Summer Annual Grasses in Established Stands

clethodim (Select 2EC, Select Max, Intensity, or Intensity One)

Rate Select 2EC, or Intensity: use 0.094 to 0.125 lb ai/a (6 to 8 fl oz/a product). Select Max or Intensity One: use 0.07 to 0.24 lb ai/a (9 to 32 fl oz/a product).

Time Apply to actively growing annual or perennial grasses in the labeled growth stage.

Remarks For grass control only. See label for specific weed species and weed size. Always add a crop oil concentrate containing at least 15% emulsifier at 1% v/v in the finished spray volume. Adding ammonium sulfate improves control of difficult-to-control grasses. Clethodim is most effective on actively growing grasses before they reach maximum size indicated on label. Use higher rate under heavy grass pressure and/or if annual bluegrass is more mature.

Caution Control may be erratic on grasses stressed by drought, temperature extremes, insect damage, herbicide injury, or other factors, or if grasses are larger than indicated on label. Do not apply if rain is expected within 1 hour after application. Do not apply within 15 days of grazing, feeding, or harvesting for forage or hay. Do not exceed 0.5 lb ai/a per season (32 fl oz/a of Select or 64 fl oz/a of Select Max).

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Cyclohexanedione

fluazifop (Fusilade DX)

Rate 0.125 to 0.188 lb ai/a (0.5 to 0.75 pints/a product)

Time Apply to actively growing, susceptible grasses in the labeled growth stage.

Remarks Special local needs labels OR-040006, ID-950006, and WA-040007. Add a crop oil concentrate at 0.5% to 1% concentration or a nonionic surfactant at 0.25% to 0.5% concentration. Results often are erratic on grasses stressed from lack of vigor, drought, high temperatures, low fertility, or other factors. More mature grasses and quackgrass can be controlled but may require two applications. Will not control annual bluegrass or any of the fine fescues. Fluazifop is often weak on foxtails and perennial bluegrass.

Caution Do not feed treated forage to livestock.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Aryloxyphenoxypropionate

quizalofop (Assure II)

Rate 0.034 to 0.825 lb ai/a (5 to 12 oz/a Assure II)

Time Apply to actively growing annual or perennial grasses in the labeled growth stage.

Remarks See label for specific herbicide rates, weed species, and weed size. Under arid conditions, use higher rate for the target grass weed. Always include a nonphytotoxic crop oil concentrate at 1% v/v or a nonionic surfactant at 0.25% v/v. Crop oil concentrate is preferred in arid areas. Will not control annual bluegrass or fine fescue. Control may be reduced on grasses stressed from lack of moisture, cold, herbicide injury, or insect injury or disease.

Caution Do not apply within 14 days of anticipated bloom. Do not use any part of crop (seed, sprouts, screenings, hay, forage, etc.) for animal or human consumption. Do not exceed two applications or 0.17 lb ai/a (25 oz/a product) per season.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Aryloxyphenoxypropionate

sethoxydim (Poast or Poast Plus)

Rate 0.19 to 0.47 lb ai/a (1 to 2.5 pints/a Poast)

Time Apply to actively growing annual or perennial grasses at growth stage listed on the label.

Remarks See label for specific herbicide rates, weed species, and weed size. Always add a nonphytotoxic oil concentrate to the spray tank at 2 pints/a of alfalfa treated. Sethoxydim is most effective on actively growing grasses before they have been cut, and before they reach the maximum size indicated on the label. Larger, more mature grasses can be controlled, but two applications may be required. Will not control annual bluegrass or any of the fine fescues.

Caution Control often is erratic on grasses stressed by drought, temperature extremes, insect damage, herbicide injury, or other factors. Do not apply if rain is expected within 1 hour after application. Do not exceed 1.22 lb ai/a in one season.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Cyclohexanedione

trifluralin (Treflan TR-10)

Rate 2 lb ai/a (20 lb/a Treflan TR-10)

Time Apply before weeds emerge.

Remarks Within 3 days, trifluralin must be activated by a single rain or overhead sprinkler irrigation of 0.5 inch after application, or it must be mechanically incorporated with equipment that will ensure thorough soil mixing with minimal damage to the alfalfa. Will not control emerged weeds.

Caution If established alfalfa is to be rotated to another crop the year after application, plant only those crops for which trifluralin can be applied as a preplant treatment, or injury may result.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline