Turf essentials: Lawn weed control

Transcription

1 Turf essentials: Lawn weed control Zac Reicher 1

2 Cultural practices for thick turf Highest mowing height Mow frequently Reduce irrigation Fertilize primarily in the fall Manage traffic/compaction Managing resistance 2,4-D susceptible Maximize cultural controls Use high label rates Alternate modes of action 2,4-D tolerant After 2,4-D app and regrowth After 2 nd 2,4-D app and regrowth 2

3 After 3 rd 2,4-D app and regrowth % crabgrass cover Range tee Adjacent rough 1 app 2 app Quin 75 DF Quin 75 DF Quin 75 DF Quin 75 DF Quin XLR8 Mezo.25 lbs Untreated.75 lbs ai/a.75 lbs ai/a 1.5 lbs ai/a 2.25 lbs ai/a.75 lbs ai/a ai/a w/o NIS Effect of Drive or Tenacity on lateseason crabgrass in a driving range tee and adjacent golf course rough. Initial applications made on 25 Aug 8 and MSO included at 1.5 pts/a on all Drive apps other than where stated (Purdue 8). Crabgrass Summer annual Germinates in spring Sets seed in summer Dies with frost Can produce 15 tillers and 15, seeds per plant 1, seeds/plant X % viable = germinating seeds germinating seeds X 95% control = 5 plants where 1 was last summer 3

4 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. % Crabgrass control in August Effect of formulation and rate of Dimension on crabgrass control over two years (UNL, 14) (apps made late Apr fb late June) EW WSP c cd e c bc ab de ab ab a a a a ab a ab ab ab ab ab lbs AI/Acre PRE/fertilizer combos Watch the N rate! Increase slow release % with rates >.7 lbs N/ Most cool season lawns require little N in spring Cannot reduce N rate without reducing PRE rate Granule size 4

5 Combination products are usually pretty close in lbs ai/a and lbs N/ when applied at label rates Product lbs ai/a lbs N/ Barricade.375% Barricade.375%.6.7 Barricade.287% lbs with.15% Dimension 5 lbs covers 13, sq ft 5 lbs 19 7 Dimension.15 lbs ai 43,56 sq ft.25 lbs ai 13, sq ft lb 19 7+Dimen A A 5 lbs 19 7 Dimension.19 lbs N.73 lbs N 13, sq ft lb 19 7+Dimen sq ft Barricade.426%.6.68 Granular size effects on PRE crabgrass control Granule size?? Big and heavy? Small and light? Size particles/gram 23 Barricade 43 Dimension , (Mississippi State 1999) Watering in PRE s?? Yes? No? Effect of watering in PRE s applied very early May in 11 in Mead, NE (UNL 11). % Crabgrass control 15 July No water Watered in LSD=32 Check=15% cover 5

6 Effect of watering in PRE s applied very early May 12 in Mead, NE (UNL 12). % Crabgrass control 15 July No water Watered in LSD= Check=65% cover Fate of a Preemergence Herbicide Granule Rain/Irrigation Liquid Vapor (unavailable) Soil solution (available) 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 5 55 o F for 5 days Apply when forsythia are blooming Better to apply early than late % Control (July following app) Crabgrass control on July 15 from PRE s applied on 6 different dates in fall/spring. (Averaged over three years, UNL 13) Dimension 2EW.25 lbs ai Barricade 4FL.38 lbs ai/a Pendulum AQ 1.5 lbs ai/a October November March April May June 6

7 Crabgrass control on July 15 from PRE s applied on 6 different dates in fall/spring. (Averaged over three years, UNL 13) % Control (July following app) Dimension 2EW.5 lbs ai Barricade 4 FL.75 lbs ai/a Pendulum AQ 3. lbs ai/a 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 October November March April May June % Crabgrass cover (Aug) August crabgrass cover after split apps of the same or different PRE s averaged over 4 locations (UNL 11) c a a a a e f de cd b b a a a a a 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 7

8 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 Crabgrass Emergence on Round-up killed plots (applied 4 weeks prior to observation) 9 # crabgrass plants/25 sq ft Apr 1-M ay 15-M ay 1-Jun 15-Jun 1-Jul 15-Jul 1-Aug 15-Aug 1-Sep 15-Sep 1-Oct 15-Oct Aug 15 8 seeding on Sept 15, 8 % crabgrass cover What could happen with a Sep application to kill crabgrass? POST emergence options 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 8

9 POST emergence options Untillered Dithiopyr Quinclorac Tillered (multiple apps most effective) Quinclorac (usually) Fenoxaprop Mesotrione Crabgrass options in cool season seedings KBG cover 6 weeks after emergence (UNL 11) 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 WAE 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 At Seeding WAE 2 WAE Untreated TF cover 6 weeks after emergence (UNL 11) Crabgrass control in newly seeded buffalograss % TF Cover 6 WAE Tenacity 8 fl oz/a Drive XLR8 64 fl oz/a Imprelis 4.5 fl oz/a Tupersan 12 lb/a Square One 12 oz/a Quicksilver 2.1 fl oz/a LSD= PRE: Tenacity in seedbed plus one or two apps starting 2 4 weeks after emergence Post: 4 weeks after emergence Drive XLR8 SquareOne Tenacity At Seeding WAE 2 WAE Untreated 9

10 12 Effect of single applications of herbicides over seedling buffalograss (UNL 12) (primary weed was redroot pigweed) 13 Effect of single applications of herbicides over seedling buffalograss (UNL 13) (primary weed was yellow foxtail) 9 9 % Cover at 6WAE (Bowie buffalograss/weeds) Weed LSD = 14 Weed LSD = 5 Weed LSD = 6 Turf LSD = 25 Turf LSD = 22 Turf LSD = 24 Applied at seeding Applied 2WAE Applied 4WAE Dismiss Solitaire Tenacity Princep Caliber 9 Echelon Xonerate SquareOne Drive XLR8 Quicksilver Kerb SC T&O Plateau Barricade 4FL Dismiss Solitaire Tenacity Princep Caliber 9 Echelon Xonerate SquareOne Drive XLR8 Quicksilver Kerb SC T&O Plateau Barricade 4FL Dismiss Solitaire Tenacity Princep Caliber 9 Echelon Xonerate SquareOne Drive XLR8 Quicksilver Kerb SC T&O Plateau Barricade 4FL Untreated check % Cover (Bowie buffalograss/weeds) Weed LSD = 5 Weed LSD = 3 Weed LSD = 26 Turf LSD = 22 Turf LSD = Turf LSD = 13 Applied at seeding Applied 2WAE Applied 4WAE Dismiss Solitaire Tenacity Princep Caliber 9 Echelon Xonerate SquareOne Drive XLR8 Quicksilver Kerb SC T&O Plateau Barricade 4FL Dismiss Solitaire Tenacity Princep Caliber 9 Echelon Xonerate SquareOne Drive XLR8 Quicksilver Kerb SC T&O Plateau Barricade 4FL Dismiss Solitaire Tenacity Princep Caliber 9 Echelon Xonerate SquareOne Drive XLR8 Quicksilver Kerb SC T&O Plateau Barricade 4FL Untreated check 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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14 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) 14

15 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 15

16 Broadleaf Weed Control Fall broadleaf weed control on various application dates, rated in the fall and following spring. (Michigan State Univ. 1988) Sep 8-Oct 17-Oct 22-Oct 3-Oct 11-Nov Nov 86 Rating Application Date (1986) May 87 Rating % Control Three year mean of ground ivy control in June from herbicides applied on various dates the previous fall (Purdue 7) Sept 1 Sept 15 Oct 1 Oct 15 Nov 1 Nov 15 Speed Zone 3 pt Application Date Speed Zone w/o carf. 3 pts Turflon 2 pts Turflon 2 pts + Gallery 1.33 lbs Vista 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 16

17 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) % control (June) Mar 1 Mar 2 Mar 3 Mar 4 Apr 1 Apr 2 Apr 3 Apr 4 May 1 May 2 Application week % control (June) Effect of spring application timing of 24D amine on dandelion control in June (Purdue 1992) Mar 1 Mar 2 Mar 3 Mar 4 Apr 1 Apr 2 Apr 3 Apr 4 May 1 May 2 Application week Broadleaf weed control spring 15 GDD5 for ester formulations 225+ GDD5 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 Effect of spring application timing of 24D ester on dandelion control in June (Purdue 1992) % Control (June) GDD (5) 17

18 Effect of spring application timing of 24D ester on dandelion control in June (Purdue 1992) Summer annuals % Control (June) 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 GDD(5) Percent control of prostrate knotweed from applications made May 14 (UNL 14) Trimec Classic 3 pt/a 24D + MCPA + dicamba Trimec Classic 4 pt/a 24D + MCPA + dicamba Escalade2 2.5 pt/a 24D + fluroxpyr + dicamba Untreated (actual cover) 4 June 18 July 65 a 7 ab 64 a 61 b 8 a 97 a b (75) 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 18

19 Yellow nutsedge pix Yellow nutsedge pix Yellow nutsedge pix Yellow nutsedge pix 19

20 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, 13. % Control Rate/ App date 9/17/13 6/6/14 Sedgehammer.3 oz June 3 9 ab 97 a Sedgehammer.3 oz July ab 55 bc Sedgehammer.3 oz June 3+July15 97 a 94 a Dismiss.12 fl oz June 3 21 cd 36 cd Dismiss.12 fl oz July cd 9 de Dismiss.12 fl oz June 3+July15 33 c 4 c Sedgehammer.3 oz June 3 97 a 98 a Dismiss.12 fl oz July 15 Dismiss.12 fl oz June 3 67 b 72 ab Sedgehammer.3 oz July 15 Untreated Check (32%) d (37%) e Control of yellow nutsedge with Sedgehammer or Dismiss applied on 3 June or 15 July, 13. % Control Rate/ App date 9/17/13 6/6/14 Sedgehammer.3 oz June 3 9 ab 97 a Sedgehammer.3 oz July ab 55 bc Sedgehammer.3 oz June 3+July15 97 a 94 a Dismiss.12 fl oz June 3 21 cd 36 cd Dismiss.12 fl oz July cd 9 de Dismiss.12 fl oz June 3+July15 33 c 4 c Sedgehammer.3 oz June 3 97 a 98 a Dismiss.12 fl oz July 15 Dismiss.12 fl oz June 3 67 b 72 ab Sedgehammer.3 oz July 15 Untreated Check (32%) d (37%) e Control of yellow nutsedge with Sedgehammer or Dismiss applied on 6 June or 17 July, 14 % control Rate/ App date 9/17/14 Sedgehammer.3 oz June 3 a Sedgehammer.3 oz July c Sedgehammer.3 oz June 3+July15 99 a Dismiss.12 fl oz June 3 63 b Dismiss.12 fl oz July c Dismiss.12 fl oz June 3+July15 85 ab Sedgehammer.3 oz June 3 99 a Dismiss.12 fl oz July 15 Dismiss.12 fl oz June 3 75 ab Sedgehammer.3 oz July 15 Untreated Check (5%)c

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22 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 weeks intervals starting in June Controls nimblewill in cool season grasses when combined with triclopyr, 3 apps weeks intervals starting in June Also controls goosegrass Zac Reicher zreicher2@unl.edu 22