.5-20 oz/A Rely 280, Reckon 280, or Glufosinate 280); Spring directed, shielded spray: use 1.0 to 1.5 lb ai/A (55-82 oz/A Rely 280, Reckon 280, or Glufosinate 280)

Time Apply to established and seedling fields. Treat newly established fields after the first tiller has developed and prior to December 1. Spray established fields when crop begins active growth in early spring, usually prior to April 1.

Remarks One spring broadcast application can be made following a fall broadcast application. Use in the spring as a rescue treatment in established crops or if fall-applied herbicide programs have not been adequate. Glufosinate controls or suppresses annual and roughstalk bluegrass, mannagrass, and some brome species.

Caution Glufosinate may severely injure some crop species. Do not broadcast apply glufosinate on fine fescue, orchardgrass, or Poa spp. grown for seed. Directed, shielded sprays are suggested for fine fescues, orchardgrass or Poa spp. grown for seed. See specific restrictions and directions on the glufosinate OR SLN labels. Consult a crop adviser or an OSU Extension specialist for more information. Growers assume all liability for crop injury when using glufosinate in grasses grown for seed. Do not graze treated fields for one year following application.

Site of action Group 10: glutamine synthase inhibitor

Chemical family Phosphinic acid