GCSAA Frank Wong Research update

4. Brown Ring Patch Symptoms on an Annual Bluegrass Green Photo by Pat Gradoville, Palos Verdes Golf Club

5. Rings start as small thin yellow circles a few inches in diameter that can expand to a foot or more in diameter. Rings can become orangish to brown and sunken if not treated. Rings can often merge together. Photo by Kent Davidson

6. Left untreated or treated too late, sunken dead areas may develop and take a long time to recover from Photo by Mike Wolpoff, Sea Cliff Country Club

7. Symptoms are very similar to Yellow Patch (R. cerealis), but Yellow Patch tends to occur at maximum daytime temperature below 65 deg F

8. Patches often have a greenish color that develops behind the yellow ring. These areas tend to be soft and sunken.

9. The mechanism of the greening is unknown; it may be a result of nitrogen being released from broken down thatch or increased microbial activity inside the affected areas

10. The pathogen, Waitea circinata var. circinata (stained red in this photo), colonizes leaves, sheaths and crowns.

11. The fungus also can colonize the thatch, upper root zone and soil

12. The fungus produces abundant mycelia in high humidity situations; this is called the ‘Don King’ appearance of the fungus. Photo by Larry Stowell

13. The pathogen degrades thatch, resulting in sunken rings on greens Photo by Mike Wolpoff, Sea Cliff Country Club

14. Rings expand a few inches in size a week – photos are taken 1 week apart from each other. This suggests that the disease more dynamic than previously thought.

15. The brown ring patch is rare on creeping bentgrass in the U.S. Rings that develop on creeping bentgrass tend to have a brown color. Photos taken from the Color Atlas Of Turfgrass Diseases by James B. Beard & Toshhikazu Tani (2002)

16. Brown Ring Patch on rough bluegrass also appears more reddish to brown in color

17. Distribution of W. circinata var circinata in the U.S.

19. Disease Teleomorph Name (Sexual State) Anamorph name (Asexual State) Optimal Temp. Range (Max. Daytime Temps.) Typical hosts Yellow Patch Ceratobasidium cereale Rhizoctonia cerealis 50-65ºF Cool & warm season species Brown Patch of Cool Season Turf Thanatephorus cucumeris Rhizoctonia solani 77-90ºF All cool season species Brown Patch of Warm Season Turf (Large Patch) Thanatephorus cucumeris Rhizoctonia solani 60-77ºF All warm season species Leaf and Sheath Spot (High Temperature Brown Patch) Waitea circinata var oryzae Rhizoctonia oryzae 83-97ºF Cool & warm season species Waitea circinata var zeae Rhizoctonia zeae 83-97ºF Brown Ring Patch (Waitea Patch) Waitea circinata var circinata none 77-86ºF Annual Bluegrass, Creeping Bentgrass, Rough Bluegrass

20. Brown Ring Patch Trials at Torrey Pines Golf Course 2008 (North Course)

27. Digital disease analysis using Sigma Plot software and images taken with a Canon D70 camera

29. Nitrogen effects on disease severity

30. Nitrogen & Primo MAXX effects

31. Nitrogen vs Nitrogen + Primo

33. water nitrate + Primo MAXX wk 1 ammonium + Primo MAXX urea + Primo MAXX wk 3 wk 5 water + Primo MAXX

38. Heritage Heritage + N Heritage + N + Primo MAXX wk 1 wk 2 wk 3 wk 4

39. Nitrogen, Primo & Heritage effects a a b b b b a Disease severity

41. Materials Under Trial Pt 1

42. Materials Under Trial Pt 2

43. Trial 1: Effects of DMIs and DMI mixtures on brown ring patch

45. C B A

46. B A C

47. B C A

48. B C A

49. B C A

50. Trial 2: Effects of Rhizoctonia fungicides on brown ring patch

51. A C B

52. D B C A

53. A B C

54. A C B

55. A C B

56. Trial 3: Effects of repeated QoI fungicide applications on brown ring patch

58. C B A

59. C B A

60. C B A

61. C A B