Managing Diseases in Warm-Season Landscapes

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Moore County T&O Conference
March 1, 2011

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  • Managing Diseases in Warm-Season Landscapes

    1. 1. Disease Management in Warm-Season TurfgrassesLane TredwayAssociate Professor and Extension SpecialistDepartment of Plant PathologyNorth Carolina State University
    2. 2. Few disease problems occur onwarm-season turfgrasses.
    3. 3. They are most susceptible in fall, winter, and spring.
    4. 4. What are the keys to successful disease management?
    5. 5. Provide a good growing environment.
    6. 6. Manage the turf properly.
    7. 7. CarolinaLawnsA Guide to MaintainingQuality Turf in the Landscape 1
    8. 8. Don’t over-irrigate!
    9. 9. Turf Irrigation Management System http://www.turffiles.ncsu.edu/tims
    10. 10. Diagnose problems accurately.
    11. 11. Disease diagnosis is troubleshooting
    12. 12. Submit samples for disease diagnosis.
    13. 13. NC State Turf Diagnostics Lab ncstateturfdiagnostics.com
    14. 14. Disease Diagnosis Decision Aidwww.turffiles.ncsu.edu/diseaseID
    15. 15. Select the right fungicide.
    16. 16. How do you choose a fungicide?
    17. 17. How do you choose a fungicide?Heritage (0.2 oz, 28 day) Eagle (1.2 oz, 14 day)
    18. 18. Fungicide SelectionReferences• Product Labels• Pest Control for Professional Turf Managers• TurfFiles Disease Profiles• TurfFiles Fungicide Selection Tool
    19. 19. Diseases of Centipedegrass • large patch • dollar spot • fairy ring
    20. 20. Diseases of St. Augustinegrass • large patch • gray leaf spot • take-all root rot
    21. 21. Diseases of Zoysiagrass • large patch • dollar spot • rust • Curvularia blight • spring dead spot • fairy ring
    22. 22. Though caused by the same fungus, brown patch and largepatch are very different diseases.
    23. 23. Though caused by the same fungus, brown patch and largepatch are very different diseases.
    24. 24. Large patch causes rotting of the leaf sheaths beginning in late symmer, which leads to foliar dieback in fall or spring.
    25. 25. Large patch is the most severe disease of zoysiagrass
    26. 26. Centipedegrass is most susceptible to large patch
    27. 27. Large patch rarely causes long-term damage to bermudagrass.
    28. 28. 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
    29. 29. What is wrong with this picture?
    30. 30. Large patch is active when soil temperatures are below 70ºF
    31. 31. 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
    32. 32. provide outstanding control ofQoI Fungicides Rhizoctonia diseases
    33. 33. Fungicides for Large Patch ControlBenzimidazoles 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
    34. 34. 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, KSTreatments applied Oct 8Data collected Apr 24
    35. 35. Untreated Bayleton (2 oz)
    36. 36. Spring dead spot symptoms appear in spring as thebermudagrass resumes growth.
    37. 37. Spring Dead Spot Attacks All Below-Ground TissuesInjury to roots, stolons, and rhizomes renders the bermudagrassmore prone to winter injury.
    38. 38. 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
    39. 39. Regular aerification reduces spring dead spot development
    40. 40. Recovery from spring dead spot is very slow....
    41. 41. 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
    42. 42. Spring dead spot can be controlled with fungicides
    43. 43. Rubigan (6 + 6 fl oz) Untreated Control
    44. 44. 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
    45. 45. Two species of Ophiosphaerella cause spring dead spot
    46. 46. 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 2009Nitrogen treatments applied monthy from May through August in 2006, 2007, and 20081 lb N per 1000 ft2 per application; 4 lbs N per 1000 ft2 per year
    47. 47. Urea
    48. 48. Ammonium Sulfate
    49. 49. Calcium Nitrate
    50. 50. Gray leaf spot of St. Augustinegrass.
    51. 51. Gray leaf spot is most severe in St. Augustinegrass that isgrowing slowly or is mowed infrequently.
    52. 52. Gray leaf spot rarely causes significant damage to well-managedSt. Augustinegrass.
    53. 53. 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

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