Advanced Weed Control for Athletic Field Turf
Transcription
Advanced Weed Control for Athletic Field Turf
1/9/2015 Advanced Weed Control for Athletic Field Turf Outline • • • • I. What is Properly Managed Turf? II. Preemergence Herbicides III. Postemergence Herbicides IV. Herbicide Resistance Management Gerald Henry, PhD – University of Georgia Jared Hoyle, PhD – Kansas State University Maintaining Healthy Turf • • • • • • Reduced Light Intensity Select the right turfgrass species/cultivar Proper irrigation Correct mowing height and frequency Adequate fertility Cultivation practices Using weeds as indicators Selecting the Right Grass Photo: Jim Brosnan, UT More than Herbicides Are Needed Here 1 1/9/2015 ‘TifGrand’ Hybrid Bermudagrass Hong Kong Gov. Stadium Use regional NTEP data Irrigation Irrigation • Amount: – Varies with grass species (rooting, etc.), soil type, and environmental conditions (evapotranspiration) • Frequency: – Varies with local conditions – Standard rule: apply water deeply and infrequently • Time of day: – Early morning hours are best ‐ evaporative loss is less and turf is allowed to dry Irrigation Frequency Mowing Frequent Infrequent and Deep 2 1/9/2015 Mowing Height • Each species has its mowing tolerance range • Below this range: – Turf will thin or be overtaken by weeds • Above this range: Above this range: – Increased disease pressure – Puffiness Clippings Mowing Frequency • Every 5 to 7 days • Lower height = ↑ frequency • Rules: – Never remove > 1/3 leaf / tissue per mowing – Avoid mid‐day mowing when heat stress occurs Effect of Mowing Height on Crabgrass • Contribute little to thatch • Can be safely returned if turf is mowed regularly • Returned clippings can contribute 2 lbs d li i ib 2 lb N/1000 ft2/year in addition to other nutrients • Clipping removal may reduce weed seed – Annual bluegrass Tall Fescue – 4 inch % Crabgras ss Cover Effect of Mowing Height on Crabgrass Incidence in Tall Fescue Hoyle et al. 2009 Tall Fescue – 1 inch 3 1/9/2015 Mowing to Reduce Weed Colonization • Mowing depletes carbohydrate reserves through biomass reduction • Mowing depletes carbohydrate reserves through biomass reduction Bahiagrass & Dallisgrass Mowing Heights (in.) 0.5, 2, 3, and non-mowed Henry et al. 2007 Rhizome Weight ((g) Mowing to Reduce Weed Colonization Bahiagrass Rhizome Weight (g) 350 300 250 0.5 inch 200 2.0 inch 150 3.0 inch 100 Non‐mowed 50 0 0.5 inch 2.0 inch 3.0 inch Non‐mowed N Fertility Programs • Cool‐season grasses (KBG) Fertility Cool‐Season N Program Timing Nitrogen (lb N/1000 ft2) March/April 0.5 – 0.75 May/June 0.5 – 0.75 June/July 0 August 1.0 September 1.0 Late Fall 1.0 – 1.5 – Rates will vary with environmental conditions and soil type – Lighter N applications in the spring – Heavier N applications in the fall – Minimize N applications in the summer – Fe can be applied for green up N Fertility Programs • Warm‐season grasses (Bermudagrass) – Rates will vary with environmental conditions and soil type – 1.0 lb N/1000 ft2 is recommended per growing month – No more than ½ lb N in September to minimize Spring Dead Spot 4 1/9/2015 Excessive Nitrogen Fertilization ↑ Shoot Growth Extensive Roots Cultivation Cultivation • Aerification/Verticutting • Alleviate thatch and soil compaction – Enhance rooting E h ti – Increase water infiltration – Increase gas exchange – Decrease nutrient deficiencies What are your weeds telling you? 5 1/9/2015 Weeds as Indicators • Soil Compaction – Associated with high traffic, poor water infiltration, etc. – Presence of prostrate knotweed, goosegrass, annual bluegrass, prostrate spurge, broadleaf plantain, khakiweed, etc. Weeds as Indicators • Low Soil Nitrogen Fertility – Associated with low fertility inputs, sandy soil, etc. – Presence of clover spp., black medic, common lespedeza, corn speedwell, hawkweed, etc. Weeds as Indicators • Wet/Saturated soils – Associated with poor water infiltration, heavy clay soils, low‐lying areas – Presence of sedge spp., annual bluegrass, goosegrass, mosses, etc. Photo: Pete Landschoot, PSU 6 1/9/2015 Weeds as Indicators • Low soil pH – red sorrel • High soil pH – plantains • Droughty soils – g y prostrate spurge, black p p g , medic, knotweed, yellow woodsorrel • High soil N – annual bluegrass, chickweeds, moss • Low mowing height – algae, annual bluegrass, moss, chickweeds Preemergence Herbicides Preemergence Herbicides Application Timing Summer Annuals Herbicides do not prevent weeds from germinating, they control weeds as they grow through the herbicide treated zone Spring Winter Annuals Summer Fall Winter Preemergence Weed Control • Target species: annual grasses; annual and some perennial broadleaf weeds • Spring applications – Initial app. late February to mid‐March I iti l l t F b t id M h – Sequential app. approx. 60 days later • Fall applications – Mid to late September Application Technique is Critical 7 1/9/2015 Preemergence Herbicides Large gaps in herbicide barriers result in weed escapes Preemergence Herbicides Preemergence Herbicides • More important than ever • Provide annual grassy weed control ‐ crabgrass, goosegrass, annual bluegrass, etc. • Preemergence herbicides: Herbicides do not prevent weeds from germinating, they control weeds as they grow through the herbicide treated zone – prodiamine (Barricade) – dithiopyr (Dimension) – pendimethalin (Pendulum) – oxadiazon (Ronstar) – oryzalin (Surflan)* *Not labeled for use on Kentucky bluegrass Specticle Launched in 2010 Active Ingredient – Indaziflam Chemical Class: Alkylazines Warm‐season Warm season turf tolerance turf tolerance Excellent activity on annual bluegrass, crabgrass spp., goosegrass, and broadleaf weeds • Low application rate • Long soil residual • Root absorbed only • • • • • 4.5 M 5.5 M UT – J. Brosnan 8 1/9/2015 Perennial Ryegrass Cover Specticle – Ryegrass overseeding Ryegrass overseeding safety – Recovery from wear/traffic, stress, and damage • Spring dead spot disease 32 WAIT % ryegrass co over • Not a good fit for Athletic Field turf! • Long soil residual/”root pruning” damage WAIT = Weeks After Initial Treatment Specticle DNA Herbicides Photo: J. Brosnan, UT Preemergence Herbicides • Dinitroanalines (DNAs): – Prodiamine (Barricade, Quali‐Pro Prodiamine) – Oryzalin (Surflan, Quali (Surflan, Quali‐Pro Pro Oryzalin) Oryzalin)* – Pendimethalin (Pendulum, Pre‐M, etc.) – Oryzalin + benefin (XL)* Rooting/Recovery Concerns “Root Pruning” Damage • Warm‐season turf issue – stoloniferous grasses • Herbicides are predominantly root absorbed *Not labeled for use on Kentucky bluegrass Photo: J. Brosnan, U Tenn 9 1/9/2015 Photo – A. Patton Preemergence Herbicides • Oxadiazon (Ronstar, Quali‐Pro Oxadiazon)* • Predominantly shoot absorbed • Dithiopyr (Dimension, Quali‐Pro Dithiopyr) • May cause similar damage to roots as DNA herbicides *Can be applied safely in the Spring to grasses seeded in the Fall Swollen roots on a bermudagrass stolon growing into soil where a preemergence herbicide was applied Bermudagrass Recovery from Spring Dead Spot in from Spring Dead Spot in Response to Preemergence Herbicides % SDS Reco overy Bermudagrass Recovery ‐ 2012 Recovery from 4/10 to 6/25 Untreated Check 6/25/2012 Ronstar ‐ Oxadiazon 6/25/2012 10 1/9/2015 Specticle ‐ Indaziflam Tower Active Ingredient – Dimethenamid Safe on warm and cool‐season turf Use on established turf Preemergence broadleaf, grass, and sedge weed control • Predominantly shoot absorbed • Freehand* = dimethenamid + pendimethalin • • • • 6/25/2012 *No cool‐season turf tolerance Large Crabgrass Control – 21 WAIT Pendulum – 4.2 pt/A % Crabgrass Cover fb Tower – 32 fl oz/A 80 Untreated Check 70 Pendulum fb Tower 60 Tower fb Tower 50 Tower fb Tower fb Tower fb fb 40 Freehand fb Freehand ‐ low Freehand fb Freehand ‐ high Drive + Tower 30 20 10 Barricade fb Barricade 0 Herbicide Treatments Sept. 15, 2011 Generic vs. Name Brand Preemergence Large Crabgrass Control % Contrrol 5 MAIT 100 80 60 40 20 0 Annual Grass Weed Control Annual Grass Weed Control 11 1/9/2015 Crabgrass/Goosegrass Control • Apply preemergence herbicides in the spring when daytime temperatures reach 65 F for four or more days • Materials must be watered in (1/2 inch) Materials must be watered in (1/2 inch) within 7 days after treatment in order to activate the herbicides Kentucky Bluegrass Preemergence Herbicides • • • • • • • • Benefin (Balan) Benefin + Trifluralin (Team Pro) Dithiopyr (Dimension) Mesotrione (Tenacity) – crabgrass only Oxadiazon (Ronstar) Pendimethalin (Pendulum) Prodiamine (Barricade) Siduron (Tupersan) Non‐overseeded Bermudagrass • • • • • • • • • • • Benefin (Balan) Preemergence Benefin + Oryzalin (XL) Herbicides Benefin + Trifluralin (Team Pro) Bensulide (Bensumec) g / g Bensulide + Oxadiazon ((Scott’s Goosegrass/Crabgrass Control) Dithiopyr (Dimension) Metolachlor (Pennant) Oryzalin (Surflan) Oxadiazon (Ronstar) Pendimethalin (Pendulum) Prodiamine (Barricade) Annual Bluegrass Control • Apply in late summer – August/September • Materials must be watered in (1/2 inch) within 7 days after treatment in order to activate the herbicides activate the herbicides • Most herbicides labeled for preemergence control of crabgrass/goosegrass effectively control annual bluegrass Preemergence Herbicides Annual Grass Control in Overseeded Bermudagrass • Balan 2.5G (benefin) – 120 lbs/A –6 to 8 WBO fb 6 WAO • Dimension 40WP (dithiopyr) – ( py ) 1.25 lbs/A / –8 WBO • Barricade 65WG (prodiamine) – 0.38 to 0.75 lbs/A –8 WBO fb 4 WAO 12 1/9/2015 Preemergence Herbicides • Pendulum 60 WDG (pendimethalin) – 3.4 lbs/A –12 WBO • Ronstar 2G (oxadiazon) – 100 lbs/A –16 WBO Postemergence Herbicides Only Provide Fair Control New Chemistries Celsius • Formulation: 68 WG • Active Ingredients: – Thiencarbazone – Iodosulfuron – Dicamba • Rate: 2.5 to 7.4 oz/A • Tolerant Turf Species: bermudagrass • Target Weeds: POST annual and perennial broadleaf weeds and grasses Carpetgrass Control % Conttrol % Control Virginia Buttonweed Control Initial apps. made in July Initial apps. made in July 13 1/9/2015 Dallisgrass Control – 37 WAIT Tribute Total Rating - June 2011 – Thiencarbazone – Foramsulfuron – Halosulfuron • Rate: 3.2 oz/A • Tolerant Turf Species: bermudagrass • Target Weeds: POST sedge, broadleaf weeds, cool‐season grasses, large crabgrass, goosegrass, dallisgrass % Controll • Formulation: 60.5 WG • Active Ingredients: Tribute Total – 3.2 oz/A – Sept – 37 WAIT Tropical Signalgrass Control Spot Spray App. # % Control May 5th June 9th 94 96 3 3x 98 96 4x 100 98 5x 100 100 2x Trts: Sept. 23; Oct. 7, 21; and Nov. 4 and/or 18. – 0.073 oz Tribute Total/gal water 6/6/2011 McCarty and Estes – GCM Magazine, Sept. 2014 Tribute Total Overseeding Safety Tribute Total Overseeding Safety • Tribute Total – 3.2 oz/A – Applied 8, 6, 4, and 2 WBO • Perennial ryegrass overseeding – 8 lbs/1000 ft2 – Oct. • Evaluated ryegrass cover in mid‐December 14 1/9/2015 Ryegrass Overseeding Safety Blindside % Ryegrasss Cover • Formulation: 66 WG • Active Ingredients: – Sulfentrazone – Metsulfuron • Rate: 3.25 to 10 oz/A • Tolerant Turf Species: bermudagrass and Kentucky bluegrass • Target Weeds: POST grasses, sedges, and broadleaf weeds Ground Ivy Control Khakiweed Control Blindside – 8 WAT Blindside – 12 WAIT SquareOne • Launched in 2011 • Active Ingredients: – Carfentrazone – Quinclorac Q i l • Rate: 8 to 18 oz/A • Tolerant Turf Species: bermudagrass, Kentucky bluegrass, perennial ryegrass • Broadleaf, sedge, and grassy weed control • Fast activity Defendor • Launched in 2013 • Active Ingredient: – florasulam • Turf Tolerant Species: bermudagrass, p g , Kentucky bluegrass, perennial ryegrass, tall fescue • Target Weeds: annual and perennial blws • Defendor packaged with Dimension 2EW for early spring dandelion control (Purdue) 15 1/9/2015 Symptomology from florasulam Purdue University – April 2, 2012 Photo: A. Patton, Purdue Photo: A. Patton, Purdue Dimension 2EW + florasulam applied March 16 Dandelion Control Photo: A. Patton, Purdue 40 a % Dandelion cover 35 ab 30 25 20 15 10 abc cd cd e de e e 5 0 100% bloom reduction when applied 2 wks before flowering Defendor Use Tips • Early application at least 2 weeks prior to bloom • Sequential applications to improve control • Best results l – follow first application of Dimension + Defendor with a broadleaf herbicide (like Triplet or Trimec) after regrowth A. Patton, Purdue Defendor Summary • Fall BDLV herbicide apps work well to control perennials • Defendor does something unique ‐ keeps dandelions from flowering when applied in early spring • Timing is early with spring PRE herbicides as a tank‐mix g g targeted for crabgrass control • Defendor’s strength is early season “control” and bloom suppression • Utility in LCO market – Reduces call‐backs – Will delay application of phenoxy herbicides in spring until better conditions for control exist 16 1/9/2015 Bleaching Pylex • Greatest bleaching observed during active turfgrass growth periods – spring and fall for cool‐season turf. Less bleaching seen during summer months when turf is growing less • Addition of Turflon® ester and Drive® XLR8 herbicide to Pylex results in a significant reduction in bleaching • The addition of Turflon and Drive XLR8 act to slow down growth of the target weed resulting in less bleaching • Launched in 2013 • Active Ingredient: – Topramazone • Bleaching herbicide (HPPD inhibitor) • Turf Turf Tolerant Species: Tolerant Species: Kentucky bluegrass, Kentucky bluegrass, perennial ryegrass, tall fescue • Bermudagrass and goosegrass control in cool‐ season turf • Spot spray only for athletic fields – 1 to 1.5 fl oz/A 98 Tompramazone (14 DAA) Not Treated Pylex Turflon Pylex + Turflon Goosegrass control: Trts made on July 21 and August 11 to tillered goosegrass. VT, 2012 Uses • Bermudagrass control – multiple apps required late summer with Turflon (triclopyr) 100 90 • Goosegrass control 80 70 % Controll – tank mix with Drive® or Onetime® to enhance crabgrass control • Nimblewill or crabgrass control – Pendulum® can be tank mixed for residual crabgrass control • Weed control at time of seeding Pylex herbicide 1.5 oz 2 app 60 50 Pylex herbicide 1.5 + Turflon 32 oz 2 app 40 30 Tenacity 8 oz 2 app 20 10 0 1‐Aug 101 1‐Sep 102 17 1/9/2015 Comparing Pylex vs. Tenacity • Pylex herbicide • Tenacity herbicide – Very good on bermudagrass – Excellent on goosegrass – Better on dandelion – Weaker on bermudagrass and g goosegrass g – Safer to more grasses – No spot spray restriction – Poa annua is sensitive – Moderate activity on nutsedge Difficult to Control Weeds Difficult to Control Weeds • Similar on most broadleaves • Similar on crabgrass and nimblewill Controlling Sedge Spp. Controlling Sedge Spp. Yellow Nutsedge Yellow Nutsedge Yellow Nutsedge Yellow Nutsedge • Postemergence Herbicide Options: – Halosulfuron (Sedgehammer) • Safe on bermudagrass, Kentucky bluegrass, and perennial ryegrass and perennial ryegrass – Imazaquin (Image) • Safe on bermudagrass – Sulfosulfuron (Certainty) • Safe on bermudagrass • Postemergence Herbicide Options: – Trifloxysulfuron (Monument) • Safe on bermudagrass – Bentazon (Basagran) ( ) • Safe on bermudagrass, Kentucky bluegrass, and perennial ryegrass – Sulfentrazone (Dismiss) • Safe on bermudagrass, Kentucky bluegrass, and perennial ryegrass 18 1/9/2015 Yellow Nutsedge • Postemergence Herbicide Options: – Sulfentrazone + Imazethapyr (Dismiss South) Yellow Nutsedge Control in Bermudagrass • Treatments: – Sedgehammer (1.3 oz/A) applied once or twice – MSMA (1 oz/1000 ft2) applied once – MSMA (1 oz/1000 ft MSMA (1 oz/1000 ft2) + Image (1.3 pt/A) applied ) + Image (1 3 pt/A) applied once – Monument (0.53 oz/A) applied once or twice • Safe on bermudagrass – Mesotrione (Tenacity) ( ) • Safe on Kentucky bluegrass and perennial ryegrass Yellow Nutsedge Control in Bermudagrass % control Yellow Nutsedge Control in Bermudagrass Application dates: May 13, May 26 (MSMA), and Jun 23 Application Timings: July 15, 2009 and August 12, 2009 Sulfentrazone 4 WAT – Aug 4 Purple Nutsedge p g 19 1/9/2015 Purple Nutsedge Purple Nutsedge • Tubers linked by chains of rhizomes • Postemergence Herbicide Options: – Trifloxysulfuron (Monument) • Safe on bermudagrass – Sulfosulfuron (Certainty) ( ) • Safe on bermudagrass – Sulfentrazone + Imazethapyr (Dismiss South) • Safe on bermudagrass Purple Nutsedge • Postemergence Herbicide Options: – Imazaquin (Image) Purple Nutsedge Control in Common Bermudagrass fl oz or oz/A • Safety on bermudagrass – Sulfentrazone (Dismiss) • Safe on bermudagrass, Kentucky bluegrass, and perennial ryegrass – Halosulfuron (Sedgehammer) • Safe on bermudagrass, Kentucky bluegrass, and perennial ryegrass WAIT = Weeks After Initial Treatment Certainty – 12 WAIT Dismiss South – 12 WAIT 20 1/9/2015 Purple Nutsedge Control with Dismiss Dallisgrass Application date: 6/15/2008 Dallisgrass Control ‐ TX • September Application – Tribute Total – 2 or 3.2 oz/A + MSO + AMS • October Application – Tribute Total Tribute Total – 2 or 3.2 oz/A + MSO + AMS 2 or 3 2 oz/A + MSO + AMS • Sept fb Oct Application Results – 37 WAIT Results 37 WAIT – Tribute Total – 2 or 3.2 oz/A + MSO + AMS – Foramsulfuron – 64 fl oz/A – Dicamba + Iodosulfuron + Thiencarbazone (Celsius) – 3.6 oz/A + foramsulfuron – 64 fl oz/A Dallisgrass Control – 37 WAIT Untreated Check – 37 WAIT % Controll Rating - June 2011 6/6/2011 21 1/9/2015 Tribute Total – 3.2 oz/A – Sept – 37 WAIT Tribute Total – 3.2 oz/A ‐ Oct – 37 WAIT 6/6/2011 6/6/2011 Cultural + Chemical Control Dallisgrass Control • Initial app. – June 14, 2013 • Sequential app. – Aug. 28, 2013 • Herbicide treatments (app. to verticut and non‐verticut): i ) • Location: Pine Hills GC, Winder, GA • Trial site was mowed 48 hrs before study initiation • Half the site was verticut two directions – 1 in. depth • Entire area was raked of debris – – – – Dallisgrass Control – 8 WAIT Before % Conttrol 2nd App. Tribute Total – 3.2 oz/A Celsius – 3.6 oz/A + Revolver – 64 fl oz/A MSMA – 44 fl oz/A Certainty – 1.25 oz/A + MSMA – 44 fl oz/A Dallisgrass Control with Pylex • Option A: – 3 apps. (1 to 1.3 fl oz/A) 3 ‐ 4 weeks apart – 1st app. mid‐to‐late summer • Option B: – 2 apps. (1.5 fl oz/A) 3 ‐ 4 weeks apart – 1st app. late summer Initial apps. made in June 22 1/9/2015 Crabgrass/Goosegrass • Typically apply during the months of June and July Crabgrass/Goosegrass – Sequential applications may be necessary • Target immature plants Target immature plants – Especially important with goosegrass control Crabgrass/Goosegrass Control • Postemergence Herbicide Options: – Quinclorac (Drive XLR8) – crabgrass only • Safe on bermudagrass, Kentucky bluegrass, and perennial ryegrass • Can be applied at overseeding and 28 days after • Formulated mixtures – – – – – Crabgrass/Goosegrass Control • Postemergence Herbicide Options: – Fenoxaprop (Acclaim Extra) • Safe on Kentucky bluegrass quinclorac + sulfentrazone (Solitaire) quinclorac + sulfentrazone + 2,4‐D + dicamba (Q4 Plus) quinclorac + 2,4‐D + dicamba (Quincept) quinclorac + dicamba + MCPP (Onetime) quinclorac + carfentrazone (Square One) Mature Large Crabgrass ‐ UGA • Application time – July 16, 2012 • Site – mature large crabgrass (multi crabgrass (multi‐ tillered) maintained at 2 inches 23 1/9/2015 Herbicide Treatments Untreated Check – 4 WAT • Drive XLR8 (64 fl oz/A) + MSO (0.5% v/v) • Tribute Total (3.2 oz/A) + MSO • Acclaim Extra (13 oz/A) + NIS (0.25% v/v) + Dimension (0.5 pts/A) i i (0 /A) • Acclaim Extra (20 oz/A) + NIS + Dimension (0.25 pts/A) • Acclaim Extra (28 oz/A) + NIS Drive XLR8 + MSO – 4 WAT 64 fl oz/A Crabgrass/Goosegrass Control • Postemergence Herbicide Options: – Mesotrione (Tenacity) • Safe on dormant bermudagrass, Kentucky bluegrass, and perennial ryegrass – Topramezone (Pylex) • Safe on Kentucky bluegrass and perennial ryegrass • Spot spray at 1 to 1.5 fl oz/A Tribute Total + MSO – 4 WAT 3.2 oz/A Crabgrass/Goosegrass Control • Postemergence Herbicide Options: – Prodiamine + Sulfentrazone (Echelon) • Safe on bermudagrass, Kentucky bluegrass, and perennial ryegrass • Early POST control of seedling crabgrass but mainly PRE activity – Foramsulfuron (Revolver) – goosegrass only • Safe on bermudagrass 24 1/9/2015 Khakiweed % Conttrol Sequential Apps. for Khakiweed Control 100 90 80 70 60 50 40 30 20 10 0 Speedzone Southern (1x) Celsius 4Speed XT Imprelis Initial app. – 6/1/2010 Pend Aquacap + Onetime d i Pend + BAS 8004H Pend + Drive XLR8 Blade 0.5 oz Blade 1.0 oz Monument 0.35 oz 8 WAIT Monument 0.53 oz Sequential apps. made 3 to 5 WAIT Blade – 0.5 oz/A – 8 WAIT Monument – 0.35 oz/A – 8 WAIT Celsius – 0.085 oz/1000 ft2 – 8 WAIT 4Speed XT – 1.1 fl oz/1000 ft2 – 8 WAIT 25 1/9/2015 Annual Bluegrass Control in Overseeded Bermudagrass • Postemergence Herbicide Options: – Foramsulfuron (Revolver) • Apply up to 1 week before overseeding – Rimsulfuron (TranXit) • Apply up to 10 to 14 days before overseeding Annual Bluegrass Control in Overseeded Bermudagrass • Postemergence Herbicide Options: – Flazasulfuron (Katana) • Apply up to 2 to 4 weeks before overseeding • Control enhanced with addition of urea – Trifloxysulfuron (Monument) • Apply up to 3 weeks before overseeding Annual Bluegrass Control in Overseeded Bermudagrass • Postemergence Herbicide Options: – Ethofumesate (Prograss) • Two apps. in late fall to early winter after overseeding di • 1st app. late November with a sequential 3 weeks later Herbicide Resistance Management – Bispyribac Sodium (Velocity) • Two apps. in the spring after overseeding in fall • 1st app. in late winter/early spring Photo: J. Brosnan ‐ UT What is herbicide resistance? • “The ability of a plant to survive and reproduce following exposure to a dose of herbicide normally lethal to the wild type” Vencill et al. 2012. Weed Science 26 1/9/2015 Understanding Resistance • Weeds do not change or mutate to become resistant • A few weeds may survive exposure to an herbicide due to their genetic makeup herbicide due to their genetic makeup • When those weeds that survive breed, some of their offspring will inherit the genetic trait that confers resistance Understanding Resistance • These weeds will not be affected the next time a similar herbicide is used • If the same herbicide is applied often, the proportion of less susceptible individuals in proportion of less‐susceptible individuals in the population will increase Understanding Resistance • Higher rates and more frequent applications of the herbicide are often used until eventually the pesticide provides little or no control • At this point, the population has become resistant…. Why does it happen? • • • • • Herbicide tolerant cropping systems Lack of diversified weed management Same Modes of Action (MOA) Lack of cultural weed management Weeds have short life cycles, wide geographic ranges, and large populations – Substantial genetic diversity Why does it matter? Herbicide Resistance • Increased cost to control weeds • Lost revenue • Lost herbicidal MOAs 27 1/9/2015 Case Studies Case Studies Dr. Jim Brosnan, UT Dinitroanaline Resistance • Cases of DNA resistance reported in NC and TN • Two new reports in TN in spring of 2012 Prodiamine (Barricade) • • • • Dinitroaniline (DNA) Mitotic inhibitor Root absorbed/active / Used for PRE control of annual grasses and some broadleaf weeds Lambert Acres Golf Club • Maryville‐Alcoa, TN • Roundup (32 fl oz/A) + Barricade (0.75 lb ai/A) • Applied for 10 consecutive years • No annual bluegrass control reported in 2011 Root growth of prodiamine resistant (PR) and susceptible (SS) annual bluegrass in Alcoa, TN 0 0.41 4.1 41 410 4100 28 1/9/2015 Biotype is Cross-Resistant to Glyphosate DNAs = Seedling Root Inhibitors Susceptible Resistant Prodiamine Resistant Goosegrass Resistant Root growth after prodiamine at 1.0 mM Root growth after prodiamine at 0.001mM Susceptible Root growth after prodiamine at 1.0 mM 29 1/9/2015 What is effective on mature goosegrass POST? J.T. Brosnan, Ph.D. University of Tennessee PR Goosegrass Control with Pylex • • • • • • Topramezone HPPD inhibitor J.T. Brosnan, Ph.D. Grassy weed control University of Tennessee Cool-season grasses Rates of 0.5 to 2.0 fl oz/A with MSO surfactant Yearly max at 4 fl oz/A Goosegrass Co ontrol (%) Pylex Multi‐tillered Plants 100 Pylex+MSO (0.5 fl oz) Pylex+MSO (0.75 fl oz) Pylex+MSO (1 fl oz) Revolver (17.4 fl oz) Revolver (26.2 fl oz) 75 50 25 0 14 DAT 28 DAT 50 DAT Untreated Check Pylex (1 fl oz) + MSO ‐ 50 DAT Bermudagrass Injury Quicker Recovery with Late Summer Apps Late Summer Apps. J.T. Brosnan, Ph.D. University of Tennessee 30 1/9/2015 Options? It’s not just g a single product • Oxadiazon program • Increased $$ • What do you rotate to from oxadiazon? p • No post winter annual • Tank mix with glufosinate? (access, $$) • Specticle program • Increased $$ • Rotation with oxadiazon? • Traffic recovery issues? Options? • ALS or Simazine Programs • $$ • No residual for summer annuals Resistance is out there • Resistance is out there ALS Inhibitors for POST Poa POST Poa Control Acetolactate Synthase Inhibitors • Branched chain amino acids • Low use rates, low mammalian toxicity • Used for cool‐season grass control in warm‐season turf • Several golf courses report poor annual bluegrass control in 2012 31 1/9/2015 Red = Resistant Red = Resistant 0 oz 0.06 oz 0.13 oz 0.26 oz 0.53 oz 1.06 oz 4.24 oz 2.12 oz ALS Resistant POAN 28 DAT with Trifloxysulfuron 139 oz 0 oz ALS Resistant POAN 28 DAT with Foramsulfuron Trifloxysulfuron at 4.24 oz/A + NIS at 21 DAT Resistant ab b b ab ab Susceptible ab c bc bc cdef cdefg cdefgdefg efg Resistant POAN Control 21 DAT Options? ALS Inhibitors for POST Poa POST Poa Control • Move to a PRE program – MOA mixtures/rotation – Specticle, Ronstar • Experiment with glyphosate POST • Hope for new MOA? 32 1/9/2015 Prevention and Management Prevention and Management • Proper Turfgrass Management Prevention and Management • Proper Turfgrass Management • Scout for Weed Escapes 33 1/9/2015 Prevention and Management • • • • Modeled Effects of Rotation on Triazine Resistance Proper Turfgrass Management Scout for Weed Escapes Site Specific Management Herbicide Rotation/Tank Mixtures Modeled Effects of Rotation/Mixtures on ALS Resistance 100.0 40.0 Risk of Deve eloping Resistance in 30 years Years to develop resistance (30%) • Proper Turfgrass Management • Scout for Weed Escapes • Site Specific Management Prevention and Management 30.0 20 0 20.0 10.0 0.0 No rotation 2 on : 1 off 1 on: 1 off 1 on : 2 off 75.0 50.0 25.0 0.0 No rotation ALS + quinclorac HPPD fb ALS ALS fb ACCase *Assumes rate for 95% control, 2 yr seed life, fitness = 1 Resistance (20%) observed within 4 years with ALS only program Gressel and Segel. 1990. Weed Technol. 4:186‐198 Bagavathiannan et al. 2014. Weed Tech. 28:89‐103 34 1/9/2015 Gerald Henry, PhD [email protected] @UGATurfgrass Jared Hoyle, PhD [email protected] @KSUTurf Q Questions? i ? 35