Weed Control in Turfgrass Systems

Report
Weed Control in Turfgrass
Systems
Turfgrass IPM Workshop
November 11, 2011
Sarah J. Wilhelm
Colorado State University
Fort Collins CO
Causes of Turf Weed Problems
 Planting poor quality seed
or sod
 Weak, non-competitive turf
 Improper species or cultivar
selection
 Poor management practices
 Damaged by traffic, stress,
pests
Use Weed-Free Seed!
Poa trivialis
Roughstalk bluegrass
Creeping bentgrass
Adequately
fertilized turf
Underfertilized turf
Mowing Height Affects Weed Seed
Germination and Weed Vigor
Necrotic Ring Spot and Weeds
Integrated Weed Management
Program for Turf
Prevent weed introduction
 Properly maintain turfgrasses
 Identify weeds and learn life cycles
 Utilize and evaluate control practices

Cultural
Mechanical
Biological
Herbicide Use
Good Cultural Practices
Weeds Associated With Compacted Soils
Annual bluegrass
 Goosegrass
 Knotweed
 Prostrate Spurge

Weeds Associated With Moist or Poorly
Drained Soils
Annual bluegrass
 Roughstalk bluegrass
 Barnyardgrass
 Bentgrasses

Weeds Associated With Infertile
(Low Nitrogen) Soils
Black medic
 Plantain
 White Clover

Importance of Weed ID
 Learn life cycle and
growth preferences
 Best ways to
manage with cultural
practices
 Effective and LEGAL
herbicide use
Warm-Season (C4) Species
 Most are annuals
 Crabgrass, foxtails,
goosegrass, sandbur,
barnyardgrass
 Purslane, spurge,
knotweed, puncturevine
 Aggressive competitors
with cool-season (C-3)
grasses during the
summer months
Cool-Season (C3) Species
 Bluegrasses, ryegrass,
fescues, bentgrasses are
cool-season turf species
 Dandelion, thistle, bindweed
are cool-season broadleaf
weeds
 Quackgrass, bromegrass,
annual bluegrass are
perennial weedy grasses
 Grow best (and are easiest to
control) during spring and fall
Weed ID Web Sites
North Carolina State University
http://www.turffiles.ncsu.edu/turfid/
Michigan State University
http://www.msuturfweeds.net/
Weed ID and Management Books

Color Atlas of Turf Weeds. 2008. John Wiley
and sons.

Weeds of the West. 1991. The University of
Wyoming.

Identifying Turf and Weedy Grasses of the
Northern United States.
http://pubsplus.uiuc.edu/C1393.html
Classes of Turf Weed Problems




Annual grassy weeds
Perennial grassy weeds
Sedges
Broadleaf (dicot) weeds
Grassy Weed Control is Difficult


Infestation often goes
unnoticed until it has
become a major problem
Selective control can be
difficult
Species often related –
sometimes same genus
 Limited chemistry/number of
herbicides

Annual Grassy Weeds
Summer Annuals
 crabgrass
 goosegrass
 foxtails
 barnyardgrass
 annual (?) bluegrass
 winter annual bromes
Preemergence Herbicides











benefin (Balan)
benefin + trifluralin (Team)
bensulide (Betasan)
corn gluten meal (Amaizing Lawn, WOW, many others)
dithiopyr (Dimension)
isoxaben (Gallery) – broadleaf weeds only
oxadiazon (Ronstar)
pendimethalin (Pre-M, Pendulum, Scotts home products)
prodiamine (Barricade)
siduron (Tupersan) – for use at time of seeding
mesotrione (Tenacity) – both pre- and postemergence for
annual grasses
Pre-emergence Herbicides…
DON’T kill weeds seeds
DON’T sterilize the soil
DON’T control weeds you can already see
(except for dithiopyr/Dimension)
DON’T harm trees and other landscape
plants whose roots are growing in the lawn
CAN harm the roots of desirable turf
Annual Grass Control Ratings
Herbicide
Benefin (Balan)
Benefin + oryzalin
Benefin + trifluralin (Team)
Bensulide (Betasan)
Dithiopyr (Dimension)
Oryzalin (Surflan)
Oxadiazon (Ronstar)
Pendimethalin (Pendulum)
Prodiamine (Barricade)
Crabgrass
Foxtails
Goosegrass
Annual
Bluegrass
G
G-E
F-G
E
G-E
G-E
G
G-E
G-E
F
F-G
F
P
F-G
F-G
G-E
F-G
F-G
G-E
G-E
G-E
P-F
G-E
G-E
G-E
G-E
G-E
Corn Gluten Meal for
Natural/Organic Weed Control








Preemergence herbicide activity ONLY
Excellent N source (10% N)
Cost is about $1.00/pound
Use rate of 20 pounds/1000 sq. ft. provides 2 lbs.
N/1000
Processed CGM provides moderate control of
crabgrass and other annual weeds
Will not provide long-term control of perennial
weeds
Raw corn meal is NOT effective
Must use licensed sources of GGM to apply legally!
Causes of Unsatisfactory Preemergence
Herbicide Performance










Applied after weed emergence
Rate applied was too low
Non-uniform application
Insufficient (at application) rainfall or irrigation
Excessive rain immediately after application
High rainfall year
Poor site drainage
Drought
Excessive/prolonged summer heat
Clippings collected before preemergent incorporated
Preemergent herbicide skip
Preemergence Herbicide Efficacy

Loss of activity may occur if not watered in
within 7 to 10 days.

Losses from photodecomposition and
volatilization can be important, especially with
sprayable formulations

Avoid clipping collection
Split Preemergent Herbicide
Applications
Single application
at higher rate
Phytotoxicity level
Effective control level
Herbicide
Concentration
1st
Application
2nd
Application
Time
Perennial Weedy Grass Species








Tall fescue
Quackgrass
Bromegrass
Bentgrass
Zoysiagrass
Bermudagrass
Poa annua
Poa trivialis
Sources of Perennial Grassy Weeds






Contaminated seed or sod
Propagules present in soil at establishment
Introduced in topsoil, organics, topdressing,
nursery materials (tree balls)
Encroachment from adjacent landscape (neighbor
lawns, golf courses, farmland, rangeland)
Tracking by equipment, people, animals
Intentionally planted
Zoysiagrass patches in Kentucky bluegrass lawn
Managing Perennial Grassy Weeds


Glyphosate (Roundup),
followed by reseeding
or sodding
Learn to tolerate the
different grass species
There are new herbicides available for application by lawn care professionals
that can be used to SELECTIVELY remove tall fescue, creeping bentgrass,
rough bluegrass, quackgrass, windmillgrass, nimblewill and bermudagrass from
Kentucky bluegrass lawns. PROPER IDENTIFICATION IS ESSENTIAL!!!
Rough bluegrass (Poa trivialis)
Quackgrass (Elytrigia repens)
 Coarse, blue-green





leaves
Aggressive rhizome
former
Rolled vernation
Early spring green-up
Common ag and
ditchbank weed
Can be selectively
controlled in bluegrass
turf with Certainty
herbicide (sulfosulfuron)
Tenacity (mesotrione)







Has a novel mode of action based on a naturally produced compound from
the bottlebrush plant (Callistemon citrinis)
Absorbed by leaves, shoots, and roots and rapidly translocated in the xylem
and phloem of susceptible plants
Prevents carotenoid production in leaves, leading to destruction of chlorophyll
and cell membranes
Highly active at low use rates as a pre- and post-emergence herbicide
Provides selective broad-spectrum dicot and monocot weed control in a
number of turf species
Can use at or prior to seeding of proposed labeled turfgrass species
Low toxicity to wildlife and aquatic organisms and short persistence in the
environment
Mesotrione (Tenacity) for Bentgrass Control in
Ryegrass and Kentucky Bluegrass
Syngenta Company




2 applications 0.25 lb
ai/A, at 10-14 interval
3 applications 0.17 lb
ai/A, at 10-14 day interval
80-90% control at 15
weeks after treatment
Preemergent and
postemergent activity on
crabgrass, some
broadleaf weeds
Grasses and Sedges Controlled by Tenacity
Barnyardgrass (pre and post)
Creeping bentgrass (post)
Crabgrass species (pre and post)
Foxtail, Yellow (pre and post)
Goosegrass (pre and post)
Nimblewill (post)
Yellow nutsedge (post)
Windmillgrass (post)
Turf Species Labeled for
Tenacity
Kentucky bluegrass (including Texas x
KBG hybrids) 0.16-0.25 lb. ai/a
 Perennial ryegrass – 0.16 lb. ai/a
 Tall fescue 0.16-0.25 lb. ai/a
 Fine fescues (red, Chewings, hard)
0.16 lb. ai/a

Dicot Weed Control
Perennials
 Dandelion, clover, bindweed,
thistle, plantain, violet
Annuals
 Spurge, puncturevine, oxalis,
purslane
Prevention
 Proper establishment
 Ongoing maintenance
Herbicides
 Gallery (good), grass
preemergents (fair)
 Many postemergent options
Dicot Weeds Can Be Difficult to Control
 Control is contingent upon
herbicide uptake and
translocation
 Death of the weed may be
slow
 Mature weeds may not be
controlled completely
Postemergent Herbicide “Failure”



Weeds curl and
discolor, but don’t die
Weeds appear to have
died, but come back
Reasons...
 Weed species
 Weed age
 Weed health/vigor
Seedlings are easier to control than
are mature weeds
Drought-stressed weeds
poor herbicide uptake
poor translocation
difficult to kill
Actively growing weeds
good herbicide uptake
rapid translocation
more easily killed
Postemergent Broadleaf Herbicides

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2,4-D (many names, often with other herbicides)
dicamba (Banvel)
MCPP, mecoprop (many brands)
MCPA (many)
dichlorprop
triclopyr (Turflon Amine, Turflon Ester)
clopyralid + triclopyr (Confront)
quinclorac (Drive)
clopyralid (Lontrel)
chlorsulfuron (Corsair)
metsulfuron methyl (Manor)
carfentrazone-ethyl (Quicksilver; component of Speed Zone, Power Zone)
sulfentrazone (Dismiss) (component of Surge and Q4)
mesotrione (Tenacity) Golf and sod only; residential label expected late 2009
sulfosulfuron (Certainty)
Postemergent Broadleaf Herbicides

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








2,4-D (many names, often with other herbicides)
dicamba (Banvel)
MCPP, mecoprop (many brands)
MCPA (many)
dichlorprop
triclopyr (Turflon Amine, Turflon Ester)
clopyralid + triclopyr (Confront)
quinclorac (Drive)
clopyralid (Lontrel)
chlorsulfuron (Corsair)
metsulfuron methyl (Manor)
carfentrazone-ethyl (Quicksilver; component of Speed Zone, Power Zone)
sulfentrazone (Dismiss) (component of Surge and Q4)
sulfosulfuron (Certainty)
mesotrione (Tenacity) Golf courses and sod only; residential label expected 2010
Dicot Weeds Controlled by Tenacity
Buttercup/Ranunculus (post)
Chickweeds (pre and post)
Clover (pre and post)
Dandelion (post)
Oxalis (post)
Speedwell species (post)
Canada thistle (post)
Sowthistle (post)
Dismiss



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

Sulfentrazone
Safe on most cool- and
warm-season turf
species
Excellent for sedge
control
Good for annual
broadleaf weeds
Rapid activity
Shoot and root uptake
Surge







Sulfentrazone, with 2,4-D, MCPP, dicamba
Cool-season grasses and buffalograss
Water-based amine, low odor
For weed control when >90 F
Fast-acting (24-48 hrs)
Photosynthetic inhibitor
Dandelion, clover, oxalis, spurge,
knotweed, plantain
Q4 Plus






Quinclorac
Sulfentrazone
2,4-D (amine salt)
Dicamba (amine salt)
Excellent cool-season turf
safety
Controls annual grassy
weeds and long list of
annual and perennial
broadleaf weeds
Manor (metsulfuron methyl)





For use on Kentucky bluegrass, fine fescue
and buffalograss lawns
Will damage perennial ryegrass
Low use rates: 0.125 to 0.5 oz. product/acre
Controls ryegrass, thistle, spurge, oxalis,
filaree, yarrow, kochia, knotweed, dandelion,
most legumes
Nufarm Turf and Specialty
http://www.turf.us.nufarm.com/
Control of Some Common
Broadleaf Weeds
Black medic (Medicago lupulina)



Healthy turf
Increase N fertility
Preemergent control


Gallery
Postemergent control

MCPP, MCPA
 Drive
 Clopyralid products
Yarrow (Achillea)



Healthy turf
Increase N fertility
Preemergent control


none
Postemergent control

3- and 4-way products
 Clopyralid products
VERY DIFFICULT WEED!
Bindweed (Convolvulus)



Healthy turf suppresses it
Increase N fertility
Preemergent control


none
Postemergent control

3- and 4-way products
 Clopyralid products
 Drive, Q4 VERY good!
A New Weed Species Found in
Colorado
Establishes quickly
 Deep Rooted
 Resistant to conventional herbicides

CSU Turf Program Web Site
http://csuturf.colostate.edu

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