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