Winter Annual Grasses and Broadleaf Weeds in Established Stands

asulam (Asulox)

Rate 1.24 to 1.5 lb ai/a (3 to 3.6 pints/a Asulox)

Time Apply when weeds are less than 3 inches tall.

Remarks SLN WA-100008, ID-130002, and OR-140002. Apply as a postemergent application. Symptoms are slow to develop and several weeks are needed for control.

Caution Do not disturb soil 7 days prior and 7 days after an application.

Site of action Group 18: inhibits DHP synthase

Chemical family Carbamate

carfentrazone (Aim EC)

Rate 0.008 to 0.04 lb ai/a (0.5 to 2.5 oz/a Aim EC)

Time Apply Aim EC in the fall after the crop is dormant or in the spring before spring growth starts.

Remarks Apply as a broadcast spray to dormant alfalfa that has been established for at least 1 year. See label for tank mixes. Use rates up to 2.5 oz in 10 gal of water for optimal control. Always add an adjuvant. See Aim EC label for recommended additives.

Caution Do not harvest stands grown for seed for 3 days after application. Do not apply more than 3.8 oz of Aim EC per year.

Site of Action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Triazolinone

diuron (Karmex or Direx 4L)

Rate 1.2 to 2.4 lb ai/a (1.5 to 3 lb/a product)

Time Apply at start of dormancy (late October through early December).

Remarks Apply as a broadcast spray to dormant alfalfa established more than 1 year. Not very effective on downy brome (cheatgrass) or volunteer cereals.

Caution Do not use on soils with less than 1% organic matter. Do not apply to snow-covered or frozen soil. Do not replant treated area to any crop within 2 year of application.

Site of action Group 7: photosystem II inhibitor

Chemical family Substituted urea

flumioxazin (Chateau)

Rate 0.1275 lb ai/a (4 oz/a Chateau)

Time Apply preemergence to the weeds.

Remarks Special local need labels WA-10003 and 120012. Applications should be made as soon as possible after cutting and removing alfalfa, to minimize crop injury. Flumioxazin will burn treated leaves and stems. A second application can be made 60 days after the first application. Will only give fair control of many annual grasses. If weeds are present when applications are made after the last harvest in the fall or when the alfalfa is dormant, apply with paraquat to burn down weeds present.

Caution Do not harvest or graze within 25 days of application. Do not make second application within 60 days of the first application. Do not exceed 8 oz of Chateau during a single growing season.

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

Chemical family N-phenylphthalimide

hexazinone (Velpar DF and L)

Rate 1 to 1.5 lb ai/a (1.33 to 2 lb/a Velpar DF; 4 to 6 pints/a L)

Time Apply in fall after crop is dormant and before spring growth exceeds 2 inches.

Remarks See supplemental label for Walla Walla county growers. Use lower rate on coarse, sandy soils low in organic matter. Apply to alfalfa established at least one growing season. Results are best if applied before, or soon after, weeds emerge (before weeds are 2 inches tall or across). If weeds are emerged, use a surfactant.

Caution A restricted-use herbicide in WA for the protection of groundwater. Do not graze or harvest (cut for hay) within 30 days after application. Do not apply to alfalfa growing under stress from insect, disease, winter injury, or other factors. Do not use on fields with sandy loam or loamy sands having less than 1% organic matter. Very heavy rain or more than 0.5 inch of irrigation soon after application may result in crop injury or herbicide nonperformance. Hexazinone persists in soil up to 24 months. Read label for crop rotation restrictions and other cautions.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazinone

hexazinone + diuron (Velpar Alfamax Gold DG)

Rate (0.231 to 0.462 lb ai/a hexazinone + 0.55 to 1.12 lb ai/a diuron (16 to 32 oz/a product)

Time Apply in fall after crop is dormant and before spring growth exceeds 2 inches.

Remarks Apply to alfalfa established for at least one year.

Caution A restricted-use herbicide in WA for the protection of groundwater. Do not graze or harvest (cut for hay) within 30 days after application. Do not apply to alfalfa growing under stress from insect, disease, winter injury, or other factors. Do not use on fields with sandy loam or loamy sands having less than 1% organic matter. Very heavy rain or more than 0.5 inch of irrigation soon after application may result in crop injury or herbicide nonperformance. Hexazinone persists in soil up to 24 months. Read label for crop rotation restrictions and other cautions.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazinone

imazamox (Raptor, Vulture)

Rate 0.03125 to 0.047 lb ai/a (4 to 6 oz/a Raptor or Vulture)

Time Apply to established alfalfa in the fall, in the spring to dormant or semidormant alfalfa (less than 3 inches of regrowth), and when most weeds are 1 to 3 inches tall or across, and before alfalfa buds form.

Remarks Adding an adjuvant (nonionic surfactant or crop oil concentrate), and a liquid fertilizer solution or ammonium sulfate solution enhances weed control. Temporary height reduction or leaf yellowing may occur soon after application. Weeds under stress are harder to control. Apply at least 1 hour before rain or overhead irrigation.

Caution Before using, note recropping restrictions. Some crops cannot be planted within 26 months of application.

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

Chemical family Imidazolinone

imazethapyr (Pursuit)

Rate 0.047 to 0.094 lb ai/a (3 to 6 oz/a Pursuit)

Time Apply to established alfalfa in the fall, in spring to dormant or semidormant alfalfa (less than 3 inches of regrowth), and when most weeds are actively growing and 1 to 3 inches tall or across.

Remarks Adding an adjuvant (nonionic surfactant or crop oil concentrate), and a liquid fertilizer solution is required. Temporary height reduction or slight leaf yellowing may occur soon after application. Weeds under stress are less susceptible to control. Apply at least 1 hour before rain or overhead irrigation.

Caution Do not feed, graze, or harvest alfalfa for 30 days after application. See recropping restrictions before use. Some crops cannot be planted within 40 months of application. Use only rotational crops harvested at maturity for feed or food.

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

Chemical family Imidazolinone

metribuzin (Dimetric EXT, TriCor 75 DF, TriCor 4F)

Rate 0.25 to 1 lb ai/a (0.33 to 1.33 lb/a DF; 0.5 to 2 pints/a 4F)

Time Apply in fall after crop is dormant and before spring growth starts.

Remarks Consult label for the product used. Broadcast spray dormant alfalfa established 1 year or more. Use the 0.25-lb rate of Sencor if common chickweed is the only target.

Caution Do not use on sand. Do not use Sencor on soils with a pH greater than 8.2. Do not apply on snow-covered or frozen ground. Use lower rates on coarse, sandy soils or soils low in organic matter. Do not graze or harvest within 28 days after application. Stunting and chlorosis may occur, particularly in nondormant alfalfa. Stress (which may be caused in part by low fertility, disease, insects, overcutting, drought, or frost) may increase the possibility of crop injury. Avoid overlapping because injury may occur. See herbicide label for recropping recommendations.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazinone

norflurazon (Solicam DF)

Rate 1 to 2 lb ai/a (1.27 to 2.58 lb/a Solicam DF)

Time Apply no earlier than 5 months after crop emerges, or to dormant alfalfa before weeds emerge.

Remarks Use lower rates on coarse and medium soils, higher rate on fine soils. At least 0.5 inch of overhead moisture is needed to move herbicide into soil. Fall or winter application is recommended in nonirrigated areas with less than 15 inches annual moisture (rain and snow combined), or less than 4 inches of spring rain. Does not control established weeds. Established weeds or weeds that emerge before activation may be controlled with a labeled postemergence herbicide.

Caution Do not apply to seedling alfalfa earlier than 5 months after planting. Do not exceed 2 lb ai/a per year. Note rotation restrictions. Before crop rotation, bioassay soils that contain more than 65% sand. Rotation crops can be planted if no signs of phytotoxicity are observed in bioassay plants for 4 months after emergence.

Site of action Group 12: bleaching; inhibitor of carotenoid biosynthesis

Chemical family Pyridazinone

paraquat (Gramoxone SL 2.0, Parazone 3L)

Rate Firestorm: use 0.49 to 1 lb ai/a (1.3 to 2.7 pints/a product). Gramoxone Inteon: use 0.5 to 0.75 lb ai/a (2 to 3 pints/a product). Add nonionic surfactant with at least 75% surface-active agent at 16 to 32 fl oz/100 gal, or crop oil concentrate with 15 to 20% approved emulsifier at 1 gal/100 gal spray mix.

Time Apply after seed harvest when crop is dormant, before spring growth starts.

Remarks Apply soon after weeds germinate. Alfalfa should be dormant, and regrowth following harvest not more than 2 inches high. Control decreases as weed size increases. Use 20 gal/a or more of water carrier for ground application. Paraquat is a contact herbicide. Combining with one of the residual herbicides usually gives knockdown plus residual control. SLN labels available for OR (120014, 140009, 180005), WA (120009, 130011, 180003), and ID (120002, 140004 and 180003).

Caution A restricted-use herbicide. Do not pasture animals in treated fields. Do not graze, cut, or harvest within 42 days of application. Do not apply more than once per season. Follow safety precautions on the labels.

Site of action Group 22: photosystem I electron diversion

Chemical family Bipyridilium

pendimethalin (Prowl or Stealth)

Rate Prowl H2O: use 0.95 to 3.8 lb ai/a (1 to 4 quarts/a product). Prowl 3.3EC and Stealth: use 1 to 4 lb ai/a (1.2 to 4.8 quarts/a product).

Time Apply to established alfalfa between January 15 and April 30 but before dodder germinates.

Remarks Active special local needs labels include ID-060016 and OR-070027 for Stealth. Controls most annual grasses and certain broadleaf weeds, in addition to dodder, as they germinate. Processed seed must be labeled "Not for human or animal consumption" at the processing plant, and all seed screenings must be disposed of in a way that they cannot be distributed or used for food or feed. For optimum dodder control, use 3 to 4 quarts/a of Prowl H2O or 3 to 4.8 quarts/a of Prowl 3.3 or Stealth.

Caution Do not apply this rate to seedling alfalfa. Do not graze or harvest alfalfa for hay after application. Do not use screenings from seed processing as feed for livestock. Do not use harvested seed for sprouting. Refer to main labels for crop rotation restrictions.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

simazine (Simazine 4L)

Washington only

Rate 0.8 to 1.6 lb ai/a (0.8 to 1.6 quarts/a)

Time Apply to alfalfa in fall, after harvest but before ground freezes.

Remarks Special local needs labels WA-900040 and WA-090015. Broadcast spray on alfalfa established 1 year or more. Do not apply to frozen ground. Apply only once per year. Processed seed must be labeled "Not for human or animal consumption" at the processing plant, and all seed screenings must be disposed of in a way that they cannot be distributed or used for food or feed.

Caution Do not use on sand, loamy sand, or gravelly soil. Do not use seed for sprouting. Do not graze treated area or cut for hay after treatment. Do not cultivate before or after simazine application. Do not plant any crop except corn the year after application, or crop may be injured.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazine

S-metolachlor (Dual Magnum)

Oregon only

Rate 2.5 to 3.2 lb ai/a (2.65 to 3.332 pints/a Dual Magnum)

Time Apply and incorporate prior to weed emergence.

Remarks SLN OR-040007. This is an indemnified label that is available at www.farmassist.com. Users of this product assume all risk of crop injury, crop yield reduction and crop loss, and release Syngenta Crop Protection from all liability. Incorporate metolachlor uniformly in the top 3 inches of the soil by cross tillage (twice over the field).

Caution Do not use tailwater from first flood, or furrow irrigation of treated fields to treat nontarget crops, unless 0.5 inch of rainfall has occurred between application and the first irrigation. No portion of the crop may be may be used or distributed for food or feed for 1 year after application. All seed screenings must be disposed of in such a manner that the screenings cannot be distributed for food or feed purposes.

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

Chemical family Chloroacetamide

terbacil (Sinbar)

Rate 0.4 to 1.2 lb ai/a (0.5 to 1.5 lb/a Sinbar)

Time Apply to dormant alfalfa after frost, before January 1.

Remarks Broadcast spray on dormant alfalfa established 1 year or more. Use lower rate on coarse, sandy soils, or on soils low in organic matter.

Caution Do not use on sand, loamy sand, or gravelly soil. Do not use on soils containing less than 1% organic matter. Do not apply on snow-covered or frozen ground. Do not replant treated areas to any crop within 2 years of last application.

Site of action Group 5: photosystem II inhibitor

Chemical family Uracil