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Publication #SS-AGR-229

Weed Management in Alfalfa1

J. A. Ferrell and B. A. Sellers2

Tables

Table 1. 

Weed Management in Alfalfa.

Trade Name and Broadcast Rate/Acre of Commercial Product

Common Name

Remarks

Preplant Incorporated (PPI)

Balan 60DF

2 lb

benefin

Incorporate 2–3 inches deep before planting for grass control. EPTC may provide better broad spectrum weed control. Some epinastic injury to alfalfa usually occurs from EPTC, however, injury is normally temporary. Do not use if grain or grass crop is to be planted with alfalfa. Research has shown significant injury as stand reduction from Balan. Injury would be expected to be less when used on fall than on spring planted alfalfa. The yield of the first cutting may be reduced when treated with Balan.

Eptam

3.5 pt

EPTC

Postemergence—Seedling Alfalfa (First Season)

Butyrac 200

or

Butoxone

(1.75 lb gal)

2 to 3 qts

2,4-DB

Apply in fall or spring after alfalfa has two to four trifoliate leaves. Controls emerged annual broadleaf weeds less than 3 inches tall. Do not graze or cut for hay for 60 days after application. Rainfall or irrigation within 7 to 10 days after treatment may cause injury. DO NOT add wetting agents or surfactants to the spray solution.

Buctril 2L

1.5 pt

bromoxynil

Apply to seedling alfalfa that has a minimum of four trifoliolate leaves. Spray winter annual broadleaf weeds that do not exceed the 4-leaf stage or 2 inches in height, or have rosettes greater than 1.5 inches in diameter. DO NOT apply when temperatures exceed 70°F or unacceptable crop injury may occur. DO NOT add a surfactant or crop oil. DO NOT cut for feed or graze spring treated alfalfa for 30 days after application. DO NOT cut for feed or graze fall or winter treated alfalfa for 60 days after application.

Pursuit 70DG

1.08 to 2.16 oz.

imazethapyr

Apply to seedling alfalfa with a minimum of two trifoliate leaves and when weeds are 1 to 3 inches tall or before rosette forming weeds exceed 3 inches in diameter. Pursuit requires a 1-hour rain free period. Pursuit may cause a temporary reduction in height or slight leaf yellowing. DO NOT feed, graze, or harvest alfalfa for 30 days after application. A maximum total of 2.16 oz./A of Pursuit may be applied per year. Add a nonionic surfactant at 0.25% v/v or a crop oil concentrate at 1.5 to 2.0 pts/A to the spray solution. If replanting is necessary in a field treated with Pursuit, do not plant alfalfa for 4 months following the application of Pursuit. Do not apply more than 1.44 oz. during the last year of the stand.

Raptor

4 to 6 fl oz.

imazamox

Apply after the 2nd trifoliate stage, or larger, when weeds are 3" in height or less. There may be temporary reduction in growth, but alfalfa will quickly recover. Add a nonionic surfactant at 0.25% v/v or a crop oil concentrate at 1% v/v to the spray solution. DO NOT harvest alfalfa hay for 20 days, or graze for 70 days, after application. A maximum total of 6 fl. oz./A of Raptor may be applied per year.

Kerb 50W

1 to 1.5 lb

pronamid

Spray preemergence or early postemergence for control of winter annual weeds after the alfalfa has reached the trifoliolate leaf stage. Do not graze or cut for hay for 120 days after treatment.

Poast (1.5 lb gal)

1 to 2.5 pt

or

Poast Plus (1 lb gal)

1.5 to 2.25 pt

sethoxydim

Apply 1 pt. of Poast or 1.5 pts. of Poast Plus with 2 pts. of crop oil concentrate/A for control of annual grasses up to 8 inches tall (varies with species). Use 2 ½ pts./A of Poast or 2.25 pts./A of Poast Plus if rhizome johnsongrass is to be controlled, followed by a second application to regrowth or new plants. Do not apply to grass or alfalfa under stress. Apply before the grass has been cut. Do not apply Poast or Poast Plus within 7 days of feeding, grazing or harvesting undried forage, or within 14 days of cutting for dry hay.

Select Max

9–32 oz/A

or

Select 2EC, Arrow, others

6 to 16 oz/A

clethodim

Apply with a crop oil concentrate at 1% v/v for the control of most annual grasses up to 6 to 8 inches tall. Select Max can be applied with either crop oil or non-ionic surfactant. Also, has good activity on johnsongrass and suppresses common bermudagrass. DO NOT apply within 15 days of grazing, feeding, or harvesting alfalfa for forage or hay. May be tank-mixed with 2,4-DB; however, the risk of temporary injury to alfalfa will increase.

Postemergence—1st year planting (Between Cuttings)

Raptor

4 to 6 fl oz.

imazamox

Apply when weeds are 3" in height or less. See above for additional surfactant and grazing information.

Gramoxone Inteon

1 pt

paraquat

Apply to small emerged annual grass and broadleaf weeds in first year alfalfa immediately after removing hay between cuttings. Do not treat more than 5 days after cutting. Add a nonionic surfactant at 1 pt./100 gals. of water. Do not make more than two applications during the growing season. Apply in 20–40 gals. of water/A. Weeds much beyond the seedling stage and stubble of those cut off during harvest will be less affected by the treatment. Do not graze, cut or harvest within 30 days of application.

Postemergence—Established Dormant Alfalfa (greater than 1 year old)

Sencor 4L

12 fl oz

Sencor 75DF

or

Lexone 75DF

8 oz

metribuzin

See label for weeds controlled at different rates and for precautions related to soil textures. Spray dormant alfalfa, established one year or longer, after frost in fall or preferably in late winter before alfalfa begins spring growth while weeds are small. Provides preemergence and early postemergence weed control when surfactant is added. Do not use these treatments on alfalfa-grass mixtures. Do not use Sencor, Lexone or Velpar on sands. The higher rate of Velpar may cause crop damage. Do not graze or cut for hay within 28 days after Sencor or Lexone treatment. Do not graze or cut for hay within 30 days after Velpar treatment. Do not tank-mix any of these herbicides.

Velpar 2L

2 to 3 pt

or

Velpar 90SP

8 to 12 oz

hexazinone

Kerb 50W

1 to 1.5 lb

pronamide

Apply in January at lower rate for most annual winter grasses, except higher rate for annual ryegrass or orchardgrass. Do not graze or cut for hay for 120 days after treatment. Provides preemergence and early postemergence control. Do not tank mix with other herbicides.

Raptor

4 to 6 fl oz.

imazamox

Apply when weeds are 3" in height or less. See above for additional surfactant and grazing information.

Gramoxone Inteon

1- 2 pt/A

paraquat

Apply during the winter months when established alfalfa is dormant. DO NOT apply dormant treatments to seedling alfalfa less than 6 months old. Controls Italian ryegrass (less than 6 in. tall), chickweed and most other winter annual weeds. Green alfalfa foliage present at time of application will become necrotic (brown). DO NOT apply after the initiation of new spring growth. Add a nonionic surfactant at 1.0 pt./100 gals. of spray solution. DO NOT graze or harvest within 60 days of application. Make only one application per season.

Preemergence—Established Alfalfa

Solicam (80 DG)

1.25 to 2.5 lb

norflurazon

Apply to established alfalfa in spring or early fall for the control of annual grasses and annual broadleaf weeds such as tropic croton and prickly sida. May be applied to dormant and actively-growing alfalfa. Apply to actively-growing alfalfa following hay removal to ensure spray penetration to the soil surface. DO NOT apply to seedling alfalfa earlier than 5 months after emergence. DO NOT apply Solicam within 28 days of harvest. Use the low rate on sandy soils. Zorial Rapid 80 may be tank-mized with Gramoxone Extra, Poast, Kerb, Sencor, Lexone and 2,4-DB. For 16 months following application rotate only to cotton, soybeans or peanuts.

Postemergence—Established Alfalfa

Butyrac 200

or

Butoxone

2 to 3 qts

2,4-DB

Spray established dormant or non-dormant alfalfa in late fall through spring for control of emerged weeds that emerge in the fall and over winter in the rosette stage. Do not graze or cut for hay within 30 days after treatment. Overhead irrigation or rainfall within a few days after use may wash chemical into the root zone possibly causing some twisting of stems and malformation of leaves. Do not add wetting agents or surfactants to the spray mix.

Pursuit 70DG

1.08 to 2.16 oz

imazethapyr

Apply to established alfalfa in the fall, or in the spring to dormant or semi-dormant alfalfa. Spring treatments should be made before excessive alfalfa growth (less than 3 inches of new growth) to reduce spray interference. Apply when weeds are 1 to 3 inches tall or before rosette forming weeds exceed 3 inches in diameter. DO NOT feed, graze, or harvest alfalfa for 30 days after application. A maximum total of 2.16 oz./A of Pursuit may be applied per year. Add a nonionic surfactant at 0.25% v/v or a crop oil concentrate at 1.5 to 2.0 pts/A to the spray solution. If replanting is necessary in a field treated with Pursuit, do not plant alfalfa for 4 months following the application of Pursuit. Do not apply more than 1.44 oz. during the last year of the stand.

Raptor

4 to 6 fl oz.

imazamox

Apply when weeds are 3" in height or less. See above for additional surfactant and grazing information.

Poast (1.5 lb gal)

1 to 2.5 pt

or

Poast Plus (1 lb gal)

1.5 to 2.25 pt

sethoxydim

Apply 1 pt. of Poast or 1.5 pts. of Poast Plus with 2 pts. of crop oil concentrate/A for control of annual grasses up to 8 inches tall (varies with species). Use 2 ½ pts./A of Poast or 2.25 pts./A of Poast Plus if rhizome johnsongrass is to be controlled, followed by a second application to regrowth or new plants. Do not apply to grass or alfalfa under stress. Apply before the grass has been cut. Do not apply Poast or Poast Plus within 7 days of feeding, grazing or harvesting undried forage, or within 14 days of cutting for dry hay.

Select 2EC

or

Arrow

6 to 8 fl oz.

clethodim

Apply with a crop oil concentrate at 1% v/v for the control of most annual grasses up to 6 to 8 inches tall. Also, has good activity on johnsongrass and suppresses common bermudagrass. DO NOT apply within 15 days of grazing, feeding, or harvesting alfalfa for forage or hay. May be tank-mixed with 2,4-DB; however, the risk of temporary injury to alfalfa will increase.

Postemergence—Established Alfalfa (Between Cuttings)

Pursuit 70DG

1.08 to 2.16 oz

imazethapyr

Apply as a between cut treatment. Remove hay from the field and apply before excessive alfalfa regrowth. Apply when weeds are 1 to 3 inches tall or before rosette forming weeds exceed 3 inches in diameter.DO NOT feed, graze, or harvest alfalfa for 30 days after application. A maximum total of 2.16 oz./A of Pursuit may be applied per year. Add a nonionic surfactant at 0.25% v/v or a crop oil concentrate at 1.5 to 2.0 pts/A to the spray solution. If replanting is necessary in a field treated with Pursuit, do not plant alfalfa for 4 months following the application of Pursuit. Do not apply more than 1.44 oz. during the last year of the stand.

Raptor

4 to 6 fl oz.

imazamox

Apply when weeds are 3" in height or less. See above for additional surfactant and grazing information.

Gramoxone Inteon

1 pt/A

paraquat

Apply to established stands (at least one year old) immediately after alfalfa has been removed for silage or hay. Do not treat more than 5 days after cutting. Add surfactant at 1 pt./100 gals. of spray mix. DO NOT graze, cut or harvest within 30 days of application. Make 1 to 3 applications as needed during the cutting season. Apply in 20 to 40 gals. of water/A. Weeds much beyond the seedling stage and stubble of those cut off during harvest will be less affected by the treatment.

Table 2. 

Estimated effectiveness of recommended herbicides on common weeds in Florida Alfalfa.

Time of Application

PPI

PPI

PRE

POT

POT

Balan

EPTC – Eptam

Kerb

Poast or Select

Pursuit or Raptor

bahiagrass

P

P

P

F

--

bermuda grass

P

P

P

F–G

P

bitter sneezeweed

P

P

P

P

--

blackberry

P

P

P

P

--

bracken fern

P

P

P

P

--

briars (Smilax)

P

P

P

P

--

broomsedge

P

P

P

P

--

bulrush

P

P

P

P

--

buttercup

P

P

P

P

--

chickweed

F

E

G

P

E

crabgrass

E

G

F

G–E

F

cudweed

P

P

P

P

--

curly dock

P

P

P

P

F

dallisgrass

P

P

P

P

--

dandelion

P

G

P

P

--

dodder

P

P

E

P

--

dogfennel

P

P

P

P

--

evening primrose

F

F–G

P

P

--

foxtails

G

G

P

E

G

gallberry

P

P

P

P

--

goldenrod

P

P

P

P

--

henbit

F

G

P

P

E

honeysuckle

P

P

P

P

--

horsenettle

P

P

P

P

--

horseweed

P

P

P

P

--

Italian ryegrass

G

E

G

E

P

johnson grass

P

P

P

G

P

kudzu

P

P

P

P

--

little barley

G

G

E

F

--

mayweed

--

--

P

P

--

nettle, stinging

P

P

P

P

--

nutsedge

P

F

P

P

F

palmetto

P

P

P

P

--

perilla mint

P

P

--

P

--

persimmon

P

P

P

P

--

pigweed species

G

G

--

P

G

pokeberry

P

P

P

P

--

prickly pear

P

P

P

P

--

ragweed

P

P

P

P

F

red sorrel

P

P

P

P

--

sandbur

E

G

P

G

--

shepherds- purse

P

G

G

P

E

sicklepod

P

F

P

P

--

smutgrass

P

P

P

P

--

swinecress

P

G

F

P

--

Texas panicum

G–E

G

P

E

--

thistles

P

E

P

P

P

tropical soda apple

P

P

P

P

--

vaseygrass

P

P

P

P

--

Virginia pepperweed

P

G

P

P

--

wax myrtle

P

P

P

P

--

wild cherry

P

P

P

P

--

wild garlic

P

P

P

P

--

wild radish

P

P-F

P

P

G-E

wild plum

P

P

P

P

--

wild rose

P

P

P

P

--

wooly croton

P

P

P

P

P

Estimated effectiveness based on rates recommended in this report. Effectiveness may vary depending on factors such as herbicide rate, size of weeds, time of application, soil type, and weather conditions.

Weed Control Symbols: E = 90-100% control; G = 80-90% control; F = 60-80% control; P = less than 60% control.

Time of Application Symbols: PPI = preplant incorporated; PRE = preemergence; POT = postemergence over the top; -- = insufficient observations.

Table 3. 

Estimated effectiveness of recommended herbicides on common weeds in Florida Alfalfa (continued).

Time of Application

POT

POT

POT

POT

POT

POT

 

Velpar

Sencor or Lexone

Paraquat

Buctril

2,4-D

2,4-DB

bahiagrass

P

P

P

P

P

P

bermuda grass

P

P

P

P

P

P

bitter sneezeweed

--

--

--

--

E

G

blackberry

F

P

P

P

F

P

bracken fern

F

--

P

--

P

P

briars (Smilax)

F

P

P

P

P

P

broomsedge

P

P

P

P

P

P

bulrush

--

--

P

P

G

P

buttercup

G

G

G

--

E

F

chickweed

E

E

E

F

F

P

crabgrass

P

F

F

P

P–F

P

cudweed

--

--

G

P

F

--

curly dock

P

--

P

--

F

P

dallisgrass

--

P

P

P

P

P

dandelion

E

G

G

P

E

G

dodder

--

--

G–E

--

P

P

dogfennel

--

--

P

P

F

P

evening primrose

E

G

P–F

--

E

G

foxtails

--

P

F

P

P

P

gallberry

P

P

P

P

G

P

goldenrod

--

--

P

P

F

P

henbit

E

E

G

F

F

P

honeysuckle

--

P

P

P

E

P

horsenettle

--

P

P

P

P

P

horseweed

--

P

P

P

F

P

Italian ryegrass

G

P

G–E

P

P

P

johnson grass

--

P

P

P

P

P

kudzu

--

P

P

P

P–F

P

little barley

E

P

G–E

P

P

P

mayweed

F–G

--

E

--

F

P

nettle, stinging

--

--

--

--

P

P

nutsedge

P

P

P

P

P

P

palmetto

P

P

P

P

P

P

perilla mint

--

--

--

--

P

--

persimmon

F

P

P

P

P

P

pigweed

G

G

G

F

F

G

pokeberry

--

--

--

P

E

G

prickly pear

P

P

P

P

P

P

ragweed

F

G

G

F

E

G

red sorrel

--

--

P–F

--

P

P

sandbur

--

F

G

P

P

P

shepherds-

purse

E

E

G

G

E

G

sicklepod

--

F

F–G

--

G

F

smutgrass

G

P

P

P

P

P

swinecress

E

E

E

E

E

F

Texas panicum

--

P–F

G

P

P

P

thistles

E

G

G

P

E

F

tropical soda apple

G

P

P

P

P–F

P

vaseygrass

--

P

P

P

P

P

Virginia pepperweed

E

G

G

G

G

E

wax myrtle

P

P

P

P

G

P

wild cherry

E

P

P

P

E

P

wild garlic

--

P

E

P

G–E

P

wild radish

E

E

P

F–G

G

P

wild plum

E

P

P

P

E

P

wild rose

--

P

P

P

G

P

wooly croton

P

P

P

P

G

P

Estimated effectiveness based on rates recommended in this report. Effectiveness may vary depending on factors such as herbicide rate, size of weeds, time of application, soil type, and weather conditions.

Weed Control Symbols: E = 90-100% control; G = 80-90% control; F = 60-80% control; P = less than 60% control.

Time of Application Symbols: POT = Postemergence over the top.

Footnotes

1.

This document is SS-AGR-229, one of a series of the Agronomy Department, UF/IFAS Extension. Original publication date January 2005. Revised October 2008. Reviewed October 2015. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

J. A. Ferrell, professor, Agronomy Department; and B. A. Sellers, assistant professor, Agronomy Department, Range Cattle Research and Education Center; UF/IFAS Extension, Gainesville, FL 32611.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. Use herbicides safely. Read and follow directions on the manufacturer's label.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.