Turfgrass Selection. Turfgrass Selection and Maintenance. Transition Zone. Georgia. Cool vs. Warm Season Grasses 3/15/2017. Tough Environment.

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1 Transition Zone Turfgrass Selection and Maintenance Rebecca Grubbs PhD Candidate Gerald Henry, PhD Environmental Turfgrass Science University of Georgia Transition Zone Summer Too hot for cool season turf to perform well Winter Cold enough to injure or cause winter kill of warm season turf Georgia Tough Environment Hot summers Cool winters High humidity Acute drought Numerous soil types Cool vs. Warm Season Grasses Cool season Warm season Thrive in 65 to 75 F Thrive in 80 to 95 F Turfgrass Selection Spring Summer Fall 1

2 What to Consider Environment Temperature (summer and winter) Precipitation Sunlight/Shade Salinity/Soil ph Selecting the Right Grass Photo: Jim Brosnan, UT More than Herbicides Are Needed Here What to Consider Maintenance Establishment Irrigation Fertility Pesticides Soil amendments Use Traffic/Wear Aesthetics (color/texture) Common GA Turfgrass Species Cool season grasses Tall Fescue Hybrid Bluegrass Warm season grasses Bermudagrass (common/hybrid) Zoysiagrass Centipedegrass St. Augustinegrass Seashore Paspalum Tall Fescue Cool season grass Good heat and drought tolerance Good salinity tolerance Low disease potential Good wear tolerance Quick establishment Moderate fertility requirement Moderate cold tolerance Low density 2

3 Tall Fescue Home Lawn Partial sun/shade Needs Regular irrigation Occasional fertility Weed control Routine mowing 2.5 to 3.5 inches Overseeding in fall Rhizomatous Tall Fescue Added characteristics: Rhizomes (quick recovery) Deeper/denser root system (more drought tolerant) Increased waterlogging tolerance Hybrid Bluegrass Cool season grass Good heat and drought tolerance Good cold tolerance Good shade tolerance Low disease potential Moderate fertility requirement Moderate wear tolerance Heat Tolerant Bluegrasses Hybridization between Texas Bluegrass and Kentucky Bluegrass Available cultivars: Reveille, Longhorn, Bandera, Thermal Blue, Thermal Blue Blaze, DuraBlue, Solar Green, etc. Targeted for use in the transition zone where Kentucky bluegrass and Tall fescue are used Heat Tolerant Bluegrasses Aggressive rhizome system quicker establishment and spread Rhizome system recovers quick from damage less reseeding Powdery mildew resistance Golf Course, Athletic Field, Home Lawn Sod and seed Needs Regular irrigation Occasional fertility Routine mowing 0.75 to 2 inches Hybrid Bluegrass 3

4 Bermudagrass Warm season grass Common and hybrid Good drought tolerance Good heat tolerance Good wear resistance Moderate cold tolerance Moderate salinity tolerance Poor shade tolerance High fertility requirement High disease potential Bermudagrass Common bermudagrass More open turf, wider leaf blades, higher mowing height More cold tolerant Requires less maintenance Hybrid bermudagrass Denser turf, finer leaf blades, lower and more frequent mowing More fertilization High maintenance turf Common Bermudagrass Home Lawn, Golf Course, Athletic Field Sod, sprigs, seed Needs Regular irrigation Occasional fertility Full sun Routine mowing 0.5 to 2 inches Hybrid Bermudagrass Golf Course, Athletic Field, Home Lawn Sprigs and sod New seeded varieties Needs Regular irrigation High fertility Full sun Routine mowing 0.5 to 1.5 inches Zoysiagrass Warm season grass Good cold tolerance Good heat tolerance Good wear tolerance Moderate drought tolerance Moderate shade tolerance Moderate salinity tolerance Moderate fertility requirement High disease potential Slow establishment Zoysiagrass Golf Course, Athletic Field, Home Lawn Plugs and sod (seed available) Fine to coarse textured Needs Regular irrigation Occasional fertility Routine mowing 0.5 to 1.5 inches Have seen winter damage 4

5 Centipedegrass Warm season grass Good heat tolerance Low fertility requirement Low disease potential Low thatch accumulation tendency Low shoot density Poor cold tolerance Poor drought tolerance Poor shade tolerance Poor salinity tolerance Poor wear resistance Poor recuperative capacity Golf Course, Home Lawn Sod and seed Needs Regular irrigation Minimal fertility < 2 lb/1000 ft 2 Routine mowing 1.5 to 3 inches Have seen winter damage Centipedegrass Winter Damage St. Augustinegrass Warm season grass Good heat tolerance Good shade tolerance Good salinity tolerance Good recuperative capacity Moderate fertility requirement Poor cold tolerance Poor drought tolerance High disease potential Poor wear resistance Home Lawn Sod and plugs Needs Regular irrigation Moderate fertility 3 lbs/1000 ft 2 Routine mowing 2.5 to 4 inches Have seen winter damage St. Augustinegrass Seashore Paspalum Warm season grass Great salinity tolerance Great submersion tolerance Good heat tolerance Good drought tolerance Good recuperative capacity Moderate disease potential Moderate cold tolerance Moderate fertility requirement High thatching tendency Poor shade tolerance Seashore Paspalum Golf Course, Athletic Field, Home Lawn Seed, plugs and sod Needs Irrigation: 50% less than bermudagrass Occasional fertility Routine mowing to 1.5 to 3 inches Have seen winter damage 5

6 National Turfgrass Evaluation Program (NTEP) Information about turfgrass cultivar performance regarding Environment Disease pressure Wear tolerance Etc. Turfgrass Management Common Practices Irrigation Mowing Fertility Cultivation Pest Management Tall Fescue Bermudagrass Zoysiagrass Focus Species Irrigation Amount Irrigation Varies with grass species (rooting, etc.), soil type, and environmental conditions (evapotranspiration) Fescue & Zoysiagrass 1.0 to 1.25 inches/week Bermudagrass 1.0 inch/week 6

7 Irrigation Frequency Varies with local conditions Too frequent continuously wet soil surface resulting in a shallow root system Standard rule: apply water deeply and infrequently Sandy soils may require more frequent irrigation Patch diseases may be encouraged by deep, infrequent irrigation Irrigation Frequency Frequent Infrequent and Deep Irrigation Timing Time of Day: Night watering keeps turf wet for too long increased disease potential Day watering allows turf to dry, but evaporation is high Early morning hours are best evaporative loss is less and turf is allowed to dry Reducing Water Use Mowing Height: Higher heights = greater water use efficiency Fertility: High N may increase shoot growth rate requiring more water demand High N may also decrease root growth NDVI (Turfgrass Vigor) 90 DAT Mowing 7

8 Mowing Height Each species has its mowing tolerance range Below this range: Turf will thin or be overtaken by weeds Above this range: Increased disease pressure Puffiness Mowing Height Tall Fescue 2.5 to 3.5 inches during spring and fall 3.5 during summer reduce stress Bermudagrass 0.5 to 1.5 inches during spring and summer Raise 0.5 inch in fall reduce winter kill Zoysiagrass 0.5 to 1.5 inches during spring, summer, and fall Mowing Frequency Every 5 to 7 days Lower height = frequency Rules: Never remove more >1/3 leaf tissue per mowing Avoid mid day mowing when heat stress occurs Clippings Contribute little to thatch Can be safely returned if lawns are mowed regularly Returned clippings can contribute 2 lbs N/1000 ft 2 /year in addition to other nutrients Clipping removal may reduce weed seed Fertility N Fertility Programs Cool season grasses (Tall Fescue) Rates will vary with environmental conditions and soil type Lighter N applications in the spring Heavier N applications in the fall Avoid N applications in the summer Fe can be applied for green up 8

9 Cool Season N Program Timing Nitrogen (lb N/1000 ft 2 ) March/April May/June June/July 0 August 1.0 September 1.0 Late Fall N Fertility Programs Warm season grasses (Bermudagrass & Zoysiagrass) Rates will vary with environmental conditions and soil type 1.0 lb N/1000 ft 2 is recommended per growing month No more than ½ lb N in September to minimize Spring Dead Spot Excessive Nitrogen Fertilization Shoot Growth Extensive Roots Thatch Cultivation Common to intensely managed turf Development of an organic layer above the soil and below the canopy Composed of dead organic debris; living roots, crowns, and stems 9

10 Thatch Formation Some thatch accumulation is expected Results from improper turf management Excessive nitrogen fertilization Excessive watering Chemical imbalances in the soil Reductions in soil microorganisms Soil Compaction Occurs on heavily trafficked turf Pore space and oxygen levels are reduced Root elongation is reduced Cultivation Aerification/Verticutting Alleviate thatch and soil compaction Enhance rooting Increase water infiltration Increase gas exchange Decrease nutrient deficiencies 10

11 Solid tine Aerification Solid tine Aerification Aerification Depth Aerification Depth Insect Control Pest Management 11

12 White Grubs Several species of beetles have an immature or larval stage known as a grub White grubs as a group include: Japanese beetle European chafer Northern masked chafer Southern masked chafer Oriental beetle Asiatic garden beetle Green June beetle Black turfgrass ataenius May beetle Identification Fully grown white grub larvae: White or cream colored Three pairs of legs Brown head Dark area at posterior end of the body soil sack Size varies between age and species (1/4 to 2 inches long) Identified specifically by the raster pattern course hairs or spines on the underside of the last abdominal segment Life Stages Influencing Factors Grubs attack turf areas irregularly from year to year Two major factors influence grub numbers and severity of damage: Soil Moisture Rainfall Influencing Factors In years with normal or above normal rainfall, grub populations increase Turf next to ornamental plants favored by the adults are more commonly attacked Black turfgrassataeniusand green June beetle adults are attracted to turf with decaying thatch layers Cultural Control Host Plant Modifications Water/Irrigation Management 12

13 Host Plant Modifications Certain species of adult beetles prefer specific host plants Ex. Where Japanese beetles are common, do not plant roses, grapes, and linden trees around turf Ex. May/June beetles prefer oaks Ex. June beetles feed on ripening fruit such as peaches Fine and tall fescues are not as severely attacked as KBG and perennial ryegrass Water Management All white grubs require moist soil for their eggs to hatch Young larvae are also very susceptible to desiccation Some areas can stand a little moisture stress Do not water in July and early August White grubs and young larvae are present Water Management On the other hand, moderate grub infestations can be grown out Adequate water and fertilizer applied in August through September and again in May Peak grub feeding at this time This strategy is usually not preferred Mammals may dig up the turf searching for larvae Irrigation bans may occur Chemical Control Preventive Applications Early Reactive Applications Late Season Reactive Applications Spring Applications Preventive Applications Typically, applying pesticides for the control of anticipated grub populations is not recommended Occurrence is rather sporadic In areas where adult activity has been observed or perennial infestations have occurred, preventive applications may be warranted Preventive Applications Registered Products (good activity) Imidacloprid (Merit, ImidaPro, etc.) Halofenozide (Mach 2) Thiamethoxam (Meridian) Clothianidin (Arena) Chlorantraniliprole (Acelepryn) Perform best when applied before mid August, or when grub laying is underway 13

14 Early Reactive Applications Most insecticides have a short active residual period 3 weeks or less Must be used when grubs are actively feeding Usually observe 75 to 90% control Reapplication may be necessary when populations are high Early Reactive Applications Timing of the treatment is critical for success Apply when grubs are small and actively feeding yet late enough to catch all of the population Early Reactive Applications Late Season Reactive Applications Sometimes populations go undetected until September or October Grubs are usually third instars and may be 70 to 80 times the body weight of a newly hatched grub Chemical control is difficult Late Season Reactive Applications Late Season Reactive Applications Most successful insecticides (Curative): Carbaryl (Sevin) Trichlorfon (Dylox, Proxol, etc.) Irrigation after application will help keep grubs near the soil/thatch interface and wash in the pesticide 14

15 Spring Applications Spring Applications Spring treatments are often ineffective Grubs feed during the spring very large time for treatment is very small Make sure grubs are actively feeding at the soil/thatch level before application Most effective insecticides Carbaryl (Sevin) Trichlorfon (Dylox, Proxol, etc.) Adult Sampling Grub Sampling Maximizing Control Adult Sampling Light traps can be used May/June beetles Masked chafers Asiatic garden beetles Traps should be monitored 1 to 2 times/week Plot number of beetles collected over date sampled Once number of beetles drops over 7 days in a row, assume peak emergence and egg laying has occurred Adult Sampling Most eggs hatch in 14 to 21 days Insecticides can be applied three to four weeks after peak adult activity Grub Sampling Grub populations should be assessed when they are easily seen large enough Sample over a square foot area Can use a 4 inch cup cutter as well Take cores in a zigzag pattern across the turf area Grub populations of less than 6 per square foot can be masked with water and fertilizers 15

16 Grub Sampling Populations between 10 and 15 can cause significant damage in September and October Fire Ants Aggressive, reddish brown to black ants that are 1/8 to 1/4 inch long Notorious for painful, burning sting Allergic reactions can result in rashes and swelling to paralysis or anaphylactic shock Red Imported Fire Ant Control Ant baits are inexpensive, highly effective, and safe for the environment Baits plus insect growth regulators can be better for long term control Mound treatment and broadcast granules do not provide long term control and usually only kill foraging workers Chemical Control Baits/Mound Treatments: Award (fenoxycarb) Amdro (hydramethylnon) Advion (indoxacarb) Granular/Liquid Applications: Talstar (bifenthrin) Top Choice (fipronil) Disease Control Brown Patch Causal agent: Rhizoctonia solani Favored during warm (above 85 F) weather when night temps are above 68 F and foliage remains wet for extended (>10 hrs) periods 16

17 Brown Patch Symptoms (Cool season turf) Begins as small, circular, light green to darkpurplish patches that turn yellow and then brown Patches may expand to several feet in diameter Lesions (irregularly shaped grayish colored spots with dark brown margins) are more apparent on taller turf Brown Patch (Large Patch) Symptoms (Warm season turf) In warm season grasses, lesions do not form; rather, a soft, dark rot occurs on the lower portion of the leaf sheath Margins of patches exhibit yellow shoots Entire shoots can be pulled of the stolon Patches may be up to 20 ft Brown Patch Cultural Control Leaf lesion Dark rot on warm season turf leaves Avoid excessive nitrogen fertilization in late spring or summer Avoid prolonged leaf wetness Minimize shade Water during the day Provide good soil drainage Chemical Control Spring Dead Spot (SDS) Fungicides are very effective Can be applied preventatively or curatively Preventative applications late spring/early summer Products: Azoxystrobin (Heritage) Thiophanate methyl (Cleary s 3336) Propiconazole (Banner Max, etc.) Myclobutanil (Eagle) Occurs on home lawns, athletic fields, golf courses, and sod farms > 3 years old 17

18 Spring Dead Spot (SDS) Casual agents: Ophiosphaerella spp. These fungi are active in spring and fall 50 to 70 F soil temps. Infect roots, rhizomes, and stolons Spring Dead Spot (SDS) Primary host: Bermudagrass Most recently reported on zoysiagrass in GA Spring Dead Spot (SDS) Spring Dead Spot (SDS) Symptoms: Well defined circular dead spots a few inches to several feet in diameter become evident in spring Individual spots grow together to form large areas of disease Circular patch Coalescing patches Spring Dead Spot (SDS) Spring Dead Spot (SDS) Symptoms: Turfgrass leaves Bleached straw color Sunken/collapsed turf Roots, stolons, and rhizomes Black and rotted Sunken patches Necrosis of stolons and roots 18

19 Spring Dead Spot (SDS) Cultural Control Judicious use of nitrogen fertilizer Ammonium based nitrogen fertilizer combined with potassium Reduce thatch buildup and increase water infiltration through verticutting Raise mowing height of bermudagrass prior to winter Poor root system due to the presence of the disease Severely damaged area Cold Tolerance Do not make late fall N applications Allow for onset of dormancy Influence of N Source on Soil ph calcium nitrate increases ph, whereas ammonium sulfate reduces it roots absorb a nitrate ion (NO 3 ), a hydroxyl ion (OH ) is released, increasing rhizosphere ph NO 3 Soil Roots OH roots absorb an ammonium ion (NH 4 +), a hydrogen ion (H + ) is released, reducing rhizosphere ph NH 4 + H + Bermudagrass doesn t need fertility after September sulfate (SO 4 ) and calcium (Ca + ) have little to no effect on soil ph Influence of N Source on SDS Pressure Impact of Nitrogen Source on O. herpotricha Influence of N Source on SDS Pressure 90 Spring Dead Spot Diameter (cm) Sulfur Coated Urea Calcium Nitrate Urea Ammonium Sulfate Data: Dr. Lane Tredway, NCSU Photo: Dr. Lane Tredway, NCSU Urea 19

20 Influence of N Source on SDS Pressure Root Health K applications can help strengthen roots Photo: Dr. Lane Tredway, NCSU Ammonium Sulfate Cold Tolerance Raise mowing height prior to winter Buffers crowns Root Health Raise mowing height prior to winter Reduces root stress and may increase mass Chemical Control of SDS Fungicides applied in fall preventatively (Sept/Oct.) Irrigate to move the fungicides into the rootzone Historical Products: Fenarimol (Rubigan) no reregistration with EPA Thiophanate methyl (Cleary s 3336) Propiconazole (Banner Max, etc.) Myclobutanil (Eagle) Propiconazole + Azoxystrobin (Headway) Tebuconazole (Torque) Weed Control 20

21 What are your weeds telling you? Weeds as Indicators Soil Compaction Associated with high traffic, poor water infiltration, etc. Presence of prostrate knotweed, khakiweed, goosegrass Weeds as Indicators Low Soil Nitrogen Fertility Associated with low fertility inputs, sandy soil, etc. Presence of clover spp., black medic, common lespedeza Weeds as Indicators Wet/Saturated soils Associated with poor water infiltration, heavy clay soils, low lying areas Presence of sedge spp., annual bluegrass, goosegrass, carpetgrass, dichondra 21

22 Weeds as Indicators Low soil ph red sorrel High soil ph plantains Droughty soils prostrate spurge, black medic, knotweed, yellow woodsorrel High soil N Annual bluegrass, chickweeds, moss Low mowing height Algae, annual bluegrass, moss, chickweeds Photo: Pete Landschoot, PSU Plant Competition Why Control Them? Competition will occur if there is one limiting resource needed by two or more plants Plants compete for the following resources Light Water Nutrients Space Preemergence Weed Control Preemergence Herbicides Herbicides do not prevent weeds from germinating, they control weeds as they grow through the herbicide treated zone 22

23 Application Timing Preemergence Weed Control Summer Annuals Winter Annuals Target species: annual grasses; annual and some perennial broadleaf weeds Spring applications Initial app. late February to mid March Sequential app. approx. 60 days later Fall applications Mid to late September Spring Summer Fall Winter Preemergence Herbicides Application Technique is Critical Large gaps in herbicide barriers result in weed escapes Preemergence Herbicides Herbicides do not prevent weeds from germinating, they control weeds as they grow through the herbicide treated zone 23

24 Preemergence Herbicides Loss of MSMA Large gaps in herbicide barriers result in weed escapes POST Weed Control in Bermudagrass, Zoysiagrass and Bluegrass MSMA POST Weed Control of Several Key Weeds: Sedge species Dallisgrass Multi tillered crabgrass Sandbur Goosegrass Carpetgrass Yellow Woodsorrel Preemergence Herbicides More important than ever Preemergence herbicides: prodiamine (Barricade) dithiopyr (Dimension) pendimethalin (Pendulum) oxadiazon (Ronstar)* oryzalin (Surflan) *Not for home lawn use Photo: P. McCullough 4.5 M 5.5 M UT J. Brosnan Specticle 3.75 oz/a 28 WAIT 24

25 Specticle Not a good fit for trafficked or shaded turf! Long soil residual/ root pruning damage Overseeding safety Recovery from wear/traffic, stress, and damage Spring dead spot disease Specticle Photo: J. Brosnan, U Tenn Specticle Specticle Program Fall application If not overseeding or interseeding Long soil residual activity Provides some early control of summer annual weeds Can delay Spring preemergence applications insurance Rotate to another chemistry in Spring Photo: J. Brosnan, U Tenn DNA Herbicides Preemergence Herbicides Dinitroanalines (DNAs): Prodiamine (Barricade, Quali Pro Prodiamine) Oryzalin (Surflan, Quali Pro Oryzalin) Pendimethalin (Pendulum, Pre M, etc.) Oryzalin + benefin (XL) Rooting/Recovery Concerns 25

26 Root Pruning Damage Warm season turf issue stoloniferous grasses Herbicides are predominantly root absorbed Root Pruning Damage Can affect rooting of cool season sod Photo: J. Brosnan, U Tenn Preemergence Herbicides Oxadiazon (Ronstar, Quali Pro Oxadiazon)* Predominantly shoot absorbed Dithiopyr (Dimension, Quali Pro Dithiopyr) May cause similar damage to roots as DNA herbicides Bermudagrass Recovery from Spring Dead Spot in Response to Preemergence Herbicides *Not for home lawn use Bermudagrass Recovery from Spring Dead Spot Digital Image Analysis Applied March 20, 2012 Treatments: Barricade 21 fl oz/a Pendulum 3.5 pts/a Surflan 2 qts/a Dimension 1.5 pts/a Ronstar 5 pts/a Specticle 3.75 oz/a Tower 32 fl oz/a 26

27 Bermudagrass Recovery 2012 Untreated Check % SDS Recovery Recovery from 4/10 to 6/25/2012 6/20/2012 Ronstar Oxadiazon Barricade Prodiamine 6/20/2012 6/20/2012 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* 6/20/2012 *No cool season grass tolerance 27

28 Tower Crabgrass Trial Large Crabgrass Control 21 WAIT Herbicide Treatments Pendulum (April) fb Tower (May) Tower (April) fb Tower (May) Tower (April) fb Tower (May) fb Tower (June) Freehand (April) fb Freehand (May) 200 lb/a Freehand (April) fb Freehand (May) 400 lb/a Drive + Tower (May) Barricade (April) fb Barricade (May) % Crabgrass Cover Herbicide Treatments Untreated Check Pendulum fb Tower Tower fb Tower Tower fb Tower fb Tower Freehand fb Freehand low Freehand fb Freehand high Drive + Tower Barricade fb Barricade Sept. 15, 2011 Large Crabgrass Control 21 WAIT Postemergence Weed Control Pendulum fb Tower New Chemistries Celsius Formulation: 68 WG Active Ingredients: Thiencarbazone Iodosulfuron Dicamba Rate: 2.5 to 7.4 oz/a Tolerant Turf Species: warm season grasses Target Weeds: POST annual and perennial broadleaf weeds and grasses; Virginia buttonweed 28

29 Virginia Buttonweed Control Carpetgrass Control % Control % Control Initial apps. made in July Initial apps. made in July Tribute Total Formulation: 60.5 WG Active Ingredients: Thiencarbazone Foramsulfuron Halosulfuron Rate: 3.2 oz/a Tolerant Turf Species: bermudagrass only Target Weeds: POST sedge, broadleaf weeds, cool season grasses, large crabgrass, goosegrass, dallisgrass Blindside Formulation: 66 WG Active Ingredients: Sulfentrazone Metsulfuron Rate: 3.25 to 10 oz/a Tolerant Turf Species: cool season and warmseason grasses Target Weeds: POST grasses, sedges, and broadleaf weeds Ground Ivy Control Khakiweed Control Blindside 8 WAT Blindside 12 WAIT 29

30 T Zone Formulation: L Active Ingredients: Triclopyr Sulfentrazone 2,4 D Dicamba Rate: 3.25 to 4 pts/a (2 to 2.25 pts/a on dormant turf) Tolerant Turf Species: cool season grasses; dormant bermudagrass and zoysiagrass Target Weeds: POST broadleaf weeds 4 Speed XT Formulation: L Active Ingredients: 2,4 D Triclopyr Dicamba Pyraflufen Rate: 3 to 4 pts/a Tolerant Turf Species: cool season grasses; bermudagrass and zoysiagrass Target Weeds: POST broadleaf weeds Onetime Formulation: 2.45 SL Active Ingredients: Quinclorac MCPP Dicamba Rate: 64 oz/a Tolerant Turf Species: cool season grasses; bermudagrass and zoysiagrass Target Weeds: POST broadleaf weeds and grasses Difficult to Control Weeds Purple Nutsedge Tubers linked by chains of rhizomes Purple Nutsedge 30

31 Purple Nutsedge Postemergence Herbicide Options: Sulfosulfuron (Certainty) Safety on bermudagrass, zoysiagrass, and centipedegrass Trifloxysulfuron (Monument) Safety on bermudagrass and zoysiagrass Sulfentrazone + Imazethapyr (Dismiss South) Safety on bermudagrass, zoysiagrass, and centipedegrass Imazaquin (Image) Safety on established bermudagrass, zoysiagrass, centipedegrass, and St. Augustinegrass Purple Nutsedge Control in Common Bermudagrass fl oz or oz/a WAIT = Weeks After Initial Treatment Certainty 12 WAIT Dismiss South 12 WAIT Purple Nutsedge Control with Dismiss Crabgrass spp. Application date: 6/15/

32 Crabgrass spp. Postemergence Herbicides: Quinclorac (Drive XLR8) Safety on Bermudagrass, zoysiagrass, and tall fescue Will not interfere with seeding, reseeding, overseeding, or sprigging Formulated mixtures 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) Crabgrass spp. Postemergence Herbicides (cont.): Fenoxaprop (Acclaim Extra) Safety on zoysiagrass and tall fescue Safe on newly plugged zoysiagrass Low use rates on bermudagrass? Fluazifop (Fusilade II) Safety on zoysiagrass and tall fescue Avoid making apps. to stressed turf Crabgrass spp. Postemergence Herbicides (cont.): Mesotrione (Tenacity) Safety on dormant bermudagrass, centipedegrass and tall fescue (actively growing) POST activity on less than 4 tiller crabgrass Good PRE activity as well Tenacity Injury to Zoysiagrass Mature Large Crabgrass UGA Application time July 16, 2012 Site mature large crabgrass (multitillered) maintained at 2 inches Herbicide Treatments 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) Acclaim Extra (20 oz/a) + NIS + Dimension (0.25 pts/a) Acclaim Extra (28 oz/a) + NIS 32

33 Untreated Check 4 WAT Drive XLR8 + MSO 4WAT 64 fl oz/a Tribute Total + MSO 4 WAT Crabgrass spp. Postemergence Herbicides (cont.): Prodiamine + Sulfentrazone (Echelon) Safety on bermudagrass, zoysiagrass, centipedegrass and tall fescue Early POST control of seedling crabgrass but mainly PRE activity 3.2 oz/a Sethoxydim (Segment) Safety on centipedegrass Dallisgrass Dallisgrass Dallisgrass spreads through the production of short, thick rhizomes Effective control must target rhizome production 33

34 Dallisgrass Control TX September Application Tribute Total 2 or 3.2 oz/a + MSO + AMS October Application Tribute Total 2 or 3.2 oz/a + MSO + AMS Sept fb Oct Application 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 Results 37 WAIT Dallisgrass Control 37 WAIT Untreated Check 37 WAIT Rating - June 2011 % Control 6/6/2011 Tribute Total 3.2 oz/a Sept 37 WAIT Tribute Total 3.2 oz/a Oct 37 WAIT 6/6/2011 6/6/

35 Cultural + Chemical Control 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 Initial app. June 14, 2013 Sequential app. Aug. 28, 2013 Herbicide treatments (app. to verticut and non verticut): 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 8 WAIT % Control Before 2 nd App. Goosegrass Initial apps. made in June Cultural Control Chemical Control Alleviate compaction Aeration Reduce Traffic/Wear Hand Removal Small infestations 35

36 Chemical Control Quinclorac (Drive) 1 lb or oz/a No use on St. Augustinegrass, some damage to hybrid bermudagrass (Weed B Gone Max) contains 2,4 D, MCPP, and dicamba additional broadleaf control Fenoxaprop (Acclaim Extra or Bermudagrass Control for Lawns) 1.5 pts/a (repeat applications) use on cool season turf and zoysiagrass Foramsulfuron (Revolver) Use on warm season only; no home lawns Herbicide Resistance Management 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 Weed Science 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 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 the population will increase 36

37 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 37

38 ALS Inhibitors for 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 Red = Resistant 0 oz 0.06 oz 0.13 oz 0.26 oz 0.53 oz 1.06 oz 2.12 oz 4.24 oz ALS Resistant POAN 28 DAT with Trifloxysulfuron 38

39 Red = Resistant Prevention and Management 0 oz ALS Resistant POAN 28 DAT with Foramsulfuron 139 oz Prevention and Management Proper Turfgrass Management Prevention and Management Proper Turfgrass Management Scout for Weed Escapes Prevention and Management Proper Turfgrass Management Scout for Weed Escapes Site Specific Management Prevention and Management Proper Turfgrass Management Scout for Weed Escapes Site Specific Management Herbicide Rotation/Tank Mixtures 39

40 Years to develop resistance (30%) Modeled Effects of Rotation on Triazine Resistance No rotation 2 on : 1 off 1 on: 1 off 1 on : 2 off *Assumes rate for 95% control, 2 yr seed life, fitness = 1 Gressel and Segel Weed Technol. 4: Risk of Developing Resistance in 30 years Modeled Effects of Rotation/Mixtures on ALS Resistance No rotation ALS + quinclorac HPPD fb ALS ALS fb ACCase Resistance (20%) observed within 4 years with ALS only program Bagavathiannan et al Weed Tech. 28: E mail: rgrubbs@uga.edu gmhenry@uga.edu Office #: turf.uga.edu 40