Landscape Weed Control

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Landscape Weed Control

• Russell W. Wallace, Ph.D.
• Extension Horticulture Weed Specialist

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For more Expert Advice go tohttp//aggieturf
.tamu.edu http//aggie-horticulture.tamu.edu
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Why control weeds?
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Why control weeds?

• Appearance
• Weeds compete for
• Nutrients
• Moisture
• Light
• Space
• Profits ()
• Website http//www.wssa.net/

Ground Ivy
Courtesy of the Weed Science Society of America
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How to control weeds?
Many choices for complex landscapes
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Some definitions of a weed

• A plant that is growing out of place.
• A plant that has no known benefit to man.

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Weed Biology critical for understanding how to
best control individual weeds.
Yellow nutsedge
Grasses Broadleaves Sedges Annuals Perennials
Yellow foxtail
Carelessweed
Weed Science Society of America
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Courtesy of the Weed Science Society of America
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Courtesy of the Weed Science Society of America
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Sedge weeds
Courtesy of the Virginia Tech Weed ID Guide
Courtesy of the Weed Science Society of America
Courtesy of the Weed Science Society of America
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Weed Control Methods

• Chemical
• Cultural
• Mechanical (physical)
• Biological
• Preventative

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Integrated Weed Management The use of two or
more of the recognized weed control categories.
Mechanical (physical)
Chemical
Preventative
Cultural
Biological
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Chemicals

• Manufactured herbicides for controlling
  perennial and annual weeds in landscapes and
  lawns.

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Timing of Chemical Sprays

• Preplant incorporated (PPI)
• Applied before planting, mixed into the soil.
• Preemergence (PRE)
• Applied to soil before planting/weed emergence.
• Postemergence (POST)
• Applied after crop emerges.
• Post-directed (P-DIRECT)
• Applied after crop emergence, directed around
  crops.

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Herbicide Classification
Grass killers Broadleaf killers Contact System
ic Selective Non-Selective
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What happens to herbicides after they are
sprayed on soil?
Volatilize and move through air
(drift). Degraded by sunlight or soil
microorganisms. Get tied up in soil clay or
organic matter or leach down out of soil
zone. Move with soil moisture and are taken up
by the roots or shoots of plants.
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What happens to herbicides after they are sprayed
on plants?
Volatilize and move through air (drift). Stay
on leaf surface as either a liquid or
crystal. Penetrate the leaves and stay within
(dont move). Penetrate the leaves and move
throughout the plant into the stems, branches,
other leaves and roots.
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Herbicide Selectivity
Herbicide placement POST vs. PRE (soil
depth) Rate of application Anatomical
differences Foliar retention (waxy
leaves) Protected growing points Plant/variety
differences Different plant growth
stages Dormancy of crop at time of
application Seed vs. Transplant
Chicory Rate Response
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Herbicide Selectivity
Leafy Vegetables
Use of antidotes (safeners) Pennant Magnum,
Eptam Localized application of absorbents
Activated charcoal Internal plant
factors Translocation to other sites Absorption
to inactive sites Different crop
metabolism Resistance at site of action
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Herbicide Absorption
Leaves (Postemergence) Shoots (Preemergence
Postemergence) Roots (Preemergence)
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Surfactants, Wetting Agents, Stickers Spreaders
Uniform spreading of spray solutions. Help
spray to remain on leaf surface. Assure that
droplets do not remain suspended on leaf
hairs. Partially solubilize the plant surface to
allow better penetration.
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Herbicide Formulations
Wettable Powders (WP) Emulsifiable Concentrates
(EC) Water Dispersable Granules (WDG) Granules
(G) Soluble Powders (SP) Liquids
(L) Microencapsulated (M) Aqueous Suspension
(AS)
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Herbicide Active Ingredients
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Cultural

• Hand pulling
• Hoeing
• Water
• management
• Mulching
• Competition

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Cultural

• Hand pulling
• Hoeing
• Water
• management
• Mulching
• Competition

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Mechanical (physical)
South Plains Food Bank Farm

• Rototilling
• Weed fabrics
• Mowing
• Weed eaters

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Preventative

• Obey local, state, federal and international laws
  regulated seed transportation.
• Use certified weed-free seed for
  lawns/landscapes.
• Use weed-free composted products.
• Clean rakes, hoes, rototillers, mowing equipment,
  and even shoes between yards and gardens.
• Eliminate weeds near or around yards, ditches or
  cultivated fields (prevent them going to seed).
• Practice zero tolerance.
• Practice resistance management.

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Organic Mulches

• Bark (grounded/chipped) and wood chips
• Attractive, suppress weeds, may float with heavy
  rains.
• Grass clippings
• Physical suppression.
• Watch out for herbicides that were previously
  applied to the lawn.
• Good source of added nitrogen to garden beds.

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Other Organic Mulches

• Newspapers (shredded)
• Readily available, inexpensive, suppress weeds.
  Susceptible to high winds, watch out for earwigs,
  and ink could possibly be toxic.
• Pine needles
• Harder to get hold of, help to decrease soil pH
  (more acid), leachates can suppress weeds, but
  are slow to break down.
• Sawdust
• Improves soil organic matter, inexpensive, could
  cause problems with water penetration, and may
  alter the nitrogen balance in the soil (may need
  to add more nitrogen). Watch out for toxic
  chemicals in wood.

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Using Herbicides on the Lawn and in the Landscape
Bed

• Always read and follow the label instructions!
• Watch out for drift or volatilization to
  non-target plants and areas, residual carryover,
  plant injury, and plant death, etc. Roundup and
  other growth regulator (2,4-D) type herbicides
  can cause major damage and potential lawsuits.

Some plants are extremely sensitive!
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Herbicide Labels

• Always read and follow label instructions.
• Be sure to know application timing and methods,
  label restrictions, areas of use, weeds
  controlled, crop/plant use, and human safety
  information.
• Precautionary Statements (on all labels)
• Harmful if swallowed. Do not breathe spray mist.
  Avoid contact with skin, eyes and clothing.
  Users should wear long sleeve shirts and long
  pants or equivalent, chemical resistant gloves
  and boots. Wash thoroughly after handling and
  before eating and smoking. Avoid contamination
  of feed and food-stuffs. Keep children and pets
  off the treated area until the spray has dried.
  Food utensils such as teaspoons and measuring
  cups should not be used for food purposes after
  use with this product.

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What causes herbicide misapplications and costs
you money?

• Problems can be caused by
• Wrong time of year (too cool or too hot).
• The wrong rate (too much or little).
• Too much overlap or no overlap.
• Rainfall too soon after POST applications.
• No rainfall or irrigation after PRE applications.
• Wrong herbicide for the job.
• Tank-mixes not compatible.
• Improper incorporation (volatilizes,
  photodegrades).
• Nozzles not properly calibrated.

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Growth Regulator Injury with Herbicides
Leaf symptoms from Trimec type herbicides applied
to lawn nearby!
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Spraying Herbicides
Remember Herbicides are intended to kill plants!
The hazards of spraying!
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PreemergenceHerbicidesA Quick ReviewAlways
read and follow current label instructions!
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Casoron 4G(Dichlobenil)

• Preemergence control
• Granular product applied in early spring or late
  fall to soil surface (100 150 lbs/A) around
  established ornamental shrubs and trees. May
  injure herbaceous annual and perennial bulbs.
• Residual
• Good weed control for 2 6 months.
• Controls
• Approximately 60 perennial and annual weeds.

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Gallery 75DF(Isoxaben)

• Preemergence control
• Sprayable product applied for control of certain
  broadleaf weeds in established turf, landscape
  ornamentals, container grown ornamentals, ground
  covers/perennials, ornamental bulbs, non-bearing
  fruit and nut trees/vineyards, Christmas trees,
  and non-cropland areas.
• Soil residual
• Effective weed control for 5 -6 months.
• Controls
• Prevents 95 perennial and annual weeds.

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Pennant Magnum(s-Metolachlor)

• Preemergence control
• Sprayable liquid product applied for use on
  ornamentals and warm-season turfgrasses, and in
  nurseries. Used alone or tank-mixed or applied
  with fertilizers.
• Soil residual
• Effective weed control for 2.5 3.5 months.
• Controls
• Prevents yellow nutsedge, crabgrass as well as 20
  other turf and ornamental weeds.

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Surflan AS or WDG(Oryzalin)

• Preemergence control
• Sprayable liquid or granular product applied for
  use on landscape and container ornamentals,
  ornamental bulbs, ground covers, perennials,
  noncropland uses, and established warm season
  turfgrasses.
• Soil residual
• Effective weed control for 1.0 3.0 months.
• Controls
• Prevents 27 grasses, 25 broadleaf weeds and
  suppresses 16 others.

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Ronstar G(Oxadiazon)

• Preemergence control
• Granular product applied for use on ornamental
  shrubs and trees, and in established lawn and
  recreational turfgrasses (bermudagrass, St.
  Augustinegrass, perennial ryegrass, buffalograss,
  bentgrass, etc.).
• Soil residual
• Effective weed control for 2.5 months.
• Controls
• Prevents 12 grass and 27 broadleaf weeds.

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Pendulum AquaCap(Pendimethalin)

• Preemergence control
• Sprayable product applied for use in established
  lawns, recreational turfgrasses and grounds
  maintenance, noncropland and ornamentals
  production.
• Soil residual
• Effective weed control for 3.0 months.
• Controls
• Prevents 21 grass and 25 broadleaf weeds.

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Barricade 4L or 65WG(Prodiamine) a.k.a. Factor

• Preemergence control
• Sprayable product applied for use in established
  lawns (not on golf courses) container,
  field-grown and landscape ornamentals,
  established wildflower plantings, etc.
• Soil residual
• Effective weed control for 3.0 or more months.
• Controls
• Prevents 30 grassy and broadleaf weeds.

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Princep 4L(Simazine)

• Preemergence control
• Sprayable product applied for use in established
  turf including golf courses, residential and
  commercial lawns, nurseries, and landscape and
  ornamental plantings.
• Soil residual
• Effective weed control for 3.0 or more months.
  Prolonged use can lead to weed resistance.
• Controls
• Prevents 47 grassy and broadleaf weeds.

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Treflan or Preen(Trifluralin)

• Preemergence control
• Sprayable and granular products for controlling
  weeds around established annual and perennial
  flowers, roses, shrubs, ground covers, trees,
  etc.
• Soil residual
• Effective weed control for 2.0 to 3.0 months, can
  be applied at any time.
• Controls
• Over 20 annual grasses, and 14 broadleaves.

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PostemergenceHerbicidesA Quick ReviewAlways
read and follow current label instructions!
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Basagran T/0(Bentazon)

• Postemergence control
• Sprayable product for controlling broadleaf weeds
  and nutsedge in cool and warm-season turfgrasses
  and ornamentals.
• Applications
• Needs to be sprayed with a COC. Applications on
  ornamentals should be as a directed-spray or
  possible injury may occur. Do not mow turf for
  at least 3 days to enhance control. May repeat
  applications 10 14 days later for improved
  control.
• Controls
• Yellow nutsedge, annual sedges, purslane, lawn
  burweed, thistles, wild mustard, spurweed,
  ragweed and dayflower.

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Envoy(Clethodim)

• Postemergence control
• Sprayable product for selective, systemic control
  of grass weeds for over-the-top applications in
  broadleaf ornamentals, conifer trees, non-bearing
  food crops, non-crop or non-planted areas.
• Applications
• Needs to be sprayed with a COC. Applications on
  grassy ornamentals should be as a directed-spray
  or possible injury may occur. Some minor
  spotting or leaf/flower damage may occur to some
  broadleaf ornamentals. Temperature and drought
  sensitive. May take 10 14 days for symptoms
  and plant death to occur.
• Controls
• Annual and perennial grasses. Does not control
  broadleaf weeds or nutsedge (nutgrass).

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Reward(Diquat)

• Postemergence control
• Sprayable product for non-selective, contact
  control of grass and broadleaf weeds using
  over-the-top, directed applications in and around
  ornamentals plantings.
• Applications
• Needs to be sprayed with a NIS. Watch out for
  drift to desirable plants as leaf spotting and/or
  death may occur. Is not temperature sensitive,
  will work well in both cool and hot temperatures.
  Watch out for high mammalian toxicity with this
  product!
• Controls
• Controls all annual weeds that are small and that
  do not have well-developed root systems. Will
  not control perennial grasses or broadleaf weeds,
  though it will burn down the tops.

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Ornamec/Grass-B-Gon(Fluazifop)

• Postemergence control
• Sprayable product for selective, systemic control
  of grass weeds for over-the-top applications in
  broadleaf ornamentals, nurseries and landscape
  plantings. Can be used to control bermudagrass
  in zoysiagrass and tall fescue.
• Applications
• Needs to be sprayed with a NIS. Applications on
  grassy ornamentals should be as a directed-spray
  or possible injury may occur. Some minor
  spotting or leaf/flower damage may occur to some
  broadleaf ornamentals. Temperature and drought
  sensitive. May take 10 14 days for symptoms
  and plant death to occur.
• Controls
• Annual and perennial grasses. Does not control
  broadleaf weeds or nutsedge (nutgrass).

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Finale(Glufosinate)

• Postemergence control
• Sprayable product for nonselective, burndown
  control of grass and broadleaf weeds in noncrop
  areas (around buildings, landscape trimming,
  driveways, paths. etc.), dormant bermudagrass and
  ornamental and in Christmas trees.
• Applications
• Watch out for drift and non-target leaf damage or
  plant death. Can be tank-mixed with other PRE
  herbicides. Applications can be broadcast or
  banded, or spot treatment. Heat and moisture
  stress may influence weed control.
• Controls
• Annual and perennial grasses for burndown only.
  Regrowth may occur due to weed stage, low use
  rate or environmental conditions.

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Roundup, etc.(Glyphosate)

• Postemergence control
• Sprayable product for nonselective, systemic
  broad-spectrum control of grass and broadleaf
  weeds for industrial, turf and ornamental uses.
• Applications
• Watch out for drift and non-target damage or
  plant death. Can be tank-mixed with other PRE
  herbicides. Applications can be broadcast or
  banded, or spot treatment. Heat and moisture
  stress may influence weed control.
• Controls
• Annual and perennial grasses. Some regrowth may
  occur due to weed stage, low use rate or
  environmental conditions.

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Sedgehammer(Halosulfuron)

• Postemergence and preemergence control
• Sprayable product for selective, systemic control
  of nutsedge for industrial uses, and
  cool-season/warm-season turf and for established
  woody ornamental and landscaped uses.
• Applications
• Use a NIS for POST control. Watch out for drift
  and non-target damage. Can be tank-mixed with
  Roundup. Applications can be broadcast or
  banded, or spot treatment. Heat and moisture
  stress may influence weed control. Allow 4 weeks
  between applications and any new plantings.
• Controls
• Yellow and purple nutsedge, and some small
  broadleaf weeds.

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Vantage/Grass Getter(Sethoxydim)

• Postemergence control
• Sprayable product for selective, systemic control
  of grass weeds for over-the-top applications in
  broadleaf ornamentals (including bedding plants,
  public recreation areas, shrubs, groundcovers,
  etc.), non-bearing food crops, non-crop or
  non-planted areas.
• Applications
• Needs to be sprayed with a COC. Applications on
  grassy ornamentals should be as a directed-spray
  or possible injury may occur. Some minor
  spotting or leaf/flower damage may occur to some
  broadleaf ornamentals. Temperature and drought
  sensitive. May take 10 14 days for symptoms
  and plant death to occur.
• Controls
• Annual and perennial grasses. Does not control
  broadleaf weeds or nutsedge (nutgrass).

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Natural or OrganicHerbicidesA Quick
ReviewAlways read and follow current label
instructions!
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Corn gluten meal

• Preemergence control
• Granular, use around established vegetables
• Use in West Texas
• Vegetable gardens and lawns
• Retail name
• Vegetable Garden Weed Preventer (Preen)
• Corn Weed Blocker (Down to Earth)
• Controls
• 9 grasses, 10 broadleaves (including crabgrass,
  dandelion, pigweed and lambsquarters).

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Corn gluten meal

• Mechanism of action
• Prevents the normal development of roots from
  sprouting seeds. Does not kill directly but
  causes seedlings with less than normal root
  systems to succumb to dehydration when exposed to
  drought stress.
• Symptomology
• Deformed emerging weeds.
• Soil residual
• Use 10 20 lbs/ 1000 sq. ft, up to 4 6 weeks
  residual.
• Unique characteristics Biological by-product,
  must be watered in, no control for
  established weeds.

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Essential plant oils(clove, thyme, cinnamon)

• Postemergence control
• Sprayable contact, non-systemic, broad-spectrum
  burndown products for use in ornamentals,
  vegetables and noncrop areas. Will not kill
  growing points that are not contacted by
  herbicide.
• Retail names
• Xpress, Matran II, Weed Zap, Natures Glory Weed
  and Grass Killer
• Controls Have no soil activity.

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Scythe(Pelargonic Acid)

• Postemergence control
• Contact, non-selective control of grasses and
  broadleaf weeds prior to planting.
• Applications
• Applications on ornamentals, etc. should be as a
  directed-spray or possible injury may occur.
  Symptoms and plant death (rapid cellular death)
  occurs within 24 hours. Foliage will turn black
  and water-soaked within hours.
• Controls Annual grasses and broadleaves.

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Vinegar (acetic acid)

• Postemergence control
• Concentrated vinegar 25 acetic acid, cooking
  vinegar 5. Used as a preplant burn down, or
  directed spray in ornamentals, noncrop uses, etc.
  Sprayable product with contact, broad-spectrum
  activity on grasses and broadleaves.
• Retail names
• Burnout II Weed Grass Killer (also contains
  lemon juice and clove oil).
• Natures Glory Weed Grass Killer
• Controls
• Multiple annual grasses and broadleaves, will not
  kill the growing points of plant unless
  contacted. Can cost up to 65/A or more.

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Any Questions? Contact information rwwallace_at_ag
.tamu.edu http//lubbock.tamu.edu/horticulture/