Pasture Herbicides:Control, Use, and Costs

Brie MenjouletAgronomy Specialist

MU Extension‐ Hickory County

How Herbicides Work

• Herbicides must disrupt one or more vital plant processes in order to kill the plant

*Amino Acid Synthesis*

*Protein Synthesis**Lipid Synthesis* *Pigment Synthesis*

*Nucleic Acid Synthesis*

*Photosynthesis*

*Energy Transfer*

*Growth*

*Cell Division (mitosis & meiosis)*

*Transpiration & Respiration*

*Uptake & Translocation of Ions & Molecules*

Quick Review• Plant anatomy:

Xylem‐ vascular tissue that transports water and minerals upward from rootsPhloem‐ transports sugars made in leaves downward to roots & other plant cells Chloroplast‐ plant cell component where photosynthesis occurs and contains the chlorophyll that gives plants their green color

Methods of Application1. Foliar Applied Herbicides:

A. Translocated:• Observation of results is slower• Movement of chemicals occur within the plant• Most broadleaf pasture herbicides fit here

B. Contact: • Results observed quickly• Leaf cells are destroyed• More water use required• Used more often with row crop production

2. Soil Applied Herbicides:Uptake of herbicides occurs in root (little to no foliar activity)Primarily applied preplant incorporated & preemergence in row crop & alfalfa

Adjuvants• Are any substance in or added to a herbicide that improves herbicide activity, performance, or application characteristics

Special Purpose & ActivatorCompatibility, buffering, antifoam, and drift control agentsCan increase absorption and rainfastnessDecrease photodegradationIncludes surfactants, emulsifiers, diesel fuel, and keroseneEmulsifiers help diesel mix with water

Herbicides

• Restricted vs. Non‐restricted

Toxicity & risk to water

• Non‐selective vs. Selective

Selective = 2,4‐DNon‐Selective = Glyphosate (Roundup)

Herbicide Ladder

• Groups are numerical and are categorized by the mode or site of action that kills the plant

• Families kill the plant in the same method but use different chemical formulations

• Many pasture herbicides = Group 4 HerbicidesGrowth RegulatorsPhenoxy‐acetic acids (2,4‐D), benzoic acids (Banvel), and the pyridines (Tordon, Grazon)

GroupFamily

Trade Name

Common Name

Group 4Pyridine Acid

Remedy

Triclopyr

=

Common Pasture Herbicides

• 2,4‐DEster vs. AmineAmine is less volatile but can be less effective

• Picloram ≈ Tordon• Triclopyr ≈ Remedy & Garlon 4• Dicamba ≈ Banvel & Clarity• Aminopyralid ≈Milestone• Metsulfuron ≈ Cimarron & Escort

Combining Chemicals• Increases the spectrum of weed controlled

2,4‐D

+ picloram = Grazon P+D+ triclopyr = Crossbow+ dicamba = WeedMaster & Range Star+ Aminopyralid = GrazonNext

• 2,4‐D can be added to many products that are not already pre‐mixed

• Check the active ingredients and label instructions before adding 2,4‐D

Good General Purpose Brush Spray

0.25% Remedy

+

1% Grazon P+D+

0.25% Nonionic Surfactant

Herbicide

Grazing and Haying Restrictions Following Application

(Days)

Interval Between Application and

PlantingBeef Lactating Dairy Removal of

meat animals before slaughter

Forage Grasses

Alfalfa / CloversGrazing Haying Grazing Haying

2,4-D amine or ester 0 0 7 30 3 NGS NGSBanvel / Clarity

up to 1 pt / acup to 2 pt / acup to 4 pt / ac

000

000

72140

375170

303030

see label see label

(0.1-0.2 oz) 0 0 0 0 0 fescue18 mo. 12 mo.Max (Rate 1) 0 0 7 37 30 fescue18 mo. 12 mo.Crossbow none 14 <2 gal - 14 next

season21 days NGS

ForeFront R&P - 7 - 7 - - FBGlyphosate*

renovationspot application

5614

5614

5614

5614

00

anytimeanytime

anytimeanytime

Grazon P + D 0 30 7 30 3 FB FBTordon 22K 0>1 qt. - 14 14 14 3 FB 36 mo.Milestone 0 0 0 0 - - FBPasturegard 0 14 next season 14 3 120 days 1 mo.Remedy Ultra 0 14 next season 14 3 - -Spike (spot treatment) 0 1 year 0 1 year 0 > 2 years

FB> 2 years

FBSurmount 0 7 14 14 3 1 year FBWeedmaster 0 37 7 37 30 see label see label

New Herbicide: Chaparral™• New prepackaged herbicide mixture for pastures from 

Dow (2009 release in MO)• 62% wettable granular formulation: 85% 

aminopyralid & 15% metsulfuron• Rates of 2.0 to 3.3 oz product/acre:

2.0 oz/ac = 4.2 fl oz/ac Milestone + 0.3 oz/ac Cimarron2.5 oz/ac = 5.3 fl oz/ac Milestone + 0.38 oz/ac Cimarron3.3 oz/ac = 7.0 fl oz/ac Milestone + 0.5 oz/ac Cimarron 

• No haying or grazing restrictions• Key weeds controlled: Canada thistle, common 

mullein, goldenrod, horsenettle, musk thistle, poison hemlock, ragweeds, & wild carrot

• Higher rates can cause significant fescue seedhead and yield reduction, especially when applied in spring

Influence of Metsulfuron‐based Products and Application Timings on Early Summer Forage Yield (Columbia, 2009)

Influence of Metsulfuron‐based Products and Application Timings on Fescue Seedhead Reduction (Columbia, 2009)

2.5 ozs ChaparralEarly Spring Application

Rate 1 Cimarron MaxEarly Spring Application

UntreatedEarly Spring Application

pictures taken 30 days after early spring application

Influence of Metsulfuron‐based Products & Application Timings on Fescue Yield & Seedhead Reduction

Missouri Weed Survey

Musk ThistleBull Thistle

Horsenettle / Bull NettleIronweed

Multiflora RoseSericea Lespedeza

RagweedBuckbrush

Application Timing• Summer Annuals: Young & actively growing (usually spring)

Common CockleburBitter sneezeweedSmartweedPerilla MintRedroot PigweedJimsonweedLambsquarterRagweed

Photo by Marisa Williams

Application Timing

• Winter Annuals: Young & actively growing (fall or early spring)

HenbitHorseweedDeadnettleChickweedVirginia PepperweedShepherdspurse

Application Timing• Biennials: Rosette stage (fall or early spring)

Common BurdockWild CarrotCommon MulleinThistlesPoison HemlockSpotted Knapweed

Application Timing

• Perennials: Pre‐bloom to bloom stageCurly DockGoldenrodStinging NettleChicoryCommon PokeweedCommon MilkweedPassion FlowerTrumpetcreeper

Investigations Into the Control of Dewberry in Missouri

ApplicationTiming

Dewberry Control Across All Herbicide

Treatments--- # Stems/Plot 1 YAT ---

Full Bloom 76Fall 27

Influence of Herbicides & Application Timings on Dewberry Control 1 Year After Treatment (Salem, MO 2009)

Dewberry Control

Treatment RateFull Bloom Application

Fall Application (October)

‐‐‐product/A‐‐‐ ‐‐# Stems/Plot 1 Year After Trtmt‐‐

Pasturegard 4 pts 73 24

Surmount 4 pts 49 32

Remedy Ultra 2 pts 63 26

Grazon P+DRemedy Ultra

2 pts1 pt

61 42

Cimarron 0.4 oz 89 16

Cimarron Max Rate 1 83 20

Cimarron Max Rate 2 85 13

Chaparral 2 ozs 90 24

Chaparral2,4‐D Ester

2 ozs1 qt

64 22

Chaparral 3 ozs 79 19

Forefront R&P 2 2/3 pts 82 61

Remedy Ultra2,4‐D Ester

1 pt1 qt

84 37

DPX‐MAT28 1 oz 90 14

Untreated ‐‐‐‐ 96 81

LSD(0.05) within timings (Columns): 24

LSD(0.05) across timings (Rows): 27

Untreated 0.4 ozs Cimarron/Acre 0.4 ozs Cimarron/AcreFull Bloom Application Timing Fall Application Timing

96 Stems/Plot 89 Stems/Plot 16 Stems/Plot

Influence of Herbicides & Application Timings on Dewberry Control 1 Year After Treatment (Salem, MO 2009)

Untreated 3 ozs Chapparal/Acre 3 ozs Chapparal/AcreFull Bloom Application Timing Fall Application Timing

96 Stems/Plot 79 Stems/Plot 19 Stems/Plot

Influence of Herbicides & Application Timings on Dewberry Control 1 Year After Treatment (Salem, MO 2009)

Untreated 4 pts Pasturegard/Acre 4 pts Pasturegard/AcreFull Bloom Application Timing Fall Application Timing

96 Stems/Plot 73 Stems/Plot 24 Stems/Plot

Influence of Herbicides & Application Timings on Dewberry Control 1 Year After Treatment (Salem, MO 2009)

Herbicide Price Size “Standard” Rate/Acre Cost per Acre

2,4‐D Amine 4 41.75 2.5 gal 2 pt 4.18Banvel 155.00 2.5 gal 2 pt 15.50Crossbow 66.54 1 gal 4 pt 33.27Garlon 4 269.00 2.5 gal 2 pt 26.90Remedy Ultra 105.00 1 gal 2 pt 26.25PastureGard 159.95 2.5 gal 2 pt 16.00GrazonNext 87.50 2.5 gal 2 pt 8.75Milestone 94.10 1 qt 4 fl oz 11.76Cimarron  149.00 10 oz 2 oz 29.80Chaparral 112.95 1.25 lb 2 oz 11.30Tordon 22K* 86.95 1 gal 1 pt 10.87HiredHand P+D* 67.95 2.5 gal 2 pt 6.80Grazon P+D* 81.73 2.5 gal 2 pt 8.17Surmount* 154.63 2.5 gal 2 pt 15.46

If using an surfactant‐ add about $1.40 per acre

Selecting the Right Herbicide

• IDENTIFY THE WEEDS• What stage of growth are they in?• Is a mixture of different herbicides needed for broad spectrum control?

• Are legumes present? Planning to overseed?• Read the herbicide label & follow directions• Do you have appropriate protective wear?

Signal Words

• Toxicity (short‐term)          Signal WordsHarmful effects from oral or dermal contact,  inhalation, &  eye exposure“POISON” = will be printed on label in red“CAUTION” = slightly toxic “WARNING” = moderately toxic“DANGER” = highly toxic

• Use protective wear recommended by label!

Selecting the Right Herbicide

• IDENTIFY THE WEEDS• What stage of growth are they in?• Is a mixture of different herbicides needed for broad spectrum control?

• Are legumes present? Planning to overseed?• Read the herbicide label & follow directions• Do you have appropriate protective wear?• How much chemical will you need? Call your supplier for local inventory

• Check the weather forecast

Other Control Methods & Considerations

• Are the weeds hurting forage quality of hay or reducing grazing potential

• Pasture and Hay Fields:FertilityGrass vigor & competitionGrazing & haying techniques

• Mechanical Control:Will brush hogging gain any control?

• Biological Control:Weevils, borers, & other insectsGoats

Questions?

Sericea Lespedeza

• Apply when sericea is 12” or taller

• Or, from bud to flowering

RemedyCimarron

Pasturegard

Poison Hemlock

Tordon

Grazon

Blackberry

(flowering) Remedy 

Pasturegard Surmount

(post‐flowering) Cimarron

(second‐year growth)

Multiflora Rose

Grazon

Tordon

PastureGard

Remedy

Spike pellets

(full bloom)

Cedar

Fire

Chain Saw

Tordon 22K on <4 ft cedars

Locust

GrazonSurmount

Ironweed

Grazon

Tordon

Surmount

Remedy

PastureGard

Horsenettle

Grazon

Tordon

Milestone

Oak

Remedy

Sumac

2,4‐D early

Remedy

Crossbow

Osage Orange

Remedy

Cut stump treatment Tordon 

RTU

Basal bark treatment of Pathfinder II

Broomsedge

Lime

Phosphorus

Glyphosate through a wiper

Little Bluestem

Broomsedge

Perilla Mint

2,4‐D

Grazon

Remedy

Prickly Pear Cactus

Surmount

Tordon

Grazon

Burdock

2,4‐D + Banvel

Grazon

Tordon

Johnsongrass

Glyphosate

“2,4‐D Weeds”

Pigweeds

Common & Giant Ragweeds

Woolly Croton

Bitter Sneezeweed

Plaintains

Common Ragweed

2,4‐D

Grazon

Spiny Pigweed

2,4‐D early

Grazon

Buckbrush

2,4‐D early

Grazon

Marijuana

Call Sheriff ’s Department