Thatch collapse is a disease of warm and cool-season turfgrasses and is caused by Sphaerbolus stellatus. The disease has been found throughout the United States as well as in Europe, Australia and New Zealand.

1. Amy M. Baetsen|| Dr. John E. Kaminski
The Pennsylvania State University
Thatch Collapse: A New Disease of Golf Course Turf

2. THATCH COLLAPSE
• First Identified on Fine Leaf Fescue in
Northern Scotland Summer 2010
– May 2011 Issue of Golf Course Management
• Symptoms Observed at Penn State Research
Facility Fall 2010

3. THATCH COLLAPSE
• Believed to be Caused by a Basidiomycete

4. OVERVIEW OF BASIDIOMYCETES
• Yellow Ring (Trechispora alnicola)
– Kentucky Bluegrass
• Superficial Fairy Ring (T. cohaerens and
Coprinus kubickae)
– Bentgrass, Fescue and Poa
• White Blight (Melanotus phillipsii)
– Mainly Fescue but on Bentgrass, Ryegrass and Poa

5. OVERVIEW OF BASIDIOMYCETES
• Fairy Ring (Various Species)
– Type I, II, and III

6. OVERVIEW OF BASIDIOMYCETES
• Localized Dry Spot (Various Species)
• Thatch Collapse (Unidentified)

7. THATCH COLLAPSE SYMPTOMS
• Different From Other Basidiomycetes Diseases
– Sunken Circular Patches
– Darker Green Turf Within Patches
– Mycelium May be Present
– On Greens, Tees and Fairways

10. THATCH DEGRADATION RESULTING IN
SUNKEN PATCHES

12. WHITE MYCELIUM IN THATCH

13. THATCH COLLAPSE
• PATHOGEN: Unknown Basidiomycete
• HOSTS: Creeping Bentgrass, Velvet Bentgrass,
others?
• SYMPTOMS: Sunken Green Circular Patches (3” to
1’)
• SIGNS: Mycelium in Thatch and Foliage Following
Incubation

14. SINCE THEN SYMPTOMS HAVE BEEN
REPORTED IN…
California
Ohio
Michigan
Montana
Pennsylvania
South Dakota
Australia
New Zealand

15. HAS OCCURRED ON GOLF COURSES GLOBALLY
PhotocourtesyMeganCushnahan
New Zealand
Michigan, USA

17. GENERAL SYMPTOMS DESCRIBED
• Circular Patches 6-18 Inches in Diameter
With an Irregular Border
– Darker Green Turf from Thatch Degradation
– White Mycelia Present on Thatch Layer
– Orange Hue within Infested Thatch
• Symptoms Not Limited to One Turf Species
– Warm and Cool-Season Turfgrasses

18. THATCH COLLAPSE SAMPLES WERE INCUBATED
• Consistent Development of Fruiting Bodies
Similar to the Artillery Fungus (Sphaerobolus
stellatus)

19. SPHAEROBOLUS STELLATUS
ImageCourtesyD.Davis,PennState
ImageCourtesyD.Davis,PennState
• White Rot Fungi
• Normally Found on Mulch

20. • Contains Potential
Enzymes to
Degrade Organic
Matter (Valentin et
al., 2009)
Valentin, L., B. Kluczek-Turpeinen, P. Oivanen, A.
Hatakka, K. Steffen and M Tuomela. 2009.
Evaluation of basidiomycetous fungi for pretreatment
of contaminated soil. Journal of Chemical
Technology and Biotechnology 84:851-858

22. © Ron Wolf

23. ImageCourtesyD.Davis,PennState
SPHAEROBOLUS STELLATUS
ImageCourtesyofSteveYoung,MI

25. OBJECTIVES OF RESEARCH
1. Understand Causal Organism
A. Identify Organism by DNA Sequencing
B. Complete Koch’s Postulates
C. Measure Growth Rates
2. Initiate Management Strategies

26. CONFIRMATION OF S. STELLATUS
• Completed DNA Sequencing
• The DNA Sequences Were a 99% Match for
California, Michigan, South Dakota and New
Zealand to Known S. stellatus From Mulch.

27. BUT DOES S. STELLATUS CAUSE THATCH
COLLAPSE?
• Completed Koch’s Postulates
– Association
– Isolation
– Inoculation and Symptoms Development
– Re-Isolation

28. KOCH’S POSTULATES
• Incubated 12 Mature
Penn ‘A-1’ Creeping
Bentgrass Plugs at 12°C
and 24 hr Light for 6
Weeks
• Plugs Inoculated with
– Sterilized Thatch
– No Thatch
– S. stellatus Infested Thatch

29. KOCH’S POSTULATES
• Data Collection:
– Compressed Thatch Depth Measurement
– Percent Total Organic Matter
– Means Separated at P < 0.05 According to the Least
Significant Difference Test

30. FOUND S. STELLATUS CAUSES…
• Decreased Thatch Layer from 2.0 cm to 1.45 cm
– Significant Reduction of 28%
A*
A
B
0
0.5
1
1.5
2
2.5
Thatchdepth(cm)
Treatments
Compressed Thatch Depth
Un-inoculuated
control
Sterilized thatch
inoculum
S. stellatus
infested inoculum
*Combined means followed by the same letter are not significantly
different according to LSD test at α = 0.05

31. FOUND S. STELLATUS CAUSES…
• Significant Reduction of Organic Matter 21%
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
OrganicMatter(%)
Treatments
Organic Matter Content
Control
S. stellatus infested
A*
B
*Combined means followed by the same letter are not significantly
different according to LSD test at α = 0.05.

33. KOCH’S POSTULATES
• S. stellatus was Re-isolated from Infested Plugs

34. Association Isolation
Re-inoculationRe-isolation

35. GROWTH OF S. STELLATUS
• Growth Temperatures
– In Vitro Growth of S. stellatus
– Six Temperatures (5, 10, 15, 21, 25 and 30°C)
– Radial Mycelia Growth Measured

36. BIOLOGY OF S. STELLATUS
• S. stellatus Optimal Daily Growth Rate at 21-
30°C (70-86°F)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
5 10 15 21 25 30
AverageDailyGrowthRate(mm)
Temperature °C
S. stellatus Growth Rate
CA
MI
SD

37. SUMMARY
• Thatch Collapse Symptoms Observed Globally
• S. stellatus Shown to Degrade Organic Matter
– Decreased Thatch Depth 28%
– Total Organic Matter Reduced 21%
• Optimal Growth at 70-86°F

38. FLIED TRIALS FOR MANAGEMENT
• Plots Inoculated with S. stellatus Infested
Thatch in May 2012
• Developed Symptoms June 2012

40. FLIED TRIALS FOR MANAGEMENT
• Ongoing Trials
– Influence of Nitrogen Sources
– Preventive and Curative Fungicidal Control
• Data Collected Through the 2013 Season

41. Influence of Nitrogen Sources
0
1
2
3
4
5
6
7
8
9
22-Jun
29-Jun
6-Jul
13-Jul
20-Jul
27-Jul
3-Aug
10-Aug
17-Aug
24-Aug
31-Aug
7-Sep
14-Sep
21-Sep
28-Sep
5-Oct
12-Oct
19-Oct
26-Oct
2-Nov
9-Nov
PatchDiameter(cm)
Time
Patch Development Summer 2012
Ammonium Nitrate
Calcium Nitrate
Potassium Nitrate
Ammonium Sulfate
Urea
20-20-20

42. CURRENT MANAGEMENT SUGGESTIONS
• Preventive:
– Manage Thatch Accumulation
• Verticut
• Aerify
• Topdress Regularly

43. CURRENT MANAGEMENT SUGGESTIONS
• After Symptoms Develop
– Topdress for Even Playing Surface
• Fungicides?
Common Name Trade Name EC50 (ppm)
Polyoxin-D Endorse 2.5 WP 0.201
Azoxystrobin Heritage 50WG 0.432
Pyraclostrobin Insignia 20WG 0.540
Triademifon Bayleton 50DF 0.597
Tebuconazole Lynx 45WP (Torque) 0.828
Chlorothalonil Daconil Ultrex 82.5 WDG 1.258
Flutolanil Prostar 70WP 1.951
Fidanza M. A. and D. D. Davis 2009. In vitro screening of control artillery fungi. J. Environ. Hort. 27:155-158.

44. CONCLUSIONS
• Thatch Collapse is a New Problem in Turf
• Sphaerobolus stellatus is a Casual Agent
– Grows Optimally at 70 to 86°F
• Possible Management Strategies
– Endorse/Affirm, ProStar, Heritage
• Tank Mix with Wetting Agent
• Water-in
– Topdress Regularly
• Treat Like Fairy Ring

45. THATCH COLLAPSE RESEARCH
• Biology and Epidemiology
• Fungicide Evaluations
• Cultural Management Practices
• Thatch Degrading Enzymes

46. THATCH DEGRADING ENZYMES
• Sidhu et al., 2012 Found Applying Fungal
Laccase Reduced Thatch Layer
• S. stellatus Has Similar Enzyme Production
• Biodethatching?
Sidhu S. S., Q. Huang, R. N. Carrow and P. L. Raymer. 2012. Use of fungal laccases to
facilitate biodethatching: a new approach. Hort Science 47:1536-1542.

49. Amy M. Baetsen|| Dr. John E. Kaminski
The Pennsylvania State University
Thatch Collapse: A New Disease of Golf Course Turf