managing dollar spot with good cultural and chemical practices · managing dollar spot with good...

Managing Dollar Spot with Good Cultural

and Chemical Practices

Bruce B. Clarke

Rutgers University

www.turf.rutgers.edu

Dollar Spot Disease

• Most common fungal disease of cool-season turfgrasses

• Distributed worldwide, on both warm- and cool-season turfgrass hosts

• More fungicides used to control/manage dollar spot than any other

fungal disease of turfgrass

Dollar Spot

Conditions

Favoring

Disease :

Overwinters as Sclerotia / Mycelium

Resumes Growth at 59 0F

Optimum Disease 70 – 84 0F

High RH (> 85% Night)

Thick Thatch (> 0.5 – 0.75 in.)

Low Soil Moisture

Extended Dew

Low N Fertility

Cultural Management of Dollar Spot

Maintain balanced N,P,K fertility

Maintain adequate N when dollar spot is active

Light, 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

Dragging fairways

Image courtesy Keith Happ

Dollar Spot Creeping Bentgrass Putting Green Clarke, et. al. - Rutgers University - 2005

Denotes significant difference b/w DewCure and untreated control

DewCure applications made at 14 d intervals*

0

20

40

60

80

100

120

140

6/3

6/10

6/17

6/24 7/

17/

87/

157/

227/

29 8/5

8/12

DewCure 2 oz

Check

*

*

**

*

No

. L

esio

ns

per

Plo

t

*

*

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, 2003)

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

Bentgrass Cultivar Classification of Dollar Spot Resistance*

Most Tolerant Moderate Tolerant

Moderate Susceptible

Highly Susceptible

007 Authority Alpha Century

1-3M L-93 Bengal Crenshaw

Benchmk DSR Penn A-1 Backspin Imperial

Declaration Penn A-2 Grand Prix Independence

Kingpin Penncross Mackenzie 18th Green

Pennlinks II Pennlinks Penn A-4

Memorial Seaside PenneagleII

Seaside II Penn G

SR 1150 Princeville

Providence

Southshore

SR 1119

*Table developed from data from NTEP *and bentgrass trials at Rutgers University

18th

Green Declaration (HTE)

Chemical Control of Dollar Spot

I. Benzimidazoles

Fungo, Cleary 3336

II. Demethylation Inhibitors(Sterol Inhibitors)

Banner, Bayleton,

Eagle, Rubigan

III. Dicarboximides

Chipco 26GT

Curalan, Touche, Vorlan

IV. SDHI/Carboximides

Emerald, Velista, Xzemplar Kabuto

V. Dithiocarbamates

Fore, Dithane, Pentathlon, Protect

VI. Nitriles

Daconil, Echo,

ChloroStar

VII. Pyridinamines

Secure

VIII. QoI’s (Strobilurins) Insignia, Diarm

Controlling of Dollar Spot with

Fungicides

Control Dollar Spot Control on Agrostis

stolonifera Fairway – Rutgers 2007

Dollar Spot Trial 2011: Rutgers UniversityCrenshaw Creeping Bentgrass (Fairway Height)

Applications: May 24; June 7, 21; Jul 5, 19; Aug 2, 16.

*Rate per 1,000 ft².

Velista (penthiopyrad)

P. Majumdar

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)

Relative Efficacy of New Fungicides for Cool - Season Turf

Diseases : 2005- 2011 (Golf)

* Efficacy on a 1- 4 Scale, where 1 = not effective, 2 = fair – good control, 3 = good – excellent control, and 4 = excellent

control. Limited = insufficient data.

0

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.

Relative Efficacy of New Fungicides for Cool - Season Turf

Diseases : 2015

* Efficacy on a 1- 4 Scale, where 1 = not effective, 2 = fair – good control, 3 = good – excellent control, and 4 = excellent

control. Limited = insufficient data.

0

3 applications Civitas (16.0 fl oz + Harmonizer 1.0 fl oz)

R. Latin 2010

3 applications Emerald 0.9 oz

R. Latin 2010

Evaluating Tank Mixtures for the

Control of Dollar Spot

Summary of Cultural and Chemical Control

Practices to Reduce Dollar Spot Severity

Rotate and tank mix to improve fungicide efficacy and

reduce the potential for fungicide resistance

Make sure all components of premixes control dollar

spot or other key diseases

Time application of the fungicide to take advantage of

its strengths and to limit potential problems

Improving Fungicide Performance

Predictive

Models

Water Volume /

Dew Removal

Nozzle

Selection

Dollar Spot

Water pH /

...Wash-Off

How Does Water Volume and Dew

Removal Affect Fungicide Efficacy?

Effect of Dew Removal on Fungicide

Effectiveness for control of Dollar Spot

• Contact fungicide (e.g., Daconil Ultrex @1.8 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)

Fungicide applied morning with dew Fungicide applied after dew removed

Effect of Dew Removal on Fungicide

Effectiveness for Control of Dollar Spot

• Propiconazole (Banner MAXX @ 0.5 fl oz)

• Dew had no effect on the efficacy of this penetrant fungicide

• 21 days after last treatment.

Fungicide applied morning with dew Fungicide applied after dew removed

Recommendations

• For contacts, use 1.0 – 2.0 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

What Impact does Nozzle Selection

have on Fungicide Efficacy?

XR and XRC TeeJet Turbo TeeJet

AI TeeJet

(Air Induction) TurfJet

Raindrop

TwinJet

Nozzle Types

Turbo TwinJet

Hollow Cone”

Spray Pattern

Flat

Fan”

Spray

Pattern

Spray Coverage

Excellent

Poor

RaindropExtremely Coarse

XR NozzleFine to Medium

TurfJetExtremely Coarse

Turbo TeeJetMedium to Coarse

Air-inductionCourse to Very

Coarse

Nozzle Coverage

TurfJetRaindrop

XR nozzle Air-induction

50 GPA = 1.15 gallons per 1000 sq. ft.

Water sensitive paper – turns blue when it makes contact with water

Drift Control

Excellent

Poor

Raindrop

XR nozzle

TurfJet

Turbo TeeJet

Air-induction

AI/AIC TeeJet Nozzles

• Advantages

– Good coverage

– Uses Venturi-air technology

– Drift control

• Even at very high pressure

– Works best at >40psi

– Canopy penetration

• Disadvantages

– Not useable at low pressures

(<30 psi)

– Wear tolerance

Air-inductionSpray Solution

Air

Air

Spray Solution

What Impact does Water Volume and

Nozzle Type have on Fungicide

Efficacy?

Impact of Water Volume and Nozzle Type on

Dollar Spot Control

0

10

20

30

AI Turbo XR Del. Untr.

Nozzle Type

Num

ber

of le

sio

n C

ente

rs

Fidanza: Research Conducted for Rutgers Field Day - 2005

0.5 gal/1000 ft² (chlorothalonil - Daconil Ultex @ 1.8 oz/ M)

Impact of Water Volume and Nozzle Type on

Dollar Spot Control

0

10

20

30

AI Turbo XR Del. Untr.

Nozzle Type

1 gal/1000 ft² (chlorothalonil –

Daconil @ 1.8 oz/ M)

Num

ber

of le

sio

n C

ente

rs

Research Conducted for Rutgers Field Day

Impact of Water Volume and Nozzle Type on

Dollar Spot Control

0

10

20

30

AI Turbo XR Del. Untr.

Nozzle Type

2 gal/1000 ft²

(chlorothalonil - Daconil @ 1.8 oz/ M)

Num

ber

of le

sio

n C

ente

rs

Fidanza: Research Conducted for Rutgers Field Day - 2005

Impact of Simulated Rainfall

Dollar Spot Control: Rutgers• Five Fungicide Treatments

– Daconil Ultrex (1.8)

– Chipco 26GT (3.0)

– 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

– 24 hours after application

– None

EFFECT OF SIMULATED RAINFALL ON DOLLAR SPOT

CONTROL WITH Chipco 26GT 3 fl oz/1,000 sq ft

NO WATER immediately following

EFFECT OF SIMULATED RAINFALL ON DOLLAR SPOT

CONTROL WITH Chipco 26GT 3 fl oz/1,000 sq ft

UntreatedCHIPCO 0.5 INCHES FOUR

HOURS AFTER

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 4 hours after

treatment

What Impact of Water pH on

Fungicide Efficacy?

What is the Impact of pH on the Control of $-Spot?

• Most pesticides stable at pH 4 to 6

• Some fungicides “decompose” pH > 7.

-alkaline hydrolysis

-loss of pesticide efficacy

-examples:

-Polyoxin D (Endorse) fungicide

-Thiophanate methyl (Cleary’s 3336)

• Refer to product MSDS sheet for pH stability information

0

10

20

30

40

50

5 7 9 Untr.

Water Carrier pH

Dolla

r S

pot

(# Infe

ction C

ente

rs)

Rutgers, bentgrass green, July 19, 2007.

cc

Impact of Water pH on Dollar Spot Control

with Cleary 3336 50W @ 2 oz/M - 2007

b

a

0

2

4

6

8

10

4 5.5 7 8.5 10 Untr.

Water Carrier pH

Do

llar

Sp

ot

(# In

fec

tio

n C

en

ters

)

Bellewood GC, Agrostis fairway, July 11, 2006 Fidanza (PSU)

ddd

b

ab

a

Impact of Water pH on Dollar Spot Control

with chlorothalonil@ 4.3 kg ai/ ha - 2006

0

2

4

6

8

10

4 5.5 7 8.5 10 Untr.

Water Carrier pH

Dolla

r S

pot

(# Infe

ction C

ente

rs)

Bellewood GC, bentgrass fairway , July 11, 2006 Fidanza (PSU)

bbb b

Impact of Water pH on Dollar Spot Control

with propiconazole @ 0.23 kg ai/ ha - 2006

b

a

And Last but not Least,

Should You Rethink the Timing of Your

Fungicide Program for the Control of

Dollar Spot on Fairways?

#5 Fairway– No

early spring

applications

Photo July 7, 2004

Dr. Mike Boehm,

Ohio State Univ

#5 Fairway – with

one early spring

application

Photo July 7, 2004

Dr. Mike Boehm,

Ohio State Univ

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

● But this is very subjective – There must be a

better way.

New Research Study 2015-18 at Rutgers University

• Goal: to Develop BMPs for the Control of Dollar Spot on

fairway turf.

• Specific questions:

– What is the Influence of Host Tolerance (six CBG Cvrs) on

Dollar Spot Activity throughout the Season? (Study 1)

– Can Dollar Spot Outbreaks be Reliably Predicted? (Study 1)

– Can we Target Fungicide Applications with Models or Curative

Threshold Sprays to Reduce Fungicide Inputs? (Study 2)

Are There any Questions?

Rutgers Turfgrass Research Field Days: (turf.rutgers.edu)

- Aug. 2, 2016 (Golf Research – New Brunswick, NJ)

- Aug. 3, 2016 (Landscape Turf Res. – Adelphia, NJ)

Dr. Clarke and his graduate students and field crew