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Responding to Lawn Weed Management Questions

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3-4 lb N/1000 ft2: Holiday Schedule. Irrigation. Turf species ... High use rates (12-20 lb/M) One to two applications annually ... – PowerPoint PPT presentation

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Title: Responding to Lawn Weed Management Questions


1
Responding to Lawn Weed Management Questions
  • Dr. John Stier
  • University of Wisconsin-Madison
  • Environmental Turfgrass Extension Specialist

2
Presence of Weeds Usually Indicates Underlying
Problem
  • Turfgrasses adapted to the local environment
    resist weeds best

3
Good Turf Management
  • Mowing
  • 2-3 inch height 1/3 Rule
  • Sharp blades
  • Fertility
  • 3-4 lb N/1000 ft2 Holiday Schedule
  • Irrigation
  • Turf species
  • Kentucky bluegrass/perennial ryegrass
  • Fine fescue low maintenance, dry shade
  • Rough or supina bluegrasses for moist shade

4
Moss and Algae
  • Low light
  • Restricted air movement
  • Poor drainage
  • Often compounded by poor management

5
Why do I Have Weeds in My Lawn Again This Year?
  • Correct product used?
  • Age, storage
  • Rate?
  • Timing?
  • Rain, growing conditions
  • Temperature
  • Low-restrict absorption/translocation
  • Warm to mod. high-best absorption/translocation
  • V. high-dries on surface prior to absorption
  • Turf cover management

6
Post-Emergent Grassy Weed Control
  • Difficult
  • Annuals crabgrass
  • MSMA retail
  • Perennials tall fescue, bentgrass, quackgrass,
    nimblewill
  • Glyphosate (Roundup, Kleenup)

7
Creeping Bentgrass
  • Poor quality seed
  • May take years to become noticeable
  • Puffy patch, small-leaved grass
  • Fine stolons easily ripped up
  • Spray glyphosate
  • 1 ft past perimeter
  • of patch

Bentgrass patch
1 ft
stolons
8
Pre-Emergent Weed Herbicides
  • Form barrier between soil surface and seed
  • Irrigation or rainfall
  • Prevent seed germination
  • apply March-April
  • Used for annual grasses, some broadleaves
  • Will stop perennial germination
  • Examples pendimethalin
  • dithiopyr (some post-emergent)
  • siduron--OK for seeding

9
Crabgrass and Quackgrass
  • Spring and summer
  • Light green color
  • Brown after frost
  • Short, wide leaves
  • Fine hairs on leaves/stem
  • Easy to pull plant
  • Perennial
  • Gray-green color
  • Longer, narrower leaves
  • Few hairs
  • Auricles
  • Cant pull plant
  • Rhizomes

10
Post-Emergent Broadleaf Herbicides
  • Apply to visible weeds when actively growing
  • Broadleaf weed control 2,4-D MCPP MCPA
    dicamba triclopyr
  • Sold in combinations (e.g., Weed-B-Gon)
  • Dicamba is soil mobile, can damage taxus,
    junipers, others

11
Factors Affecting Herbicide Control
Wild violet
  • Formulations
  • Esters
  • volatile
  • readily absorbed
  • use during cool temps or hard-to-kill weeds
  • Salts
  • less volatile
  • use during hot temps
  • less smell

12
Weed and Feed Products
  • Herbicide impregnated on fertilizer prill
  • Post or pre-emergence
  • Post Stick to leaves?
  • Pre Timing?

13
Non-Toxic Pesticides
  • Misnomer Pesticides intended to be toxic to
    pests
  • EPA regulates toxicity no significant danger
    when used properly
  • Avoid reliance on non-regulated biological or
    organic pesticides
  • May not work
  • No toxicity testing!

14
LD50 and LC50 Measure Rate Acute Toxicity
  • Amount to kill 50 of animals Lethal Dose to
    50 (LD50)
  • LC50 Inhalation Toxicity
  • Lower LD or LC50 values More toxic!

15
Toxicity of Common Substances
LD50
3500 ppm 10 oz ai/180 lb adult
Source Pesticide profiles Toxicity,
environmental impact, fate. 1997. M.A. Karmin
(ed). Lewis Publishers Source Applied weed
science. 1999. M.A. Ross C.A. Lembi.
Prentice-Hall.
16
EPA 2,4-D Not Linked to Human Cancer (9 Aug.
2007)
  • 300 studies since 1989
  • "Based on extensive scientific review of many
    epidemiology and animal studies, the Agency finds
    that the weight of the evidence does not support
    a conclusion that 2,4-D, 2,4-DB and 2,4-DP are
    likely human carcinogens," according to a notice
    released by EPA.

17
Pesticide Fate
Photodecomposition
(Volatilize)
Pesticide Applied
(Drift)
Runoff ?
Plant Uptake Degradation
Thatch Adsorption
Microbial decomposition
Soil Chemistry Reactions and Decomposition
Leaching?
18
Corn Gluten Meal
  • Accidental discovery
  • Research-based!
  • Activity
  • Herbicidal(?)
  • Fertility (10 N)

19
Corn Gluten Meal Application
  • 12-20 lb/M
  • Early spring
  • Late summer
  • Irrigate
  • Timing critical
  • Short-lived peptides

20
Crabgrass Reduction in Field Trials of Corn
Gluten Meal on Kentucky Bluegrass
Adapted from Christians, N.E. 1993. The use of
corn gluten meal as a natural preemergent weed
control in turf. ITS No. 7. Intertec Publishing
Corp., Overland Park, KS, p. 284-290.
21
Corn Gluten Meal for Weed Control
  • High use rates (12-20 lb/M)
  • One to two applications annually
  • Expensive 25-45 per application/M
  • Pre-emergent only
  • Overseeding limitations
  • Fertility effect

22
Other Ways to Reduce Risk
  • Use pesticides only when necessary
  • Integrated Pest Management
  • Choose products with lower toxicities
  • Follow ALL label instructions
  • Gloves, rates, disposal
  • Remember
  • Risk Toxicity x Exposure!

23
Conclusion
  • A little herbicide goes a long way if
  • Turf is properly managed!
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