Fighting Weeds in Turf and Ornamentals

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Fighting Weeds in Turf and Ornamentals

• Barry J. Brecke
• Weed Scientist
• University of Florida

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Know Your Enemy
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Weed

• A plant growing where it is not wanted
• A plant out of place
• bermudagrass
• sports turf - great!
• Floratam sod production - no sale!
• Ornamental bed - no fun!

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Why worry about weed I.D.?

• The correct identification of weeds is the first
  step in the implementation of a successful weed
  control program.
• Weeds are often indicators of an underlying
  problem.

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Weed IdentificationWeeds as Indicators

• Indicator Weed(s)
• Red Sorrel
• Plantains
• Prostrate Spurge, Black Medic, Knotweed,
  Woodsorrel, Lespedeza, Bracted Plantain
• Sedges, Poa annua, Moss, Algae, Alligatorweed,
  Goosegrass

• Condition
• Low Soil pH
• High Soil pH
• Droughty Soils
• Wet Soils (overwatering)

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Weed IdentificationWeeds as Indicators

• Condition
• Sandy soil
• High Nematodes
• Low mowing ht.
• Compacted soil
• Low Soil N
• High Soil N

• Indicator Weed(s)
• Poorjoe, Sandspur
• Spurges, Pusley, Knotweed
• Algae, Poa annua, Chickweed
• Goosegrass, Poa annua, Knotweed,
• Legumes
• Poa annua, Chickweed, Moss

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Types of Weeds

• Broadleaf
• Net venation, opposite, alternate or whorled
  leaves, showy flowers.
• Grasses
• Parallel venation, alternate or 2-ranked leaves,
  rounded or flattened stems.
• Monocots (sedges, garlic)
• Parallel venation, 3-ranked leaves, triangular
  stems

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Annuals live one year and reproduce by seed.

• Summer Annuals
• Germinate in spring.
• Produce seeds in late summer or early fall.
• Die in fall.

• Winter Annuals
• Germinate fall through late winter.
• Flower and produce seed in late winter or early
  spring.
• Die in late spring or early summer.

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Biennials live two years.

• 1st year vegetative growth
• 2nd year flowers and dies.

Flower - reproductive stage
Musk thistle rosette - vegetative stage
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Perennials

• Live more than two years
• Reproduce by seeds, stolons, rhizome, corms,
  bulbs, tubers

garlic onion
purple nutsedge tuber
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Weed Management Strategy

• Diagnose problem
• Evaluate control methods
• Select program
• Execute program
• Evaluate

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Integrated Weed Management

• Preventive
• Cultural
• Biological
• Mechanical
• Herbicides

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Ornamentals

• Initial practices should be preventative
• Remove sources of weed seed prior to bed
  establishment
• Eliminate perennial weeds
• Areas surrounding production sites should be
  mowed and maintained free of weeds

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Ornamentals

• All mulches, media, containers, and pant stock
  introduced into production system should be
  weed-free.
• Maintain ornamentals in a healthy condition to be
  more competitive

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Ornamental Weed Control Options

• Hand-removal, hoeing
• Mulches
• Landscape fabrics
• Herbicides

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Ornamentals

• Cultivation and Hand Pulling
• Can damage ornamentals shallow rooted ornamentals
• Spread perennials
• Hand weeding - often preferred method even though
  expensive and time consuming

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Ornamentals

• Cultivation
• Hand-weeding - high cost, labor intensive
• Not feasible as only means of control
• With certain pant materials, new plantings,
  herbicide use not possible

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Mechanical Control
Hand Pulling and Hoeing

• Best control with small weeds lt4 inches
• Must understand how the weed develops (annuals
  vs. perennials)

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Hand Weed Control
Advantages Disadvantages

• keeps you in shape repetition is a must
• environmentally friendly can stimulate
  germination
• controls most weeds must be timely

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Mechanical Control
Tillage

• Controls many weeds that have emerged
• Incorporate fertilizers, lime
• Prepares seed or plant beds

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Tillage Practices
Advantages Disadvantages

• control most weeds expensive??
• quick and easy cant get too close to
  ornamental plants root pruning

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Mulches

• Plastic or fabric thickness affects the degree of
  weed suppression.
• Clear and colored plastics that allow light
  penetration produce high temperatures in the
  upper surface.
• This build up of heat, solarization, kills
  germinating weed seeds.

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Organic Mulches

• Straw, wood chips, pine straw, sawdust,
  newsprint, and other organic materials.
• These mulches also shade and physically hinder
  germinating seedlings

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Organic Mulches

• Coarse texture better than fine
• Texture more important than type
• 2 to 4 inch depth
• Renew as needed
• Nothing is permanent!

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Landscape Fabrics

• Expensive
• Very good option for homeowners
• Use high quality, non-woven, fused fabric
• Properly mulch

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Mulches
Advantages Disadvantages

• control most weeds expensive??
• good use of waste handling is often
• materials a pain
• Conserves water

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HERBICIDES
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Ornamental Preemergence Herbicides

• Products labeled for various species
• Irrigate-in if possible (1/2 inch) within 7 days
  for preemergence herbicides
• Do not apply to wet foliage
• Match weeds to specific products
• Use fall spring applications
• Rotate products if possible

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How Long do Pres Provide Control?

• Most pres start to break about 60 days after
  application
• Repeat applications are generally needed in the
  humid south for full season control
• Apply second treatment about 60 days after the
  first application

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Weed seeds germinate and are controlled as they
come in contact with the herbicide.
Herbicide layer
Turfgrass roots of established turf below the
herbicide layer
Preemergence herbicides do not prevent weed seeds
from germinating.
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Reasons for Preemergence Herbicide Failure

• Applying after weeds have germinated.
• Failure to water in with at least 0.25 to 0.5
  inches of rainfall or irrigation.
• Gaps in the herbicide barrier.

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Ornamental Herbicides

• Annual grass control available
• Preemergence and postemergence
• Pre and Post broadleaf weed control is difficult
• Use post graminicides for perennial grass control
• Vines, woody plant control is exceedingly
  difficult

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HerbicidesPreemergence Grass Control(dinitroanil
ine)

• Surflan (oryzalin)
• Causes girdling of some conifer species
• Treflan (trifluralin)
• Needs to be incorporated or covered with mulch
• Factor (prodiamine)
• Pendulum (pendimethalin)

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HerbicidesPreemergence Grass Control

• Devrinol (napropamide)
• Safe on many woody plants
• Not as effective for broadleaf control as others
• Pennant Magnum (metolachlor)
• Granular formulation safe to apply to many
  species if foliage dry

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Herbicides Preemergence - Broadleaf Control

• Princep (simazine)
• most widely used preemergence herbicide for
  broadleaf control in woody nursery stock
• several species, especially herbaceous
  ornamentals are injured

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Herbicides

• Ronstar (oxadiazon)
• Granular formulation has safety on broad range of
  woody plants
• Often mixed with Devrinol to broaden range of
  control

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Herbicides

• Goal (oxyfluorfen)
• Dormant or hardened conifers
• Granular formulation can cause damage if applied
  to wet foliage
• Often applied as directed spray

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Herbicides

• Gallery (isoxaben)
• excellent control of broadleaves
• often mixed with dinitroaniline to broaden
  spectrum of control
• some species susceptible
• expensive

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HerbicidesGranular Preemergence Combinations

• Rout (oxyfluorfen oryzalin)
• One of standards in ornamental industry
• Excellent broad spectrum control
• OH2 (oxyfluorfen pendimethalin)
• Another standard treatment

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HerbicidesGranular Preemergence Combinations

• OO-Herbicide (oxyfluorfen oxadiazon)
• Excellent broad spectrum control
• Do not apply to wet foliage

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HerbicidesGranular Preemergence Combinations

• XL (benefin oryzalin)
• Not much improvement over Surflan alone but
  easier to apply
• Derby (simazine metolachlor)
• Limited by potential damage from simazine

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HerbicidesGranular Preemergence Combinations

• Snapshot DF (isoxaben oryzalin)
• Excellent control of most weeds found in
  container nurseries
• Snapshot TG (isoxaben trifluralin)
• Controls broad range of grasses and broadleaves

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Integrated Weed Management

• Integrating preventive, mechanical (mulches,
  fabrics), cultural and chemical methods is
  usually the most effective method of managing
  weeds in ornamentals.

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Florida betony
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Florida Betony - Stachys floridana

• Labitae (mint family)
• Rattlesnake weed
• perennial
• reproduces primarily by tubers
• opposite, serrated leaves
• occurs in turf and ornamentals

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Florida Betony Control

• Roundup, Finale
• Casoron applied in winter
• Use landscape fabric in ornamentals

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Chamberbitter, niruri, gripeweed
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Chamberbitter - Phyllanthus niruri

• Euphorbiaceae (spurge family)
• niruri, gripeweed, leafflower
• summer annual, reproduces by seed
• alternate leaves, numerous leaflets
• inconspicuous flowers
• stalkless green, round fruit
• no milky juice

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Longstalked Phyllanthus
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Longstalked Phyllanthus (Phyllanthus tenellus)

• Euphorbiaceae (spurge family)
• summer annual, reproduces by seed
• alternate leaves, numerous leaflets
• inconspicuous flowers
• stalked green, round fruit
• no milky juice

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Phyllanthus spp. - Control

• Use mulch
• Apply early spring

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Phyllanthus spp. Preemergence Control

• Ronstar (not labeled for use in home landscapes)
• Rout (OHII - slightly less effective)
• Surflan Gallery (Snapshot TG - less effective)
• Prodiamine (Factor, Endurance, Barricade)
• Gallery

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Phyllanthus spp. Postemergence Control

• Roundup Pro
• Finale
• Reward LS

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Phyllanthus spp. Ineffective Herbicides

• Basagran T/O
• Image
• MSMA
• Pennant
• Pendimethalin
• Balan

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Sedge Herbicides -Ornamentals

• Basagran T/O - yellow, annual sedges
• Manage - yellow, purple, annual sedges
• Image - yellow, purple, annual sedges
• Pennant - yellow, annual sedges
• Preemergence only

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Herbicides Selective Postemergence Broadleaf
Control

• Basagran T/O (bentazon)
• Directed application with some over-the-top on
  some species
• Goal (oxyfluorfen)
• Directed applications

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Herbicides PRE and POST Broadleaf

• SureGuard or BroadStar (flumioxazin)
• Controls many problem broadleaf annual weeds

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Herbicides Postemergence Grass Control

• Vantage (sethoxydim)
• Broad range of safety on ornamentals
• Fusilade II, (fluazifop)

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HerbicidesNon-Selective

• Roundup (glyphosate)
• Finale (glufosinate)
• Scythe (pelargonic acid)
• Reward (diquat)

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Ornamental Weed Management

• Summary
• Weed management systems are diverse
• Combinations of mechanical and chemical
  strategies
• Herbicides often provide cost effective weed
  control
• Care must be taken to select herbicides which can
  be used safely, without damage to ornamentals.

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Turfgrass Weed Management
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A Healthy Turf Is The Best Defense Against
Weeds!!!
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Weed ManagementInvolves an Integrated Approach

• Follow Proper Cultural Practices
• Proper Weed Identification
• Prevention of Weed Introduction
• If Needed, Use Herbicides

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Cultural PracticesWeeds love voidsWeeds Do Not
Cause Voids
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Cultural PracticesCultural Practices are Highly
Interrelated

• Fertilization
• Irrigation
• Mowing
• Cultivation
• verticutting
• aeration

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Crabgrass Goosegrass Control

• Numerous herbicides available, but it is
  important to select one that provides consistent
  control.

Brand Name Chemical Name Dimension dithiopyr
Pendulum/PRE-M pendimethalin Ronstar oxadi
azon Balan benefin Surflan oryzalin XL
benefin oryzalin Team trifluralin
oryzalin Barricade prodiamine
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Crabgrass Control in Bermudagrass

• Evaluation of POST herbicides on weed control in
  turfgrasses in Florida.
• 80 commercially acceptable.

TREATMENT 4 DAT 10 WAT MSMA 75 100 Se
ncor 35 70 Illoxan 15 85 Dimension
20 85 Drive (quinclorac) 80 95
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Crabgrass Goosegrass Control in St.
Augustinegrass

• PRE herbicides

Brand Name Chemical Name Balan 2.5G
Benefin Team Benefin Trifluralin Betasan,
Pre-San Bensulide Dimension
Dithiopyr Surflan Oryzalin XL2G Oryzalin
Benefin Ronstar Oxadiazon PRE-M,
Pendulum Pendimethalin Barricade
Prodiamine Atrazine/Simazine
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Crabgrass Goosegrass Control in St.
Augustinegrass

• POST herbicides

None
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Asulox
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Crabgrass Goosegrass Control in Centipedegrass

• PRE herbicides

Brand Name Chemical Name Balan 2.5G
Benefin Team Benefin Trifluralin Betasan,
Pre-San Bensulide Dimension Dithiopyr
Surflan Oryzalin XL2G Oryzalin
Benefin PRE-M, Pendulum Pendimethalin Barricad
e Prodiamine Atrazine/Simazine
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Crabgrass Goosegrass Control in Centipedegrass

• POST herbicides

TREATMENT Atrazine/Simazine Vantage
(Sethoxydim)
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Purple Nutsedge(Cyperus rotundus L.)

• Rapidly spreading perennial with triangular stem.
• Leaves, abruptly tapering at tip, boat shaped.
• Seedhead purplish to reddish brown
• Tubers oblong, covered with hairs, and found in
  chains.
• Tubers bitter to taste (camphor).

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Yellow Nutsedge(Cyperus esculentus L.)

• Rapidly spreading, perennial with triangular
  stem.
• Leaves with long attenuated, needle shaped tip.
• Seedhead yellowish-brown or straw colored.
• Tubers round, lacking hairs and formed at ends of
  whitish rhizomes.
• Tubers sweet tasting.

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Annual Kyllinga(Cyperus sesquiflorus (Torr.)
Mattf. Kuekenth.)

• Annual
• Seedhead with a single elongate-rounded,
  sometimes lobed head.
• Three or four leaves at the top of a bare stem
  just below seedhead.

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Green (Perennial) Kyllinga(Kyllinga brevifolius
Rottb.)

• Mat-forming perennial that grows to 6" tall from
  rhizomes.
• Leaves and stems, dark green.
• Seedhead nearly round or oblong, usually has
  three short leaves just below.
• Reproduces by seed and rhizomes.

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Sedge Herbicides - Turfgrass

• Postemergence
• Basagran T/O - yellow, annual sedges
• Manage - yellow, purple, annual sedges
• MSMA/DSMA - yellow, purple, annual sedges
• Image - yellow, purple, annual sedges
• Monument - yellow, purple, kyllinga
• Certainty yellow, purple, kyllinga
• Preemergence
• Pennant - yellow, annual sedges

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Virginia Buttonweed(Diodia virginiana L.)

• Spreading perennial with hairy branched stems.
• Leaves lance-shaped, joined across the stem by
  membrane.
• White tubular flowers with four lobes ateach
  leaf axil along stem.
• Reproduces by seed, fleshy roots and stem
  fragments.
• Favors moist to wet sites.

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Virginia Buttonweed Control

• Generally found in wet / overwatered sites -
  CORRECT THIS PROBLEM FIRST!

• 2,4-D, Dicamba, MCPP, MCPA (Mixtures)
• 2,4-D is most effective so use product with high
  2,4-D.
• Repeat application 3-4 weeks.
• Manor, Blade some activity
• Quicksilver some activity
• If only a few plants present hand remove,
  including below ground parts

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Pennywort (Dollarweed)(Hydrocotyle spp.)

• Perennial from rhizomes, occasionally with
  tubers.
• Long-stalked leaves with scalloped margins and
  petiole in center of leaf, umbrella-like.
• Flowers in elongated spikes.
• Found in moist to wet sites.

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Pennywort (Dollarweed) Control

• Generally found in wet / overwatered sites -
  CORRECT THIS PROBLEM FIRST!
• Multiple applications, 10 to 14 days apart.
• Injury to turfgrass can be expected.

2,4-D, Dicamba, MCPP, MCPA (Mixtures) - DO NOT
use Dicamba under trees!!! Atrazine/Simazine -
Injury can be expected! 2 applications per year.
Prompt (Atrazine Bentazon) - Does not
control any grasses
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Doveweed(Murdannia nudifolia (L.) Brenan)

• Prostrate runner
• Annual with fleshy, creeping stems, rooting at
  nodes.
• Leaves fleshy, alternate, narrowly lanced-shaped.
• Few hairs at base of leaf blade on margin
• Tiny blue flowers
• Seed in round capsules
• Opportunistic

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Doveweed Control

• 2,4-D, Dicamba, MCPP, MCPA (Mixtures)
• MSMA
• Sencor MSMA
• Atrazine/Simazine
• applied twice 30 days apart
• Prompt

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Lawn Burweed (Spurweed)(Soliva pterosperma
(Juss.) Less.)

• Low-growing, branched, winter annual.
• Leaves divided into narrow segments or lobes.
• Flowers small and inconspicuous.
• Fruits clustered in leaf axils with sharp spines
  that can cause pain and injury to humans.

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Lawn Burweed (Spurweed) Control

• Key is to treat in fall when weeds are small

• Preemergence
• Atrazine/Simazine
• Postemergence
• Atrazine/Simazine
• Prompt
• Sencor
• Trimec Southern
• 2,4-D
• Dicamba
• MCPP

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Residential TurfgrassRecent History

• Products Lost
• At least in Florida

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Asulox
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SpeedZone Southern
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Lontrel

• Lontrel is still labeled for most uses other than
  residential turf.

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• St Augustinegrass has been removed from Spotlight
  label
• Tolerance issues

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New Atrazine Regulations
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Atrazine Label Restrictions(Now Restricted Use)

• This product must not be mixed or loaded within
  50 feet of intermittent streams and rivers,
  natural or impounded lakes and reservoirs.
• Product must not be applied within 66 feet of the
  points where field surface water runoff enters
  perennial or intermittent streams and rivers or
  within 200 feet of natural or impounded lakes and
  reservoirs.
• Users are advised not to apply atrazine to sand
  and loamy sand soils where the water table
  (ground water) is close to the surface and where
  these soils are very permeable, i.e.,
  well-drained.

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Atrazine Label Restrictions(Now Restricted Use)

• Users are advised not to apply atrazine to sand
  and loamy sand soils where the water table
  (ground water) is close to the surface and where
  these soils are very permeable, i.e.,
  well-drained.
• Additional PPE requirements
• Reduced use rates

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Fewer Postemergence OptionsSt.
AugustinegrassGrass Control

• No selective postemergence grass control
• Only option Roundup and re-sod
• Increase use of preemergence

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Fewer Postemergence OptionsBroadleaf Control

• Fewer options than five years ago
• No new options on the immediate horizon

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Any Bright Spots?
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Certainty(sulfosulfuron)

• Recently registered in turfgrass postemergence
• Including St. Augustinegrass excellent
  tolerance
• Monsanto product
• Excellent nutsedge and kyllinga activity
• No control of summer grasses
• Broadleaf control??

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Questions?