ne turf conference turf fundamemtals weed control · 3 after 3rd2,4-d app and regrowth effect of...

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Turf essentials:Lawn weed control

Zac Reicher

http://turf.unl.edu/

http://turf.unl.edu

http://turf.unl.edu

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Cultural practices for thick turf

• Highest mowing height

• Mow frequently

• Reduce irrigation

• Fertilize primarily in the fall

• Manage traffic/compaction

Managing resistance

• Maximize cultural controls

• Use high label rates

• Alternate modes of action

2,4-D susceptible

2,4-D tolerant

After 2,4-D app and regrowthAfter 2nd 2,4-D app and regrowth

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After 3rd 2,4-D app and regrowth Effect of Drive or Tenacity on late‐season crabgrass in a driving range tee and adjacent golf course rough. Initial applications made on 25 Aug 2008 and MSO included at 1.5 pts/A on all Drive apps other than where stated (Purdue 2008).

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Quin 75 DF0.75 lbs ai/Aw/o NIS

Quin 75 DF0.75 lbs ai/A



Quin XLR80.75 lbs ai/A

Mezo 0.25 lbsai/A

Untreated

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Crabgrass

• Summer annual

– Germinates in spring

– Sets seed in summer

– Dies with frost

• Can produce 150 tillers and 150,000 seeds per plant

• 1,000 seeds/plant X 10% viable = 100 germinating seeds

• 100 germinating seeds X 95% control =5 plants where 1 was last summer

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August crabgrass control from April‐applied preemergence herbicides over three years in studies at Purdue University. Applied to low‐mowed Kentucky bluegrass to encourage crabgrass.

August crabgrass control from April‐applied preemergence herbicides over three years in studies at Purdue University. Applied to low‐mowed Kentucky bluegrass to encourage crabgrass.

Effect of formulation and rate of Dimension on crabgrass control over two years (UNL, 2014) (apps made late Apr fb late June)

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% Crabgrass control in August

lbs AI/Acre

15‐3‐520‐0‐4EWWSP

PRE/fertilizer combos

• Watch the N rate!• Increase slow release % with rates >0.7 lbs N/1000

• Most cool‐season lawns require little N in spring

• Cannot reduce N rate without reducing PRE rate

• Granule size

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50 lbs 19-0-7 with 0.15% Dimension 50 lbs covers 13,000 sq ft

50 lbs 19‐0‐7 Dimension 0.0015 lbs ai 43,560 sq ft 0.25 lbs ai

13,000 sq ft lb 19‐0‐7+Dimen A A

50 lbs 19‐0‐7 Dimension 0.19 lbs N 0.73 lbs N

13,000 sq ft lb 19‐0‐7+Dimen 1000 sq ft

Combination products are usually pretty close in lbs ai/A and lbs N/1000 when applied at label rates

Product lbs ai/A lbs N/1000

19‐3‐5 Barricade 0.375% 0.6 0.70

19‐3‐9 Barricade 0.375% 0.6 0.70

20‐0‐10 Barricade 0.287% 0.6 0.85

21‐3‐8 Barricade 0.426% 0.6 0.68

Granule size??

Big and heavy?Small and light?

Granular size effects on PRE crabgrass control

Sizeparticles/gram Barricade Dimension

23 43 66

58 71 75

165 74 75

465 81 84

1310 82 82

3728 83 75

10,606 83 82

(Mississippi State 1999)

Watering in PRE’s??

Yes?No?

Effect of watering‐in PRE’s applied very early May in 2011 in Mead, NE (UNL 2011).

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% Crabgrass control 15 July 2011

No waterWatered in

LSD=32Check=15% cover

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Effect of watering‐in PRE’s applied very early May 2012 in Mead, NE (UNL 2012).

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% Crabgrass control 15 July 2012

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LSD=20Check=65% cover

Liquid

GranuleRain/Irrigation

Soil solution (available)

Vapor(unavailable)

Fate of a Preemergence Herbicide

Soil colloids/thatch (unavailable)

Timing of PRE app??

Timing of PRE’s?

• “Apply 2 weeks prior to expected germination”

• “Crabgrass germinates when soil temperatures are above 50‐55oF for 5 days”

• “Apply when forsythia are blooming”• Better to apply early than late

Crabgrass control on July 15 from PRE’s applied on 6 different dates in fall/spring. (Averaged over three years, UNL 2013)

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Dimension 2EW 0.25 lbs ai

Barricade 4FL 0.38 lbs ai/A

Pendulum AQ 1.5 lbs ai/A

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Barricade 4 FL 0.75 lbs ai/A

Pendulum AQ 3.0 lbs ai/A

Crabgrass control on July 15 from PRE’s applied on 6 different dates in fall/spring. (Averaged over three years, UNL 2013) Sequential applications of PRE’s

• Most effective in tough crab areas • Generally ½ + ½ or ¾ + ½ (check label)• Previously thought that same ai should be used for both apps

August crabgrass cover after split apps of the same or different PRE’s averaged over 4 locations (UNL 2011)

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% Crabgrass cover (Aug)

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Changing ai for sequential

• More convenient• Maybe more economical• Expand the spectrum:Pendimethalin, prodiamine are a little better with summer annual broadleaves than dithiopyr

• Could use dithiopyr for the sequential (late May‐June) app regardless what or if PRE was applied in previous round to pick up germinating crabgrass in hotspots

Bottom line on PRE’s

• Thick turf• Water‐in/rain if possible• Don’t skimp on the rates• App timing is flexible (within reason and especially with sequential apps)

• Sequential apps improve control regardless of ai’s used

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POST emergence options

• Smaller the crabgrass, the more effective• Multiple apps may be needed for most effective and/or extended control

• Combine with PRE in early apps• Do not apply to moisture‐ or heat‐stressed turf

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Crabgrass Emergence on Round-up killed plots (applied 4 weeks prior to observation)

Aug 15 2008 seeding on Sept 15, 2008100% crabgrass cover

What could happen with a Sep application to “kill” crabgrass?


• Dithiopyr• Dimension plus other post‐patents

• Quinclorac• Drive plus other post‐patents• SquareOne (with carfentrazone)• Solitaire (with sulfentrazone)• Onetime (with MCPP & dicamba)• Q4 Plus (with sulfentrazone, 24D, & dicamba)

• Fenoxaprop• Acclaim• Last Call (with fluroxypyr and dicamba)

• Mesotrione• Tenacity

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• Untillered• Dithiopyr• Quinclorac

• Tillered (multiple apps most effective)• Quinclorac (usually)• Fenoxaprop• Mesotrione

Crabgrass options in cool‐season seedings

• Tenacity• PRE on bare soil• POST over turfed areas, 28 days after emergence

• Drive• POST 28 DAE

• SquareOne (Quinclorac+carfentrazone)• POST 7 DAE

• Dithiopyr • Early POST with residual• “…developed a good root system and a uniform stand, and have received at least two mowings”

KBG cover 6 weeks after emergence (UNL 2011)

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At Seeding 0 WAE 2 WAE Untreated

% KBG Cover 6 W

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Tenacity 8 fl oz/a Tupersan 12 lb/a

Drive XLR8 64 fl oz/a Square One 12 oz/a

Imprelis 4.5 fl oz/a Quicksilver 2.1 fl oz/a

LSD=19

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At Seeding 0 WAE 2 WAE Untreated

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Tenacity 8 fl oz/a Tupersan 12 lb/a

Drive XLR8 64 fl oz/a Square One 12 oz/a

Imprelis 4.5 fl oz/a Quicksilver 2.1 fl oz/a

TF cover 6 weeks after emergence (UNL 2011)

LSD=10

Crabgrass control in newly‐seeded buffalograss

• PRE: Tenacity in seedbed plus one or two apps starting 2‐4 weeks after emergence

• Post: 0‐4 weeks after emergence

– Drive XLR8

– SquareOne

– Tenacity

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Dismiss

Solitaire

Tenacity

Princep Caliber 90

Echelon

Xonerate

SquareOne

Drive XLR8

Quicksilver

Kerb SC T&O

Plateau

Barricade 4FL

Dismiss

Solitaire

Tenacity

Princep Caliber 90

Echelon

Xonerate

SquareOne

Drive XLR8

Quicksilver

Kerb SC T&O

Plateau

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Dismiss

Solitaire

Tenacity

Princep Caliber 90

Echelon

Xonerate

SquareOne

Drive XLR8

Quicksilver

Kerb SC T&O

Plateau

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% Cover at 6WAE (Bowie buffalograss/weeds)

2012 – Effect of single applications of herbicides over seedling buffalograss (UNL 2012) (primary weed was redroot pigweed)

Applied at seeding Applied 2WAE Applied 4WAE

Weed LSD = 14Turf LSD = 25



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Plateau

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Solitaire

Tenacity

Princep Caliber 90

Echelon

Xonerate

SquareOne

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Quicksilver

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Plateau

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Dismiss

Solitaire

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Princep Caliber 90

Echelon

Xonerate

SquareOne

Drive XLR8

Quicksilver

Kerb SC T&O

Plateau

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check

% Cover (Bowie buffalograss/w

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2013 ‐ Effect of single applications of herbicides over seedling buffalograss (UNL 2013) (primary weed was yellow foxtail)

Applied at seeding Applied 2WAE Applied 4WAE




Life cycles

• Perennials• Germinates anytime and will persist for years

• Summer annuals• Germinates in spring, sets seed in summer and dies with frost

• Winter annuals• Germinates in fall, sets seed in spring and dies with summer heat

• Biennials• Germinates anytime, stays as a rosette the first year, bolts, sets seed, and dies in second year

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Postemergence ai’s

• 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)• clopyralid (Lontrel)• fluroxypyr (Spotlight)• quinclorac (Drive)• metsulfuron methyl (Manor)• mesotrione (Tenacity) • halosulfuron (Sedgehammer)• carfentrazone‐ethyl (Quicksilver, Speed Zone, Power Zone)• sulfentrazone (Surge, Q4, Dismiss)• penoxalum (LockUp)

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Preemergence ai’s

• Isoxaben– Gallery (Snapshot)– Isoxaben

Broadleaf weed control

• Sep‐Nov is best!!–Controls most life cyles–Moves with photosynthate to the roots as weeds prepare for winter

– Fewer ornamentals to damage–Allows turf to fill in holes left by weeds–Early apps less effective than late apps

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Application Date (1986)

Fall broadleaf weed control on various application dates, rated in the fall and following spring. (Michigan State Univ. 1988) Three‐year mean of ground ivy control in June from herbicides

applied on various dates the previous fall (Purdue 2007).

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Application Date Speed Zone 3 ptSpeed Zone w/o carf. 3 ptsTurflon 2 ptsTurflon 2 pts + Gallery 1.33 lbsVista 1.33 pts

Minimize spring broadleaf control

• High risk of damage to trees, shrubs, ornamentals, vineyards, etc.

• Direct exposure with drift in high winds• Volatilization and off‐site movement• Difficult to prove cause but blanket blame is on turf industry professionals and DIYs

Damage pix Damage pix

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Damage pix Broadleaf weed control‐ spring

• Ester formulations work better in cool weather• But are more expensive and more volatile leading to more offsite movement

• A few weeks before or after flowering in spring is better than at flowering

• No earlier with traditional chemistry

Effect of spring application timing of 24D ester on dandelion control in June (Purdue 1992)

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% control (June)

Application week

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Effect of spring application timing of 24D amine on dandelion control in June (Purdue 1992)

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Broadleaf weed control‐ spring

• 150 GDD50 for ester formulations• 225+ GDD50 for amines• Dow’s Defendor can be applied in Fall or March‐April to limit dandelions, etc.• Useful on new accounts• Useful on schools, etc. that prefer not to use phenoxies


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Summer annuals

• Knotweed, purslane, oxalis, etc.

• Most problematic in thin turf next to walks, drives, cart paths, etc.

• Often germinate early and continue to germinate into summer

• Single app of Gallery (isoxaben)

• Multiple apps of POST

Percent control of prostrate knotweed from applications made 20 May 2014 (UNL 2014)

4 June 18 July

Trimec Classic 3 pt/A24D + MCPA + dicamba

65 a 70 ab

Trimec Classic 4 pt/A24D + MCPA + dicamba

64 a 61 b

Escalade2 2.5 pt/A24D + fluroxpyr + dicamba

80 a 97 a

Untreated (actual cover)

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0 c(97)

Yellow nutsedge• Germinates from tubers in early summer• Spreads via rhizomes throughout summer• Dies with frost• Tubers can lie dormant for many years• Tubers will regerminate multiple times if young plants are killed

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Yellow nutsedge pix

Yellow nutsedge pix Yellow nutsedge pix

Yellow nutsedge pix

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Yellow nutsedge• Basagran, Sedgehammer, Certainty, or Dismiss at best starting in late May‐June

• Early applications may trigger regermination of tubers

• Multiple apps are most effective• “Preemergence” doesn’t work• Eschelon (Dismiss + Prodiamine) at traditional crabgrass timing (early May)?

Control of yellow nutsedge with Sedgehammer or Dismiss applied on 3 June or 15 July, 2013.

% Control

Rate/1000 App date 9/17/2013 6/6/2014

Sedgehammer 0.03 oz June 3 90 ab 97 a

Sedgehammer 0.03 oz July 15 93 ab 55 bc

Sedgehammer 0.03 oz June 3+July15 97 a 94 aDismiss 0.12 fl oz June 3 21 cd 36 cdDismiss 0.12 fl oz July 15 16 cd 9 deDismiss 0.12 fl oz June 3+July15 33 c 40 cSedgehammer 0.03 oz June 3 97 a 98 a

Dismiss 0.12 fl oz July 15

Dismiss 0.12 fl oz June 3 67 b 72 ab

Sedgehammer 0.03 oz July 15Untreated Check 0(32%) d 0(37%) e

Control of yellow nutsedge with Sedgehammer or Dismiss applied on 3 June or 15 July, 2013.

% Control

Rate/1000 App date 9/17/2013 6/6/2014

Sedgehammer 0.03 oz June 3 90 ab 97 a

Sedgehammer 0.03 oz July 15 93 ab 55 bc

Sedgehammer 0.03 oz June 3+July15 97 a 94 aDismiss 0.12 fl oz June 3 21 cd 36 cdDismiss 0.12 fl oz July 15 16 cd 9 deDismiss 0.12 fl oz June 3+July15 33 c 40 cSedgehammer 0.03 oz June 3 97 a 98 a


Dismiss 0.12 fl oz June 3 67 b 72 ab

Sedgehammer 0.03 oz July 15Untreated Check 0(32%) d 0(37%) e

Control of yellow nutsedge with Sedgehammer or Dismiss applied on 6 June or 17 July, 2014

% control

Rate/1000 App date 9/17/2014

Sedgehammer 0.03 oz June 3 100 a

Sedgehammer 0.03 oz July 15 17 c

Sedgehammer 0.03 oz June 3+July15 99 aDismiss 0.12 fl oz June 3 63 bDismiss 0.12 fl oz July 15 11 cDismiss 0.12 fl oz June 3+July15 85 abSedgehammer 0.03 oz June 3 99 a


Dismiss 0.12 fl oz June 3 75 ab

Sedgehammer 0.03 oz July 15Untreated Check 0(50%)c

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Perennial grasses

• Difficult to control a perennial grass in a perennial grass

• May not be worth the effort

• Creeping bentgrass, nimblewill, windmill, smooth brome

– 3 apps of Tenacity/year

• Zoysia/bermudagrass

– 5 apps of Roundup starting after green up and every 2‐3 weeks until reseeding in the fall

– repeat in 5 years

Pylex

• Controls bermudagrass in cool‐season grasses when combined with triclopyr, 3 apps 2 3‐4 weeks intervals starting in June

• Controls nimblewill in cool‐season grasses when combined with triclopyr, 3 apps 2 3‐4 weeks intervals starting in June

• Also controls goosegrass

Zac Reicher

http://turf.unl.edu/

[email protected]

ne turf conference turf fundamemtals weed control · 3 after 3rd2,4-d app and regrowth effect of...

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