Broadleaf Weeds

aminocyclopyrachlor (Method)

Rate 4 to 18 oz/a

Time Apply preemergence or postemergence when weeds are actively germinating or growing

Remarks Do not apply where roots of woody plants extend unless injury or loss can be tolerated. The root zone can extend beyond the canopy. Even low rates can kill nontarget tree and shrub species. Sensitive trees include, but are not limited to, ponderosa pine, Douglas-fir, Norway spruce, white pine, aspen, Chinese tallow, cottonwood, honey locust, magnolia, poplar, redbud, silver maple, and willow. Individual plant treatments are allowed on sites transecting areas grazed by livestock.

Site of action Group 4 synthetic auxin

Chemical family Phenoxy acetic acid

aminocyclopyrachlor + chlorsulfuron (Perspective)

Rate 0.7 to 3.2 oz/a aminocyclopyrachlor + 0.3 to 1.3 oz/a chlorsulfuron (1.75 to 8 oz/a of product)

Time Apply to broadleaf weeds in fall or spring.

Remarks Adjuvants can be used; these include methylated seed oils 0.5 to 1% v/v, nonionic surfactants at 0.25 to 1% v/v, and crop oil concentrates at1%v/v. Can be applied using an invert emulsion rather than water.

Caution Even low rates can kill nontarget tree and shrub species, so avoid application to sensitive species within a distance equal to their height. Do not allow spray to drift off target. Can injure several grass species including bromes, as well as basin wildrye.

Site of action Group 4 synthetic auxin (aminocyclopyrachlor) Group 2: ALS inhibitor (chlorsulfuron)

Chemical family Phenoxy acetic acid (aminocyclopyrachlor); sulfonylurea (chlorsulfuron)

aminopyralid (Milestone)

Rate 0.75 to 1.75 oz ae/a (3 to 7 fl oz/a Milestone)

Time Apply to actively growing weeds. Consult label for specific weeds.

Remarks Effective on knapweeds, biennial thistles, Canada thistle, perennial sowthistle, horseweed (marestail) and hawkweed. A nonionic surfactant at 1 to 2 quarts/100 gal spray enhances control under adverse environmental conditions. Application rate depends on weed species and stage of growth.

Caution Do not allow drift to desirable vegetation. Do not exceed 7 fl oz/a Milestone per year.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

aminopyralid + metsulfuron (Opensite)

Rate 1 to 3.3 oz product/a

Time Postemergent to young, actively growing plants.

Remarks Effective on some species within Asteraceae, Brassicaceae, Boraginaceae, and Fabaceae but will control species from other plant families as well.

Caution Do not use plant residues for compost or mulch if the compost will be applied to susceptible broadleaf plants such as potato, tomato, and peas.

Site of action Group 4: synthetic auxin, Group 2: acetolactate synthase (ALS) inhibitor

Chemical family (aminopyralid) Pyridine ; (metsulfuron) Sulfonylurea

aminopyralid + triclopyr (Capstone)

Rate 4 to 6 pints product/a

Time Postemergent to young, actively growing plants.

Remarks Effective on some species within Asteraceae, Brassicaceae, Boraginaceae, and Fabaceae but will control some species from other families as well.

Caution Do not use plant residues for compost or mulch if the compost will be applied to susceptible broadleaf plants such as potato, tomato, and peas

Site of action Group 4: synthetic auxin

Chemical family Pyridine

bromoxynil (Buctril)

Rate 0.25 to 0.5 lb ai/a

Time Postemergent, when weeds are actively growing.

Remarks Apply to broadleaf weeds before four-leaf stage or less than 2 inches high or 1 inch across, whichever comes first. Adding surfactant or crop oil concentrate may improve broadleaf weed burn down under cool, dry conditions.

Caution Do not allow grazing in treated areas. Do not apply through backpack or hand-held application equipment.

Site of action Group 6: photosystem II inhibitor

Chemical family Nitrile

chlorsulfuron (Telar)

Rate 0.75 to 2.25 oz ai/a (1 to 3 oz/a)

Time Apply preemergence or postemergence to weeds. For best results, apply postemergence to young actively growing weeds any time except when ground is frozen.

Remarks Adequate moisture (rain) is needed to activate herbicide. In postemergence applications, a nonionic surfactant must be added at 1 quart/100 gal spray.

Caution Agitation is required. Do not apply to soils saturated with moisture or during periods of intense rain. Degree of control and duration of effect varies with amount of chemical applied, soil texture, soil pH, soil organic matter, weed size, rain, and other factors.

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

Chemical family Sulfonylurea

clopyralid (Transline)

Rate 0.09 to 0.5 lb ae/a

Time After weeds have emerged and, depending on species, up to bud stage.

Remarks Effective on weeds in the Asteraceae (sunflower), Polygonaceae (knotweed), and legume families. Plants should be actively growing at time of treatment. Wet foliage at time of treatment may decrease control.

Caution Do not contaminate irrigation ditches or water for irrigation or domestic use. Do not allow spray drift to contact potatoes, beans, or certain other crops.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

clopyralid + 2,4-D (Curtail)

Rate 2 to 4 quarts/a Curtail

Time Apply after most knapweed rosettes have emerged but before flower stem elongates. Apply to Canada thistle before bud stage.

Remarks Effective on diffuse and spotted knapweed and Canada thistle. Also controls many other weeds in the composite and legume families.

Caution Do not contaminate irrigation ditches or water for irrigation or domestic use. Do not allow spray drift to contact potatoes, beans, or certain other crops.

Site of action (both) Group 4: synthetic auxin

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

dicamba (Banvel, Trooper, Vanquish, Rifle, or Clarity)

Rate 0.25 to 2 lb ai/a

Time Apply to actively growing vegetation.

Remarks Controls many annual and perennial broadleaf weed species as well as brush. Other herbicides often are combined and sold under a variety of trade names. Consult label for rates, times of application, use restrictions, and preparations for each of these proprietary mixtures.

Caution Do not use in areas where roots of desirable vegetation may extend.

Site of action Group 4: synthetic auxin

Chemical family Benzoic acid

diflufenzopyr + dicamba (Overdrive)

Rate 0.175 to 0.35 lb ae/a (4 to 8 oz/a)

Time Apply to actively growing broadleaf weeds.

Remarks Controls many annual, biennial, and perennial broadleaf weeds and vine species, including biennial thistle, Canada thistle, kochia, and marestail (horseweed). Rate depends on weed species and growth stage at time of treatment. For improved uptake, use a nonionic surfactant or a methylated seed oil on hard-to-control perennials and waxy-leaf species or when weeds are under moisture or temperature stress.

Caution Do not plant any crop within 30 days of application. Do not exceed 10 oz/a of Overdrive per season.

Site of action (diflufenzopyr) Group 19: inhibits indole-acetic acid transport; (dicamba) Group 4: synthetic auxin

Chemical family (diflufenzopyr) semicarbazone; (dicamba) benzoic acid

flumioxazin (Payload)

Rate 0.25 to 0.38 lb ai/a (8 to 12 oz/a)

Time Preemergence, to bare soil, or postemergence.

Remarks Broadleaf weed control but weak on most grasses. Do not exceed 0.38 lb ai/a per application or 0.75 lb ai/a per year. Moisture is required to activate preemergence applications. Adding an adjuvant enhances postemergence applications; good spray coverage is required.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family N-phenylphthalimide

fluroxypyr (Vista XRT)

Rate 0.125 to 0.5 lb ae/a

Time Apply when weeds are small and/or actively growing.

Remarks Apply in spray volume of 3 gal/a or more by air or 5 gal/a or more by ground. Do not exceed 40 gal/a total spray volume. Spot treatments may be applied with a calibrated boom or hand sprayer. Only weeds emerged at treatment are controlled. Control may decrease if foliage is wet at time of application. Grasses are tolerant of fluroxypyr, but larger kochia is effectively controlled.

Caution Do not apply when weather conditions favor drift from treated areas. Do not exceed 0.5 lb ae/a (2.67 pints/a) per year.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

isoxaben (Gallery)

Rate 0.5 to 1 lb ai/a

Time Apply before germination.

Remarks Area should be free from established weeds before application.

Site of action Group 21: inhibits cell wall synthesis Site B

Chemical family Benzamide

MCPA (several products)

Rate 3 lb ai/a

Time Spray to wet weeds thoroughly when in bud to early bloom and again on fall regrowth.

Remarks Controls Canada thistle, whitetop, and meadow buttercup.

Caution Do not cut forage on treated areas within 7 days of treatment.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

metsulfuron (Escort)

Rate 0.3 to 1.8 oz ai/a (0.5 to 3 oz/a)

Time For best results, apply postemergence to young, actively growing weeds or brush. Selective to many grasses. May combine with other products to broaden weed-control spectrum.

Remarks For postemergence applications, include a nonionic or silicone surfactant at 0.25% by volume. Good coverage is essential for control.

Caution Agitation required. Do not allow spray to drift to crops or other valuable plants or trees.

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

Chemical family Sulfonylurea

picloram (Tordon)

Rate 0.125 to 1 lb ae/a

Time Apply to foliage of actively growing weeds and brush.

Remarks Picloram has soil-residual activity. It is formulated in several mixtures including combinations with 2,4-D.

Caution Most formulations are restricted-use herbicides. Follow all use restrictions and precautions on label.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

picloram + 2,4-D (Graslan)

Rate 0.66 to 2.66 pints/a

Time Apply to foliage of actively growing weeds. Use 0.66 to 1.25 pints/a in early to mid-spring when weeds are less than 3 inches tall and higher rates mid to late season when weeds are over 3 inches to flowering.

Remarks Picloram has soil-residual activity.

Caution Restricted-use herbicide: Follow all use restrictions and precautions on label.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

quinclorac (Paramount)

Rate 4 to 6 oz ai/a (5.3 to 8 oz/a)

Time Apply to actively growing weeds.

Remarks Timing and rate of application depends on target weeds. Controls field bindweed, leafy spurge, sowthistle, Canada thistle, and clovers. Must add methylated seed oil at 1 to 2 pints/a or crop oil concentrate at 2 pints/a. Plant uptake is through foliage and roots. Rain after application is important for soil uptake.

Caution Do not exceed 12 oz ai/a per calendar year. Do not allow to drift to sensitive crops. Do not apply to water or to irrigation ditches or areas that channel water entering cropland.

Site of action Group 4: synthetic auxin

Chemical family Quinoline carboxylic acid

tebuthiuron (Spike 80 DF)

Rate 1 to 4 lb ai/a

Time Apply in fall east of the Cascades and in spring west of the Cascades.

Remarks Use higher rates for perennial weed control, lower rates for annual weed control and maintenance treatments.

Caution Spike will kill trees, shrubs, and other desirable vegetation if roots extend into the treated area.

Site of action Group 7: photosystem II inhibitor

Chemical family Substituted urea

triclopyr (Garlon 3A)

Rate 0.25 to 3 gal/a

Time Apply when woody plants and weeds are actively growing. The ester formulation may be used in the dormant season. See label for instructions.

Remarks Controls certain perennial broadleaf weeds and woody plants. Rates depend on weed species, stage of maturity, and environmental conditions. If using lower rates on hard-to-control species, they may resprout a year later.

Caution See label for grazing restrictions.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

triclopyr + 2,4-D (Crossbow)

Rate 1 quart to 4 gal/a, depending on weed species

Time Apply during warm weather, when brush and weeds are actively growing.

Remarks Controls most species of unwanted woody plants as well as annual and perennial broadleaf weeds.

Caution Application under drought conditions may provide less than desirable results. Use low spray pressures to minimize spray drift. Avoid contacting nearby susceptible crops or other desirable plants. Avoid contaminating water for irrigation or domestic use. Do not use or store near heat or open flame.

Site of action (both) Group 4: synthetic auxin

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

Chemical family Pyridine

triclopyr choline (Vastlan)

Rate 1 to 2 quarts/a product

Time Apply when woody plants and broadleaf weeds are actively growing.

Remarks Adjust rate for type of vegetation to be controlled. Controls both emerged herbaceous and woody broadleaf plants. To control biennial thistles or other biennial species, apply before flower stalks appear. Add an approved nonionic surfactant to the spray mix and use at least a spray volume of 10 gal/a.

Caution Do not allow drift to desirable vegetation. Do not apply more than 2 quarts/a Vastlan in a growing season. Many forbs (desirable broadleaf plants) can be seriously injured or killed.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

2,4-D (several products)

Rate 1 to 4 lb ae/a

Time Apply when annual weeds are young and growing vigorously. Apply when perennial weeds are growing rapidly-generally, near the bud stage. Repeated applications may be necessary.

Remarks Controls many annual, biennial, and perennial broadleaf weeds.

Caution Do not apply when conditions favors drift from treated areas. Do not contaminate water for irrigation or domestic use.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid