Managing Dollar Spot on Golf Courses with Good Cultural and Chemical Practices. Bruce B. Clarke Rutgers University

Transcription

1 Managing Dollar Spot on Golf Courses with Good Cultural and Chemical Practices Bruce B. Clarke Rutgers University

2 Dollar Spot 2

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4 Dollar Spot Pathogen : Sclerotinia homoeocarpa (Rutstroemia spp. or Poculum spp.) Grasses Affected : Annual Bluegrass, Bahiagrass, Bentgrass, Bermudagrass, Centipedegrass, Fine-leaved Fescue, Kentucky Bluegrass, Ryegrasses, Tall Fescue, Zoysiagrass

5 What is the True Identity of the Dollar Spot Fungus? The lack of a sexual stage has made renaming this fungus difficult Molecular studies have suggested this pathogen belongs to the Rutstroemiaceae family Rutstroemia (Carbone and Kohn 199) Poculum (Holst-Jensen et al 1997)

6 How is This Reclassification Being Done? DNA has been extracted from isolates of the dollar spot pathogen from throughout the world. The DNA has been sequenced from 8 gene regions that are unique to the dollar spot fungus This will allow for the proper reclassification of the fungus that causes dollar spot disease on cool- and warmseason turfgrases

7 Preliminary Results: Phylogenetic Analysis 0.08 MCM7 MAFF2698 Sclerotinia homoeocarpa RE1868 Sclerotinia homoeocarpa A Sclerotinia homoeocarpa SH Sclerotinia homoeocarpa MAFF2585 Sclerotinia homoeocarpa CBS Sclerotinia homoeocarpa MAFF2691 Sclerotinia homoeocarpa MAFF25856 Sclerotinia homoeocarpa CBS10.7 Sclerotinia homoeocarpa CBS11.7 Sclerotinia homoeocarpa CBS6.7 Rutstroemia paludosa CBS09.7 Sclerotinia homoeocarpa D1068 Rutstroemia macrospora D797 Poculum sp. D796 Poculum sp. 195 Rutstroemia sp. MAFF2695 Sclerotinia homoeocarpa AK116 Ciboria peckiana D80 anzia allantospora SD1295 Poculum sp. SB118 anzia griseliniae AK107 Ciboria peckiana D2125 Rutstroemia macrospora AK116 Ciboria peckiana D127 Poculum sp. D109 anzia berggrenii CBS200.7 ambertella viburni D1172 Poculum sp. D100 anzia aureus D199 anzia quadrispora D101 anzia griseliniae CBS1.62 Rutstroemia firma CBS Rutstroemia sydowiana CBS Rutstroemia conformata Sclerotinia sclerotiorum SS5 Sclerotinia sclerotiorum SS1 Sclerotonia sclerotiorum SS MAFF7020 Sclerotinia minor Monolinia vaccinii-corymbosi 1 Dollar spot fungus samples Bennett s 197 dollar spot samples Rutstroemia type species for the genus Rutstroemia

8 Preliminary Results: Phylogenetic Analysis ITS MAFF2691 Sclerotinia homoeocarpa RCCPG1 Sclerotinia homoeocarpa HP50 Sclerotinia homoeocarpa MB1 Sclerotinia homoeocarpa D100 anzia aureus MAFF25855 Sclerotinia homoeocarpa SH Sclerotinia homoeocarpa CBS Sclerotinia homoeocarpa RE1868 Sclerotinia homoeocarpa EF117T21 Sclerotinia homoeocarpa MAFF2585 Sclerotinia homoeocarpa DRR9 Sclerotinia homoeocarpa MAFF25858 Sclerotinia homoeocarpa MAFF2698 Sclerotinia homoeocarpa TEKP2 Sclerotinia homoeocarpa FD1 Sclerotinia homoeocarpa BC1 Sclerotinia homoeocarpa RB19 Sclerotinia homoeocarpa CBS09.7 Sclerotinia homoeocarpa CBS85.97 Rutstroemia calopus CBS65.7 Rutstroemia cunicularia CBS6.7 Rutstroemia paludosa D1295 Poculum sp. SB118 anzia griseliniae AK116 Ciboria peckiana SSI1 Monolinia vaccinii-corymbosi SSI2 Monolinia vaccinii-corymbosi D1172 Poculum sp. AK116 Ciboria peckiana SA25 Rutstroemia macrospora D58 anzia bergrenii D796 Poculum sp. D797 Poculum sp. CBS200.7 ambertella viburni D109 anzia berggrenii D127 Poculum sp. SA195 Rutstroemia sp. MAFF2695 Sclerotinia homoeocarpa MAFF7020 Sclerotinia minor Sclerotinia sclerotiorum SS5 Sclerotonia sclerotiorum SS Sclerotinia sclerotiorum SS1 CBS Rustroemia conformata CA Dollar spot samples Rutstroemia Poculum True Sclerotinia MAFF25856 Sclerotinia homoeocarpa HP50 Sclerotinia homoeocarpa MAFF2691 Sclerotinia homoeocarpa MB1 Sclerotinia homoeocarpa EF17T21 Sclerotinia homoeocarpa D100 anzia aureus SH80 Sclerotinia homoeocarpa SH Sclerotinia homoeocarpa MAFF2585 Sclerotinia homoeocarpa RG1868 Sclerotinia homoeocarpa A Sclerotinia homoeocarpa MAFF25858 Sclerotinia homoeocarpa D199 anzia quadrispora RCCPG1 Sclerotinia homoeocarpa MAFF2698 Sclerotinia homoeocarpa MAFF25855 Sclerotinia homoeocarpa MAFF7020 Sclerotinia minor DRR9 Sclerotinia homoeocarpa TEKP2 Sclerotinia homoeocarpa FD1 Sclerotinia homoeocarpa RB19 Sclerotinia homoeocarpa CBS09.7 Sclerotinia homoeocarpa CBS65.7 Rutstroemia cunicularia CBS6.7 Rutstroemia paludosa CBS85.97 Rutstroemia calopus CBS10.7 Sclerotinia homoeocarpa CBS11.7 Sclerotinia homoeocarpa D101 anzia griseliniae SA25 Rutstroemia macrospora D1068 Rutstroemia macrospora AK107 Ciboria peckiana SD2125 Rutstroemia macrospora MAFF2695 Sclerotinia homoeocarpa SA195 Rutstroemia sp. D1295 Poculum sp. D1172 Poculum sp. D796 Poculum sp. CBS Rutstroemia conformata CBS1.62 Rutstroemia firma Sclerotonia sclerotiorum SS Sclerotinia sclerotiorum SS1 Sclerotinia sclerotiorum SS5 SSI 1 Monolinia vaccinii-corymbosi Cool-season grass hosts Warm-season grass hosts

9 Conclusions Modern collections of the dollar spot fungus differ from Bennett s 197 samples Divisions between warm- and cool-season isolates are apparent The dollar spot pathogen is not a member of the genus Rutstroemia Data supports creating a new genus for this pathogen

10 Dollar Spot Conditions Favoring Disease : Overwinters as Sclerotia / Mycelium Resumes Growth at 59 0 F Optimum Disease F High RH (> 85% Night) Thick Thatch (> in.) ow Soil Moisture Extended Dew ow N Fertility

11 Cultural Management of Dollar Spot Maintain balanced N,P,K fertility Maintain adequate N when dollar spot is active ight, frequent N applications Avoid drought stress Do not irrigate toward dusk Remove dew by mowing, poling, or rolling Remove trees to provide good air circulation Aerify to reduce compaction and thatch

12 Dragging fairways Image courtesy Keith Happ

13 Past Research has Shown that Mowing Can : Reduce dollar spot 7 78% when done in the early morning (effect was greater on Fwy then Greens) Reduce dollar spot more if done at am than waiting until 10 am Reduce the incidence of dollar spot when dew is removed daily by mowing vs mowing on alternate days Improve fungicide effectiveness for the control of dollar spot when done prior to spraying (will be discussed later) (Williams et al ; Ellramet al., 2007; Pigatiet al., 2010)

14 Management of Dollar Spot- continued Organic fertilizers and composts can reduce dollar spot but this is due more to increased N availability than to enhanced microbial activity in the soil (Dernoeden, 200) Some biocontrol agents have been shown to reduce dollar spot in the field (Enterobacter cloacae and Bacillus subtilis) Microbial products containing Trichoderma harzianum (Root Shield), Bacillus licheniformis (Ecoguard), and Pseudomonas aureofaciens strain TX-1 can reduce dollar spot but often not to commercially acceptable levels alone Use new improved bentgrass cultivars whenever possible

15 Bentgrass Cultivar Classification of Dollar Spot Resistance* Most Tolerant Moderate Tolerant Moderate Susceptible Highly Susceptible 007 Authority Alpha Century 1-M -9 Bengal Crenshaw Benchmk DSR Penn A-1 Backspin Imperial Declaration Penn A-2 Grand Prix Independence Kingpin Penncross Mackenzie 18 th Green Pennlinks II Pennlinks Penn A- Memorial Seaside PenneagleII Seaside II Penn G SR 1150 Princeville Providence *Table developed from data from NTEP *and bentgrass trials at Rutgers University Southshore SR 1119

16 th 18 Green Declaration (HTE)

17 Chemical Control of Dollar Spot I. Benzimidazoles Fungo, Cleary 6 II. Demethylation Inhibitors (Sterol Inhibitors) Banner, Bayleton, Eagle, Rubigan, Triton Trinity, Tourney, Torque III. Dicarboximides Chipco 26GT Curalan, Touche, Vorlan IV. Dithiocarbamates Fore, Dithane, Pentathlon, Protect V. Nitriles Daconil, Echo, ChloroStar VI. Carboximides Emerald VII. QoI (strobilurins) Insignia, Disarm

18 Control Dollar Spot Control on Agrostis stolonifera Fairway Rutgers 2007

19 New Turfgrass Fungicides Trade Name Common Name FRAC # Civitas + Harmonizer mineral oil + pigment P Daconil Action chlorothalonil + acibenzolar M5 + P1 Segway cyazofamid 21 Trinity 1.69SC triticonazole Triton triticonazole Torque tebuconazole Tourney metconazole Velista penthiopyrad 7

20 Relative Effectiveness of New Turfgrass Fungicides: Cool-Season Turfgrasses Golf a Algae Anthracnose Brown Patch Brown Ring Patch Copper Spot Dead Spot Dollar Spot Fairy Ring Gray eaf Spot Gray Snow Mold Civitas + Harmonizer c Dac Action Segway Trinity b,c 2.5 x Triton b,c 2.5 Torque.5 b,c Tourney b,c x 2 Velista Stimulated a Efficacy on a 1 - scale, where 1 = not effective, 2 = fair - good control, = good - excellent control, and = excellent control. b Reduced sensitivity to DMI fungicides reported. c Phytotoxicity possible during hot weather

21 Relative Effectiveness of New Turfgrass Fungicides: Cool-Season Turfgrasses Golf a Algae Anthracnose Brown Patch Brown Ring Patch Copper Spot Dead Spot Dollar Spot Fairy Ring Gray eaf Spot Gray Snow Mold Civitas + Harmonizer c Dac Action Segway Trinity b,c 2.5 x Triton b,c 2.5 Torque.5 b,c Tourney b,c x 2 Velista Stimulated a Efficacy on a 1 - scale, where 1 = not effective, 2 = fair - good control, = good - excellent control, and = excellent control. b Reduced sensitivity to DMI fungicides reported. c Phytotoxicity possible during hot weather

22 Civitas + Harmonizer? Civitas is a mineral oil (Acropetal penetrant) - mixture of food-grade synthetic isoparaffins and a food-grade emulsifier developed by Suncor (Petro-Canada) Mode of action: Induced systemic resistance (activates plant signaling genes/antimicrobial compounds). Harmonizer (green pigment) Civitas, was registered in the U.S. in Feb 2009.

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24 applications Civitas (16.0 fl oz + Harmonizer 1.0 fl oz) R. atin 2010

25 applications Emerald 0.9 oz R. atin 2010

26 Daconil Action Chlorothalonil + acibenzolar Syngenta released for sale fall 2011 Acibenzolar belongs to FRAC group P and induces host plant defense Stimulates natural defense or SAR Controls every disease that Daconil does + some suppression of Pythium Improves turfgrass quality compared to chlorothalonilalone On many rating dates has shown improved $ spot and anthracnose control when compared to same rate of chlorothalonil

27 Untreated Daconil Action 1.5 fl oz 7 day A oz 7 day Daconil Ultrex.2 oz 1 day Photos taken at Rutgers Univ. bent green on August 27,2010

28 Trial conducted by Steve McDonald, Turfgrass Disease Solutions *Number of infection centers per plot area. Applications made on May 12 and 27

29 Velista (DPX-EM17) Active ingredient: penthiopyrad SDHI fungicide acropetal penetrant Fungicide class: carboximide FRAC group: 7 Formulation: 50WDG Application rate: oz 1000-ft -2 ate 2011: Approved in Canada; pending in US: anthracnose red thread dollar spot gray snow mold brown patch large patch leaf spot rust

30 The vital role of the respiratory pathway in fungi makes a good target for new pesticides complex III QiI (inside) inhibitors like cyazofamid (Segway) complex III Qo (outside) inhibitors like the QoI (strobilurins) fungicides complex II inhibitors like carboxin, boscalid, penthiopyrad (Velista)

31 FRAC has classified fungicide classes according to their risk for resistance development DuPont DPX-EM17 fungicide low risk copper salts copper EBDC's mancozeb melanin inhibitors nitriles chlorothalonil sulphur SAR-inducers acibenzolar medium risk EBI's DMIs anilinopyrimidines phenylpyrroles fluioxonil medium-high SDHI s boscalid, EM17 high risk benzimidazoles thiophanate dicarboximides phenylamides QoI s iprodione mefenoxan Strobilurins 1/8/2012 page 1

32 Velista (DPX-EM17 50WG) Excellent brown patch material Very good on dollar spot Not as long residual as Emerald Good anthracnose rotational material Good fit for early- to mid-summer (DS & BP) P. Majumdar

33 % Dollar Spot Dollar spot control on creeping bentgrass fairway UCONN DPX-EM oz 21-d 20 DAT 1 DAT 18 DPX-EM oz 21-d 16 Daconil Ultrex.2 oz 1-d 1 12 Banner MAXX 2.0 fl oz 21-d 10 untreated 8 21-d Jun 21-Jun 1-Jul 11-Jul 21-Jul 1-Jul 10-Aug *Applied every 1-d or 21-d from early-jun through late-jul 2010

34 Chemical Control of Dollar Spot New Fungicide Mixtures: Concert (chlorothalonil + propiconazole) Disarm C (fluoxastrobin + chlorothalonil) Disarm M (fluoxastrobin + myclobutanil) Honor (boscalid + pyraclostrobin) Instrata (chlorothalonil + propiconazole + fludioxonil) Interface (iprodione + trifloxystrobin) Pillar (pyraclostrobin + triticonazole) Renown (chlorothalonil + azoxystrobin) Reserve (chlorothalonil + triticonazole) Tartan (trifloxystrobin + triadimefon)

35 Concert Relative Efficacy of New Turfgrass Fungicide Mixtures: Cool-Season Grasses - Golf Algae Anthracnose Brown Patch.5 Brown Ring Patch Copper Spot Dead Spot Dollar Spot Fairy Ring Gray eaf Spot Gray Snow Mold Disarm C.5 Disarm M Honor Instrata.5 Interface.5 Pillar 2.5 Renown.5 Reserve Stellar a Efficacy on a 1 - scale, where 1 = not effective, 2 = fair - good control, = good - excellent control, and = excellent control. b Reduced sensitivity to DMI fungicides reported. c Phytotoxicity possible during hot weather

36 Concert Relative Efficacy of New Turfgrass Fungicide Mixtures: Cool-Season Grasses - Golf Algae Anthracnose Brown Patch.5 Brown Ring Patch Copper Spot Dead Spot Dollar Spot Fairy Ring Gray eaf Spot Gray Snow Mold Disarm C.5 Disarm M Honor Instrata.5 Interface.5 Pillar 2.5 Renown.5 Reserve Stellar a Efficacy on a 1 - scale, where 1 = not effective, 2 = fair - good control, = good - excellent control, and = excellent control. b Reduced sensitivity to DMI fungicides reported. c Phytotoxicity possible during hot weather

37 Curative Control of Dollar Spot (Fairway) : Rutgers 2011* * 21 day interval from June 1 to August 10

38 Influence of Fungicides on Dollar Spot (Green) : Rutgers, 2011* *Fungicides applied from May 2 to August 2

39 New Turfgrass Fungicide Formulations Trade Name Common Name FRAC # Disarm G fluoxastrobin 11 Headway G azoxystrobin + propiconazole 11+ Hertiage G azoxystrobin 11 Insignia Intrinsic pyraclostrobin 11

40 Relative Efficacy of New Formulations of Currently Available Turfgrass Fungicides: Cool-Season Turfgrasses - Golf Algae Anthracnose Brown Patch Brown Ring Patch Copper Spot Dead Spot Dollar Spot Fairy Ring Gray eaf Spot Gray Snow Mold Disarm G Headway G 1.5 X Hertiage G Insignia Intrinsic 1 2.1SC a Efficacy on a 1 - scale, where 1 = not effective, 2 = fair - good control, = good - excellent control, and = excellent control. b Reduced sensitivity to DMI fungicides reported. c Phytotoxicity possible during hot weather

41 Relative Efficacy of New Formulations of Currently Available Turfgrass Fungicides: Cool-Season Turfgrasses - Golf Algae Anthracnose Brown Patch Brown Ring Patch Copper Spot Dead Spot Dollar Spot Fairy Ring Gray eaf Spot Gray Snow Mold Disarm G Headway G 1.5 X Hertiage G Insignia Intrinsic 1 2.1SC a Efficacy on a 1 - scale, where 1 = not effective, 2 = fair - good control, = good - excellent control, and = excellent control. b Reduced sensitivity to DMI fungicides reported. c Phytotoxicity possible during hot weather

42 Insignia SC -- pyraclastrobin Honor -- pyraclastrobin & boscalid Disease control and Improved Plant Health

43 Root depth of Penncross creeping bentgrass treated with pyraclastrobin -- Univ. of Tenn. Irrigation Regime Treatment light frequent deep infrequent root depth (inches) Insignia SC 11.5 a 11.7 a Honor 11.7 a 11.5 a untreated 11.7 a 10.7 b *2 days after initial treatment **However no effect on turf quality** Brosnan et al. 2010

44 Summary Strobilurins are excellent broad spectrum fungicides Further research is needed to document the effect of strobilurins on turf health Greenhouse Field Studies Use these fungicides for disease control..any potential additional benefits are bonus

45 Improving Fungicide Performance Predictive Models Water ph /...Wash-Off Dollar Spot Water Volume / Dew Removal Nozzle Selection

46 How Does Water Volume and Dew Removal Affect Fungicide Efficacy?

47 Effect of Dew Removal on Fungicide Effectiveness for control of Dollar Spot Fungicide applied morning with dew Fungicide applied after dew removed Contact fungicide (e.g., Daconil oz) provided better dollar spot control when dew was removed in the morning Dew prevents contact fungicides from spreading over the leaf to provide complete protection. (McDonald and Dernoeden, 2007)

48 Effect of Dew Removal on Fungicide Effectiveness for Control of Dollar Spot Fungicide applied morning with dew Fungicide applied after dew removed Propiconazole (Banner 0.5 fl oz) Dew had no effect on the efficacy of this penetrant fungicide 21 days after last treatment.

49 Recommendations For contacts, use gallons water per 1,000 sq ft was optimum for dollar spot control. Under very severe dollar spot pressure, use maximum rates and 2.0 gallons water / 1,000 sq ft. Remove dew to improve the performance of contact fungicides (e.g., chlorothalonil), but not DMI fungicides (e.g., propiconazole). The tank mixture of contact (chlorothalonil) and penetrant (propiconazole) provided better disease control than either applied alone under high disease severity

50 What Impact does Nozzle Selection have on Fungicide Efficacy?

51 Nozzle Types XR and XRC TeeJet TwinJet Turbo TeeJet Flat Fan Spray Pattern TurfJet AI TeeJet (Air Induction) Raindrop Turbo TwinJet Hollow Cone Spray Pattern

52 Spray Coverage Excellent XR Nozzle Fine to Medium Turbo TeeJet Medium to Coarse Air-induction Course to Very Coarse TurfJet Extremely Coarse Poor Raindrop Extremely Coarse

53 Nozzle Coverage Water sensitive paper turns blue when it makes contact with water Raindrop TurfJet XR nozzle Airinduction 50 GPA = 1.15 gallons per 1000 sq. ft.

54 Poor Drift Control Excellent Raindrop TurfJet Air-induction Turbo TeeJet XR nozzle

55 AI/AIC TeeJet Nozzles Advantages Good coverage Uses Venturi-air technology Drift control Even at very high pressure Works best at >0psi Canopy penetration Disadvantages Not useable at low pressures (<0 psi) Wear tolerance

56 Spray Solution Air-induction Air Spray Solution Air

57 What Impact does Water Volume and Nozzle Type have on Fungicide Efficacy?

58 Impact of Water Volume and Nozzle Type on Dollar Spot Control Number of lesion Centers gal/1000 ft² (chlorothalonil - Daconil 1.8 oz/ M) AI Turbo XR Del. Untr. Nozzle Type Fidanza: Research Conducted for Rutgers Field Day

59 Impact of Water Volume and Nozzle Type on Dollar Spot Control Number of lesion Centers gal/1000 ft² (chlorothalonil oz/ M) AI Turbo XR Del. Untr. Nozzle Type Fidanza: Research Conducted for Rutgers Field Day

60 Impact of Simulated Rainfall Dollar Spot Control: Rutgers 2009 Five Fungicide Treatments Daconil Ultrex (1.8) Chipco 26GT (.0) Trinity (1.0) Renown (mixture of chlorothalonil and azoxystrobin) Disarm (0.18) Half inch rainfall treatments were applied Immediately following application (within 5 minutes) Four hours after application 2 hours after application None

61 NO WATER immediately following EFFECT OF SIMUATED RAINFA ON DOAR SPOT CONTRO WITH Chipco 26GT fl oz/1,000 sq ft

62 CHIPCO 0.5 INCHES FOUR HOURS AFTER Untreated EFFECT OF SIMUATED RAINFA ON DOAR SPOT CONTRO WITH Chipco 26GT fl oz/1,000 sq ft

63 Summary All fungicide treatments reduced dollar spot when compared to untreated All fungicides were impacted by simulated rainfall. Chlorothalonil (contact fungicide) was most affected by rainfall immediately following application Iprodione (localized penetrant) appeared to be the best treatment when irrigation was applied hours after treatment

64 What Impact of Water ph on Fungicide Efficacy?

65 What is the Impact of ph on the Control of $-Spot? Most pesticides stable at ph to 6 Some fungicides decompose ph > 7. -alkaline hydrolysis -loss of pesticide efficacy -examples: -Polyoxin D (Endorse) fungicide -Thiophanate methyl (Cleary s 6) Refer to product MSDS sheet for ph stability information

66 Impact of Water ph on Dollar Spot Control with Cleary 6 2 oz/m Dollar Spot (# Infection Centers) c c Untr. Water Carrier ph b a Rutgers, bentgrass green, July 19, 2007.

67 Dollar Spot (# Infection Centers) Impact of Water ph on Dollar Spot Control with Daconil Ultrex (1.8 oz/m) d d d Untr. b Water Carrier ph ab a Bellewood GC, bentgrass fairway, July 11, 2006 Fidanza (PSU)

68 Impact of Water ph on Dollar Spot Control with Banner 0.5 fl oz/m Dollar Spot (# Infection Centers) b b b b b Untr. Water Carrier ph a Bellewood GC, bentgrass fairway, July 11, 2006 Fidanza (PSU)

69 And ast but not east, Should You Rethink the Timing of Your Fungicide Program for the Control of Dollar Spot on Fairways?

70 Photo July 7, 200 Dr. Mike Boehm, Ohio State Univ #5 Fairway No early spring applications

71 Photo July 7, 200 Dr. Mike Boehm, Ohio State Univ #5 Fairway with one early spring application

72 Early Season Dollar Spot Suppression with a Single Application of Various Fungicides, # esion centers / plot 1 Treatment and rate / 1000 sq ft 6 June 20 June Curalan 50EG 1.0 oz 1 a 10 a Banner MAXX 1.ME 1.0 fl oz 6 ab 1 a Emerald 70 WG 0.1 oz 9 a-c 19 a Bayleton 2SC 1.0 fl oz 11 a-c 19 a Chipco 26GT 2SC 2.0 fl oz 18 b-d 0 ab Daconil Ultrex 82.5WDG 1.8 oz c-e 5 b Insignia 20WG 0.5 oz 6 de 56 b Untreated Check 89 f 87 c 1 Treatments were applied on 1 April, (6 June = 7.7 WAT; 20 June = 9.7 WAT) F & N 2007: Kaminski

73 Delaying the Initial Outbreak and Severity of Dollar Spot on Fairways with an Early Spring Application of Fungicides? One Early Spring Application - with an effective dollar spot fungicide or a tank mixture of two good dollar spot fungicides after the Second True Mowing of the season

74 Summary of Cultural and Chemical Control Practices to Reduce Dollar Spot Severity Mow As Early As Possible When Dollar Spot Is Active Keep Soil Moist ( 25%). Do Not Over Irrigate. Spoon feed N (Ammonium sulfate good, but can burn). Tank Mixes reduce potential for Resistance, improves & extends control and suppresses other diseases Always Tank Mix QoIs when DS is Active Using ow Rates of DMI s and Trimmit/Cutless (Can speed development of DMI Resistance) (Peter Dernoeden)

75 Are There any Questions? Dr. Clarke and his graduate students and field crew