Disease management in warm-season turfgrasses requires providing a good growing environment, properly managing the turf, and accurately diagnosing any problems. Some key diseases include large patch, dollar spot, and fairy ring. Large patch is most active below 70°F and favors saturated soils with excessive nitrogen or thatch. Preventative fungicide applications in fall can provide good control. Spring dead spot damages roots and rhizomes over winter and recovery is slow. Aerifying, moderate nitrogen, and fall fungicide applications can help control it. Gray leaf spot favors warm temperatures and leaf wetness on stressed or slowly growing St. Augustinegrass.

1. Disease Management in Warm-
Season Turfgrasses
Lane Tredway
Associate Professor and Extension Specialist
Department of Plant Pathology
North Carolina State University

2. Few disease problems occur on
warm-season turfgrasses.

3. They are most susceptible in fall, winter, and spring.

5. What are the keys to successful
disease management?

6. Provide a good growing environment.

7. Manage the turf properly.

8. Carolina
Lawns
A Guide to Maintaining
Quality Turf in the Landscape
1

9. Don’t over-irrigate!

10. Turf Irrigation Management System
http://www.turffiles.ncsu.edu/tims

11. Diagnose problems
accurately.

12. Disease diagnosis is
troubleshooting

13. Submit samples for disease diagnosis.

14. NC State Turf Diagnostics Lab
ncstateturfdiagnostics.com

15. Disease Diagnosis Decision Aid
www.turffiles.ncsu.edu/diseaseID

16. Select the right fungicide.

17. How do you choose a fungicide?

18. How do you choose a fungicide?
Heritage (0.2 oz, 28 day) Eagle (1.2 oz, 14 day)

19. Fungicide Selection
References
• Product Labels
• Pest Control for Professional
Turf Managers
• TurfFiles Disease Profiles
• TurfFiles Fungicide Selection
Tool

20. Diseases of Centipedegrass
• large patch
• dollar spot
• fairy ring

21. Diseases of St. Augustinegrass
• large patch
• gray leaf spot
• take-all root rot

22. Diseases of Zoysiagrass
• large patch
• dollar spot
• rust
• Curvularia blight
• spring dead spot
• fairy ring

23. Though caused by the same fungus, brown patch and large
patch are very different diseases.

24. Though caused by the same fungus, brown patch and large
patch are very different diseases.

25. Large patch causes rotting of the leaf sheaths beginning in late
symmer, which leads to foliar dieback in fall or spring.

26. Large patch is the most severe disease of zoysiagrass

27. Centipedegrass is most susceptible to large patch

28. Large patch rarely causes long-term damage to bermudagrass.

29. Conditions favoring large patch development
• infection occurs when soil temperatures are below 70°F
• saturated thatch/soil
• excessive nitrogen during periods of slow growth
• excessive thatch accumulation
• low mowing heights

30. What is wrong with this picture?

31. Large patch is active when soil temperatures are below 70ºF

32. Controlling Large Patch with Fungicides
• preventative applications most effective
• initiate in fall when soil temperatures decline below 70°F
• one properly timed application will provide good control in
most landscape situations
• in severe cases, repeat applications on 4 to 6 week intervals
may be necessary
• curative applications help to reduce further spread, but
recovery will be slow

33. provide outstanding control of
QoI Fungicides Rhizoctonia diseases

34. Fungicides for Large Patch Control
Benzimidazoles Contacts
• thiophanate-methyl (3336) • chlorothalonil (Daconil)***
QoI • fludioxonil (Medallion)
• azoxystrobin (Heritage) • mancozeb (Fore)
• fluoxystrobin (Disarm) • polyoxin D (Endorse)
• pyraclostrobin (Insignia) Dicarboxamides
• trifloxystrobin (Compass) • iprodione (Chipco 26GT)***
DMIs • vinclozolin (Curalan)***
• fenarimol (Rubigan) Benzamides
• myclobutanil (Eagle) • flutolanil (Prostar)
• propiconazole (Banner)
• triadimefon (Bayleton)
***Not labeled for application to landscape
turfgrasses

35. Large patch control in ‘Meyer’ zoysiagrass
Untreated
Banner Maxx (4 fl oz)
Heritage (0.4 oz)
Bayleton (1 oz)
Prostar (2.2 oz)
0 5 10 15 20 25 30 35
Large Patch Incidence (%)
Lawrence, KS
Treatments applied Oct 8
Data collected Apr 24

36. Untreated Bayleton (2 oz)

37. Spring dead spot symptoms appear in spring as the
bermudagrass resumes growth.

38. Spring Dead Spot Attacks All Below-Ground Tissues
Injury to roots, stolons, and rhizomes renders the bermudagrass
more prone to winter injury.

39. Conditions Favoring Spring Dead Spot Development
• any factor that restricts root growth
• soil compaction
• excessive thatch
• wet soils
• any factor that reduces winter hardiness
• excessive nitrogen in fall
• potassium deficiency
• wet soils

40. Regular aerification reduces spring dead spot development

41. Recovery from spring dead spot is very slow....

42. Speeding Spring Dead Spot Recovery
• avoid use of DNA herbicides in spring
- dithiopyr (Dimension)
- pendimethalin (Pendulum)
• aerify or spike affected areas every two weeks
• apply light and frequent irrigation
• apply 1 lb N per 1000 per month from May to Sept

43. Spring dead spot can be controlled with fungicides

44. Rubigan (6 + 6 fl oz) Untreated Control

45. Keys to Successful Control of SDS
• commit to implementing program for at least 3 years
• map affected areas in spring for treatment
• select an effective product
• apply preventatively in fall when soil temperatures
are between 60˚F and 80˚F
• water-in immediately with 1/8” to 1/4” of irrigation

46. Two species of Ophiosphaerella cause spring dead spot

47. Nitrogen Source Influences Spring Dead Spot
Dvelopment
Sulfur Coated Urea Calcium Nitrate Urea Ammonium Sulfate
Spring Dead Spot Index (diameter*incidence)
90 25
a
O. herpotricha a O. korrae
a
75 a
20 a
60
a 15
45 a a
a b a
a
10
30 ab
b ab
5
15 b a
b a a
c a b b
0 0
2007 2008 2009 2007 2008 2009
Nitrogen treatments applied monthy from May through August in 2006, 2007, and 2008
1 lb N per 1000 ft2 per application; 4 lbs N per 1000 ft2 per year

48. Urea

49. Ammonium Sulfate

50. Calcium Nitrate

51. Gray leaf spot of St. Augustinegrass.

52. Gray leaf spot is most severe in St. Augustinegrass that is
growing slowly or is mowed infrequently.

53. Gray leaf spot rarely causes significant damage to well-managed
St. Augustinegrass.

54. Conditions Favoring Gray Leaf Spot
• 75ºF to 95ºF
• Extended periods of leaf wetness
• Most severe in newly established plantings
• High mowing heights and/or infrequent mowing
• Slowly growing turf
• Turf stressed by nutrient deficiency, drought, or traffic