Forage Weed Control Update

1
Weed Management in Pastures - 2007
Dr. Tim Murphy, Extension Weed Specialist The
University of Georgia used with
permission Georgia Agricultural Education
Curriculum Office June 2007
2
Pasture Weed Issues

• Lack of management - fertility, lime, mowing,
  overgrazing
• Only 15 of Georgia pastures are sprayed on
  annual basis
• Grazing restrictions
• Legume tolerance

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Do I spray or fertilize first?

• Spray first
• Control existing weeds
• Begin soil-test based lime and fertilizer program
• Establish legumes after good weed control has
  been practiced for 1 to 2 years

4
Forage Response to Weed Control and Fertilizer
(TAMU Wet Year)
1991. Bade, TAES
5
Fertility Examples for the Southeast

• Broomsedge
• General indicator of low pH (K
• Affected by grazing
• Sericea lespedeza
• Extremely tolerant of low pH,
• P and K
• Bahiagrass and Common Bermudagrass
• More tolerant of low K than hybrid bermudagrass
• Also more tolerant of close grazing

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Effect of Grazing on Weed Control

• Grazing is SELECTIVE defoliation
• Unlike mowing this may allow greater pressure to
  be placed on a single forage species
• Shift competitive advantage toward favorable
  species
• Can alter selectivity with animal species,
  stocking rate and timing

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Vegetation Preferences
S. Forages 3rd Ed.
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Overgrazing

• Overgrazing decreases root CHO of forage species,
  compacts soil, injures crowns, and decreases
  rooting depth.
• Releases unpalatable species like horsenettle
• Ideally want to maintain a minimum forage height
• Leaf area maintained - photosynthesis
• Improves vigor and competitive advantage for
  desired species
• Shades weed seedlings
• 2-3 for bermudagrass in summer months
• 3-4 for tall fescue
• Heavily grazed hybrid bermudagrass can encourage
  common and bahiagrass encroachment

9
Under grazing can also be a factor

• Weeds can outgrow and shade forage species

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Do we really want to eliminate all weeds from
pastures?
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(No Transcript)
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Positive Attributes of Weeds in Pastures

• Can dilute toxins in tall fescue during critical
  times
• Chickweed, crabgrass, dallisgrass, lespedeza
• Can extend grazing season and improve
  productivity
• Crabgrass in tall fescue
• Can improve quality
• Crabgrass

Chickweed, curly dock, shepherds purse and tall
fescue mixture. Eatonton GA
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DOES MOWING HELP?
14
Mowing

• Less effective than grazing
• Largely cosmetic
• Keeps forage in vegetative/competitive stage
• Possible to decrease some annual weeds IF
• mowed before viable seed formation
• Some perennials are not affected by mowing
• Horsenettle
• Timing is important
• Dogfennel, thistle?

15
When do you spray?

• Winter annuals - henbit, chickweed, buttercups,
  thistles
• November through March
• Summer annuals - spiny amaranth, bitter
  sneezeweed
• April through mid-July
• Perennials
• growth stage dependent

16
Herbicide Options

• 2,4-D
• dicamba (Vanquish, Banvel)
• 2,4-D dicamba (WeedMaster, others)
• dicamba diflufenzopyr (Overdrive)
• triclopyr (Remedy)
• 2,4-D triclopyr (CrossBow)
• triclopyr clopyralid (Redeem)
• 2,4-D picloram (Grazon PD, GunSlinger)
• fluroxypyr picloram (Surmount)
• fluroxypyr triclopyr (PastureGard)

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Herbicide Options (cont.)

• aminopyralid (Milestone)
• aminopyralid 2,4-D (ForeFront)
• diuron (Direx, Diuron)
• metsulfuron (Cimarron)
• metsulfuron chlorsulfuron (Cimarron Plus)
• metsulfuron 2,4-D dicamba (Cimarron MAX)
• hexazinone (Velpar)
• sulfosulfuron (Maverick) Section 18 2006
• tebuthiuron (Spike)
• paraquat (Gramoxone Extra)
• glyphosate (Roundup UltraMax)
• imazapic (Plateau) (no longer an option)

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Remedy

• 4.0 lbs./gal. triclopyr ester
• low volatility
• Excellent on upright blackberry, numerous
  broadleaf weeds
• Good on tropical soda apple
• Fair on horsenettle
• Poor on pokeweed, honeysuckle, trumpetcreeper

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Remedy

• Mixes with diesel, basal oils
• Remedy 20 80 diesel, excellent as basal
  application for trees control of pricklypear cactus and palmetto
• Injurious to clovers
• Apply to seedling grasses 5 to 6 inches tall or
  after tiller development

20
Remedy

• Grazing and haying restrictions
• Beef grazing - 0 d Dairy grazing - 14 d
• Hay - 7 d (all livestock types, except lactating
  dairy cattle, next growing season)
• Slaughter - 3 d

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Basal Stem Spray

• Stems should be less than 4 inches in diameter.
• More effective on trees with smooth bark.
• Can be done anytime. Easiest to do during the
  dormant season.

Mix 80 diesel fuel or vegetable oil 20
Remedy by volume.
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Basal Sprays
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Stump Treatment

• Treat as soon as possible after cutting.
• 80 diesel fuel 20 Remedy
• Remedy RTU is convenient, no mixing, low odor

24
Stump Treatment
Little stump, treat all
Big stump, treat perimeter
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Cimarron

• 60DF metsulfuron
• DuPont is phasing out Ally brand name for
  pastures
• Effective for Pensacola bahiagrass, spiny
  amaranth, curly dock, buttercup, wild garlic
  control, blackberry
• Poor horsenettle control
• Injurious to legumes ryegrass (4 mo plant back)

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Cimarron

• 0.1 to 0.3 oz. product per acre
• Use low rates on tall fescue and timothy
• Do not mix with liquid fert. for bahiagrass
  control
• 0 d grazing or haying restriction - all livestock

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Cimarron Plus

• Two-way product
• 48 metsulfuron 15 chlorsulfuron (63DF)
• Effective for Pensacola bahiagrass, spiny
  amaranth, curly dock, buttercup, wild garlic
  control, blackberry, dewberry, honeysuckle
• Poor horsenettle control
• Injurious to legumes ryegrass (4 mo plant back)

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Cimarron Plus

• 0.125 to 1.25 oz. product per acre
• Use
• Do not mix with liquid fert. for bahiagrass
  control
• 0 d grazing or haying restriction - all livestock

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Cimarron MAX

• Co-Pack product
• Metsulfuron 60DF 2,4-D amine (2.87 lbs./gal.)
  dicamba (1.0 lb./gal.)
• Increases number of broadleaf weeds controlled
• Use rates 0.25 oz./acre of Cimarron plus 1.0 to
  2.0 pts./acre of 2,4-D dicamba
• Add nonionic surfactant at 0.25 v/v

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Cimarron MAX

• Grazing Restrictions
• Lactating dairy animals 7 days
• Other livestock species 0 days
• Haying Restrictions
• All livestock 37 days

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Grazon PD, GunSlinger

• 2.0 lbs./gal. 2,4-D amine 0.54 lbs./gal.
  picloram amine
• Excellent control of broadleaf weeds
• Excellent on horsenettle and tropical soda apple
• For horsenettle, use 3 pts./acre at early bloom.
• About 30 d residual control
• Fair control of blackberry

32
Grazon PD, GunSlinger

• Injurious to clovers
• Apply to seedling grasses or overseeded small
  grains at tiller growth stage, 1.5 pts./acre or
  less
• Newly-sprigged bermuda 1.5 pts./acre, delay
  until stolons are 6 inches long
• Beef grazing - 0 d Dairy grazing - 7 d
• Hay - 30 d (all livestock types)
• Slaughter - 3 d

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Reseeding Restrictions Grazon PD

• Cool-season grasses - 21 days
• Clover - 2 pts./acre or less
• Fall-seeding permitted if Grazon PD applied no
  later than June (4 month plant back)
• Clover 2 to 3 pts./acre
• Spring (Feb. Mar.) seeding permitted the
  following spring for applications made no later
  than Sept. 15 the previous year.

34
Grazon PD GunSlinger - Good - BUT!!!!!

• Do not
• use hay from treated areas for compost or mulch
• transfer livestock to untreated areas without 7 d
  cleanout
• use manure for fertilizing broadleaf crops
• use in any temporary forage system involving
  broadleaf crops
• USE ONLY ON PERMANENT GRASS FORAGE SYSTEMS

35
Plateau

• BASF will no longer market to private landowners
• grass roadsides, wildflowers, noncropland sites
• WHY???
• Economics
• Low sales,objections to injury
• Can make more money in other markets

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Newly-sprigged Bermuda

• Direx 4L, Diuron 4L
• Karmex is not labeled for this use
• Plant sprigs 2 inches deep
• Apply immediately after sprigging
• Use 3.0 to 4.0 pts./acre
• Not labeled in established bermudagrass
• Annual grasses and broadleaf weeds
• 70 day grazing restriction

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Overdrive - BASF

• Dicamba diflufenzopyr
• Controls broadleaf weeds
• 0 day grazing or haying restriction
• Limited data base
• Primarily will be marketed for rights-of-way use

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Newest Herbicides

• PastureGard - fluroxypyr triclopyr (Remedy)
• controls annual, perennial, woody species
  enhanced control of blackberry
• Surmount fluroxypyr picloram
• controls annual, perennial, woody species
• Milestone aminopyralid
• ForeFront aminopyralid 2,4-D
• Maverick - sulfosulfuron

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PastureGard

• 1.5 lbs./gal. triclopyr ester 0.5 lbs./gal.
  fluroxypyr ester
• Controls numerous brush species and broadleaf
  weeds.
• Upright blackberry, sweet gums, Sericea
  lespedeza, dogfennel, gallberry, rose species,
  lantana
• Palmetto and yucca use 2.0 v/v solution in
  water
• Fair control of horsenettle and tropical soda
  apple
• Also has activity on maypop passionflower

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PastureGard

• Mixes with diesel and other oil carriers
• PastureGard 50 50 diesel, excellent as basal
  application for trees
• Injurious to clovers
• Apply to seedling grasses after tiller
  development

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PastureGard

• Beef and other livestock grazing - 0 d
• Dairy grazing not permitted during the growing
  season of application
• Hay 14 d (all livestock types)

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Reseeding Restrictions PastureGard

• Cool-season grasses and small grains - 21 days
• Clover and other legumes 30 days
• Other crops 120 days
• Labeled for use on permanent grass forage systems
• This includes permanent pastures that are
  overseeded with winter forages.

43
Surmount

• 1.19 lbs./gal. picloram amine 0.96 lbs. gal.
  fluroxypyr amine
• Controls broadleaf weeds, horsenettle, tropical
  soda apple, and pricklypear cactus.
• Apply 3 to 4.0 pts./acre for prickly pear cactus
  in fall months, control is very slow, about 2
  yrs.
• About 30 d residual control
• Excellent control of upright-growing blackberry
  (3 to 4 pts./acre)

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Surmount

• Injurious to clovers
• Apply to seedling grasses or overseeded small
  grains at tiller growth stage
• Newly-sprigged bermuda delay until stolons are 6
  inches long
• Beef grazing - 0 d slaughter 3 d
• Lactating Dairy Animals grazing 14 d silage 14
  d.
• Hay 7 d (all livestock types)

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Reseeding Restrictions Surmount

• Cool-season grasses - 21 days
• Clovers 12 months
• Other legumes 12 months

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Surmount- Its Good - BUT!!!!!

• Do not
• use hay from treated areas for compost or mulch
• transfer livestock to untreated areas without 7 d
  cleanout
• use manure for fertilizing broadleaf crops
• use in any temporary forage system involving
  broadleaf crops
• USE ONLY ON PERMANENT GRASS FORAGE SYSTEMS

47
Milestone

• 2.0 lbs./gal. aminopyralid
• Use rate 4.0 to 7.0 fl. ozs./acre
• Numerous broadleaf weeds thistles, horsenettle,
  buttercup
• Do not seed legumes year of application
  (additional research being conducted)
• Delay application until grasses have 4 to 5
  leaves.

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Milestone

• Non-volatile
• Injurious to legumes
• No grazing or hay restriction for any type of
  livestock
• Weak on sida species, dogfennel, plantains,
  blackberry, wild radish, other mustards.
• Add 2,4-D or Remedy for weeds above.

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ForeFront

• 0.33 lbs./gal. aminopyralid 2.67 lbs./gal 2,4-D
• Use rate 1.5 to 2.6 pts./acre
• Numerous broadleaf weeds thistles, horsenettle,
  buttercup, henbit, plantains, verbena
• Do not seed legumes year of application
  (additional research being conducted)
• Delay application until grasses have 4 to 5
  leaves.

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ForeFront

• Injurious to legumes
• No grazing restriction for any type of livestock.
• 7 day hay harvest restriction
• Better control of plantains and common pokeweed
  than Milestone

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Comparison of Grazon PD, Surmount, PastureGard,
Milestone and Forefront
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Comparison of Grazon PD, Surmount and
PastureGard, Milestone and ForeFront
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Maverick - Monsanto

• Sulfosulfuron, 75WDG
• Section 18 in GA, AL, MS, AR, OK, LA APPROVED FOR
  2007
• Controls johnsongrass and sedges in bermudagrass
  and bahiagrass
• Use rate 1.33 ozs./acre
• Add a nonionic surfactant at 0.25 v/v.

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Maverick - Monsanto

• Johnsongrass 18 to 24 inches tall, up to seedhead
  stage of growth
• Nutsedges 4 to 8 inches tall
• Does not control annual grasses, vaseygrass,
  dallisgrass, smutgrass, etc.
• Tank-mix with other herbicides for broadleaf weed
  control

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Maverick - Monsanto

• Grazing and haying restriction
• 14 days all livestock types
• Treated fields may be rotated only to wheat.
• Injurious to clovers.

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Winter Forages

• Annual ryegrass
• Wheat
• Oats
• Rye

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When do you spray?

• Winter annuals - henbit, chickweed, buttercups,
  thistles, wild radish (turnips)
• November through March
• Grass and Small Grain Forages
• Delay application until the 4 to 5 leaf growth
  stage

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Tolerance of 2- to 4-Leaf Wheat to Herbicides

• 2,4-D (1 and 2 pt. rates)
• Weedmaster (1, 2 and 4 pt. rates)
• Grazon PD (1, 2 and 4 pt. rates)
• Sprayed in mid-December
• 2- to 4-leaf wheat

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Effect of herbicides on seedling wheat injury
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Herbicide Options for Winter Grass Forages

• 2,4-D
• dicamba (Vanquish, Banvel)
• 2,4-D dicamba (WeedMaster)
• triclopyr (Remedy)
• 2,4-D picloram (Grazon PD, GunSlinger)
• fluroxypyr picloram (Surmount)
• fluroxypyr triclopyr (Pasturegard)
• aminopyralid (Milestone)

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2,4-D

• Amines and esters
• Delay application until grasses have 4 to 5
  leaves
• For grain production delay appl. until fully
  tillered
• Use up to 2.0 pts./acre, except on oats use 1.0
  pt./acre
• Weak on chickweed and henbit
• Good on buttercup, wild radish and other mustards

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2,4-D

• Grazing and haying restrictions varies by product
• Weedar 64
• Beef cattle 0 days
• Lactating dairy animals 7 days
• Hay all types 30 days

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WeedMaster

• 2.87 lbs. 2,4-D 1.0 lb. dicamba per gallon
• Delay application until grasses have 4 to 5
  leaves
• Use up to 2.0 pts./acre, except on oats use 1.0
  pt./acre
• Better than 2,4-D on chickweed and henbit
• Grazing restrictions only lactating dairy cows
  7 days
• Hay/silage 37 days, all livestock types

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Summary - Forage Weed Control

• Know cropping system
• Use approved cultural practices
• Identify weeds
• Select product
• Follow grazing and haying restrictions
• Proper application timing

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Summary

• Poor fertility and overgrazing are huge
  contributors to weed problems
• Long term solutions will have to address these
  issues
• Improving fertility and grazing management of
  mediocre stands may revive them
• Process likely slow vs herbicides
• Mowing can help