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Impact of Fertilization Programs and Preventive Fungicides on Spring Dead Spot

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Lane Tredway
Southeastern Turf Conference
Tifton, GA
May 3, 2011

Published in: Education, Business, Technology
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Impact of Fertilization Programs and Preventive Fungicides on Spring Dead Spot

  1. 1. Impact of Fertilization Programs and PreventiveFungicide Applications On Spring Dead Spot inHybrid BermudagrassL.P. Tredway, M.D. Soika, and E.L. ButlerDepartment of Plant PathologyNorth Carolina State University NC STATE TURFGRASS PATHOLOGY
  2. 2. Spring Dead Spot• most severe disease of hybrid bermudagrasses in transition zone climates• preventive fungicides erratic in their performance, and often not economical• influence of soil properties and fertilization programs not well understood
  3. 3. Spring Dead Spot• caused by root, rhizome, and stolon infections by Ophiosphaerella species• fungal infections reduce bermudagrass tolerance to freezing temperatures• ‘patch diseases’ typically enhanced by high soil pH• fall potassium applications often recommended to improve cold tolerance
  4. 4. Damage is often most severe on north-facing slopes...
  5. 5. Why is the damage more severe surrounding this green?
  6. 6. Regular aerification reduces spring dead spot development
  7. 7. Varieties with Improved Resistance to SDS • Guymon • Midiron • Midlawn • Midfield • Mirage • Patriot • Sundevil • Tifsport
  8. 8. Recovery from spring dead spot is very slow....
  9. 9. Speeding Spring Dead Spot Recovery• avoid use of DNA herbicides in spring - prodiamine (Barricade) - dithiopyr (Dimension)• 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
  10. 10. How does soil pH influence take-all patch development?• the take-all patch pathogen, Gaeumannomyes graminis var. avenae, facilitates infection by sequestering Mn on the root surface• lower pH increases the solubility of Mn in the soil, allowing the root to better resist infection• lower pH also increases population of fluorescent Pseudomonads, which produce antifungal compounds on the root surface
  11. 11. How does nitrogen source influence soil pH?• calcium nitrate increases pH, whereas Soil Root ammonium sulfate reduces it• when the root absorbs a nitrate ion NO3- (NO3-), a hydroxyl ion (OH-) is released, therefore increasing rhizosphere pH OH-• when the root absorbs an ammonium ion (NH4+), a hydrogen ion (H+) is released, therefore reducing rhizosphere pH NH4+ H+• sulfate (SO4-) and calclium (Ca+) have little to no effect on soil pH
  12. 12. Previous Research: Fertilization and Spring Dead Spot• Dernoeden, Crahay and Davis (1991) studied impact of nitrogen source and potassium on spring dead spot development • in greenhouse, ammonium sulfate or potassium chloride increased bermudagrass survival after inoculation with O. korrae • in field studies, ammonium sulfate, ammonium chloride, and ammonium chloride + potassium chloride provided up to 46% suppression • significant correlation between SDS and soil pH detected
  13. 13. Previous Research: Fertilization and Spring Dead Spot• McCarty, Lucas and DiPaola (1992) investigated the effect of fall nitrogen and potassium applications • late fall applications of sulfur coated urea (98 kg N/ha) or potassium sulfate (269 kg K/ha) significantly increased SDS severity• Vincelli, Doney and Powell (1994) evaluated sulfur, lime, and KCl • significant suppression of O. herpotricha from applications of elemental sulfur at rates of from 6.9 to 10.4 lbs/M • concomitant with reduction in soil pH
  14. 14. Spring dead spot can be controlled with fungicides
  15. 15. Fungicides for Spring Dead Spot ControlBenzimidazoles thiophanate-methyl (3336, Systec, T-Storm)DMIs fenarimol (Rubigan) myclobutanil (Eagle, Immunox) propiconazole (Banner Maxx, Propiconazole Pro, Savvi, Spectator) tebuconazole (Torque) triticonazole (Trinity, Triton)QoIs azoxystrobin (Heritage) fluoxastrobin (Disarm) pyraclostrobin (Insignia)Premixes azoxystrobin + propiconazole (Headway) fluoxastrobin + myclobutanil (Disarm M)
  16. 16. Rubigan (6 + 6 fl oz) Untreated Control
  17. 17. O. herpotricha O. korraeSpring dead spot is caused by three Do these species respond to management practices species of Ophiosphaerella similarly?
  18. 18. Research Objectives: Spring Dead SpotManagement
  19. 19. Research Objectives: Spring Dead SpotManagement1. Determine the effects of nitrogen source and fall fertilization practices on spring dead spot development in bermudagrass fairways/athletic fields
  20. 20. Research Objectives: Spring Dead SpotManagement1. Determine the effects of nitrogen source and fall fertilization practices on spring dead spot development in bermudagrass fairways/athletic fields2. Evaluate fungicides for preventive control of spring dead spot in inoculated plots
  21. 21. Research Objectives: Spring Dead SpotManagement1. Determine the effects of nitrogen source and fall fertilization practices on spring dead spot development in bermudagrass fairways/athletic fields2. Evaluate fungicides for preventive control of spring dead spot in inoculated plots3. Compare and contrast the response of O. korrae and O. herpotricha to the above management practices
  22. 22. Bermudagrass Establishment and Inoculation• 10,000 ft2 plot established with ‘Tifway’ sprigs on Appling fine sandy loam• 5’ x 10’ plots inoculated with O. korrae and O. herpotricha in October 2004• at each inoculation point, 10 cc of infested ryegrain was placed underneath a 2”- deep cup-cutter plug
  23. 23. Bermudagrass Establishment and Inoculation• 10,000 ft2 plot established 1.52 m with ‘Tifway’ sprigs on Appling fine sandy loam Ok Oh• 5’ x 10’ plots inoculated with O. korrae and O. herpotricha in October 2004 Ok Oh 3.05 m• at each inoculation point, 10 cc of infested ryegrain was placed underneath a 2”- Ok Oh deep cup-cutter plug
  24. 24. Bermudagrass Establishment and Inoculation• 10,000 ft2 plot established with ‘Tifway’ sprigs on Appling fine sandy loam• 5’ x 10’ plots inoculated with O. korrae and O. herpotricha in October 2004• at each inoculation point, 10 cc of infested ryegrain was placed underneath a 2”- deep cup-cutter plug
  25. 25. Bermudagrass Establishment and Inoculation• 10,000 ft2 plot established with ‘Tifway’ sprigs on Appling fine sandy loam• 5’ x 10’ plots inoculated with O. korrae and O. herpotricha in October 2004• at each inoculation point, 10 cc of infested ryegrain was placed underneath a 2”- deep cup-cutter plug
  26. 26. Bermudagrass Establishment and Inoculation• 10,000 ft2 plot established with ‘Tifway’ sprigs on Appling fine sandy loam• 5’ x 10’ plots inoculated with O. korrae and O. herpotricha in October 2004• at each inoculation point, 10 cc of infested ryegrain was placed underneath a 2”- deep cup-cutter plug
  27. 27. Experiment 1: Nitrogen Source and Fall FertilizationNitrogen Sources (Main Plots) Fall Fertilizers (Subplots)• 1 lb N applied 4X per year • applied in Sept and/or Oct each 1. ammonium sulfate year 2. calcium nitrate 1. dolomitic lime (10 lb, 1 app) 3. sulfur coated urea 2. elemental sulfur (2 lb, 1 app) 4. urea 3. gypsum (10 lb, 1 app) 4. potassium chloride (1 lb, 1- Split-plot, randomized complete block app) with 4 replications 5. potassium chloride (0.5 lb, 2- Treatments initiated in May 2006 apps)- Applied to same plots in 2006, 2007, 6. potassium chloride (1 lb, 2 and 2008 apps)- entire study fertilized with 0.33 lb P and 0.66 lb K at time of each N application
  28. 28. Experiment 2: Preventive Fungicide ApplicationsFungicide Treatments Application Details 1. Banner Maxx (4 fl oz, 2 apps) • randomized complete block with 4 2. Eagle (2.4 fl oz, 2 apps) replications 3. Headway (3 fl oz, 2 apps) • fungicide treatments were applied in September and/or October in 4. Heritage (0.4 oz, 2 apps) 2006, 2007, and 2008 5. Lynx (2 fl oz, 2 apps) • applications made in water 6. Rubigan (6 fl oz, 1 app) equivalent to 5 gallons per 1000 ft2 7. Rubigan (4 fl oz, 2 apps) • CO2 powered sprayer at 40 psi 8. Rubigan (6 fl oz, 2 apps) using TeeJet 8004 nozzles
  29. 29. Assessment of Spring Dead Spot Severity• average diameter of each patch recorded at 100% greenup• digital image of each plot captured from overhead for digital analysis of disease incidence• SEVERITY INDEX (Average Patch Diameter x Disease Incidence) calculated separately for O. korrae and O. herpotricha
  30. 30. Assessment of Spring Dead Spot Severity• average diameter of each patch recorded at 100% greenup• digital image of each plot captured from overhead for digital analysis of disease incidence• SEVERITY INDEX (Average Patch Diameter x Disease Incidence) calculated separately for O. korrae and O. herpotricha
  31. 31. Assessment of Spring Dead Spot Severity• average diameter of each patch recorded at 100% greenup• digital image of each plot captured from overhead for digital analysis of disease incidence• SEVERITY INDEX (Average Patch Diameter x Disease Incidence) calculated separately for O. korrae and O. herpotricha
  32. 32. Assessment of Spring Dead Spot Severity• average diameter of each patch recorded at 100% greenup• digital image of each plot captured from overhead for digital analysis of disease incidence• SEVERITY INDEX (Average Patch Diameter x Disease Incidence) calculated separately for O. korrae and O. herpotricha
  33. 33. Additional Data Collection (Fertility Study Only)• leaf tissue samples collected from each plot with a reel mower in mid- September 2006, 2007 and 2008 for nutrient analysis• soil samples collected from each plot in December 2006, 2007 and 2008 for measurement of soil pH using 1:1 soil:water ratio
  34. 34. ANOVA: Nitrogen Source and Fall Fertilization p-valuesSource df 2007 2008 2009N Source 3 0.0506 0.0032 <0.0001Fall Nutrients 6 0.545 0.3794 0.4150Pathogen Species 1 <0.0001 <0.0001 <0.0001Block 3 <0.0001 0.0002 0.0115N*Fall 18 0.9646 0.8604 0.3879N*Species 3 0.02 0.0062 <0.0001Fall*Species 6 0.4647 0.3706 0.2639N*Fall*Species 18 0.9936 0.952 0.3840
  35. 35. Impact of Nitrogen Source on O. herpotricha 90 Sulfur Coated Urea a a Calcium Nitrate a 75 Urea aSpring Dead Spot Index Ammonium Sulfate (diameter*incidence) 60 a a 45 a a a b a a b a 30 ab b ab b 15 b b b b 0 c c 2007 2008 2009 Waller-Duncan k-ratio t- test
  36. 36. Impact of Nitrogen Source on O. korrae 30 Sulfur Coated Urea Calcium Nitrate a 25 Urea aSpring Dead Spot Index Ammonium Sulfate (diameter*incidence) a 20 a a a 15 a a a a b a 10 ab b ab 5 a ab a b a b b 0 c 2007 2008 2009 Waller-Duncan k-ratio t- test
  37. 37. Calcium Nitrate Ammonium Sulfate Urea May 2009
  38. 38. Pearson Correlation Coefficients log (spring dead spot index)Factor O. herpotricha O. korrae r=0.31 r=-0.45soil pH p=<0.0001 p<0.0001 r=-0.10 r=-0.07 N p=0.88 p=0.3080 r=0.21 r=0.02 P p=0.0016 p=0.7748 r=0.08 r=0.04 K p=0.2448 p=0.5779 r=0.21 r=-0.36 Ca p=0.0014 p=<0.0001 r=0.23 r=0.07 Mg p=0.0006 p=0.3309 r=0.11 r=0.04 S p=0.0996 p=0.5471 r=-0.08 r=-0.06 Fe p=0.2428 p=0.4051 r=-0.29 r=0.28 Mn p=<0.0001 p=<0.0001 r=-0.005 r=0.24 Zn p=0.9443 p=0.0003 r=0.06 r=0.17 Cu p=0.3665 p=0.0123
  39. 39. Pearson Correlation Coefficients log (spring dead spot index)Factor O. herpotricha O. korrae r=0.31 r=-0.45soil pH p=<0.0001 p<0.0001 r=-0.10 r=-0.07 N p=0.88 p=0.3080 r=0.21 r=0.02 P p=0.0016 p=0.7748 r=0.08 r=0.04 K p=0.2448 p=0.5779 r=0.21 r=-0.36 Ca p=0.0014 p=<0.0001 r=0.23 r=0.07 Mg p=0.0006 p=0.3309 r=0.11 r=0.04 S p=0.0996 p=0.5471 r=-0.08 r=-0.06 Fe p=0.2428 p=0.4051 r=-0.29 r=0.28 Mn p=<0.0001 p=<0.0001 r=-0.005 r=0.24 Zn p=0.9443 p=0.0003 r=0.06 r=0.17 Cu p=0.3665 p=0.0123
  40. 40. Pearson Correlation Coefficients log (spring dead spot index)Factor O. herpotricha O. korrae r=0.31 r=-0.45soil pH p=<0.0001 p<0.0001 r=-0.10 r=-0.07 N p=0.88 p=0.3080 r=0.21 r=0.02 P p=0.0016 p=0.7748 r=0.08 r=0.04 K p=0.2448 p=0.5779 r=0.21 r=-0.36 Ca p=0.0014 p=<0.0001 r=0.23 r=0.07 Mg p=0.0006 p=0.3309 r=0.11 r=0.04 S p=0.0996 p=0.5471 r=-0.08 r=-0.06 Fe p=0.2428 p=0.4051 r=-0.29 r=0.28 Mn p=<0.0001 p=<0.0001 r=-0.005 r=0.24 Zn p=0.9443 p=0.0003 r=0.06 r=0.17 Cu p=0.3665 p=0.0123
  41. 41. Pearson Correlation Coefficients log (spring dead spot index)Factor O. herpotricha O. korrae r=0.31 r=-0.45soil pH p=<0.0001 p<0.0001 r=-0.10 r=-0.07 N p=0.88 p=0.3080 r=0.21 r=0.02 P p=0.0016 p=0.7748 r=0.08 r=0.04 K p=0.2448 p=0.5779 r=0.21 r=-0.36 Ca p=0.0014 p=<0.0001 r=0.23 r=0.07 Mg p=0.0006 p=0.3309 r=0.11 r=0.04 S p=0.0996 p=0.5471 r=-0.08 r=-0.06 Fe p=0.2428 p=0.4051 r=-0.29 r=0.28 Mn p=<0.0001 p=<0.0001 r=-0.005 r=0.24 Zn p=0.9443 p=0.0003 r=0.06 r=0.17 Cu p=0.3665 p=0.0123
  42. 42. Prevention of Spring Dead Spot with Fungicides• significant fungicide effects were Rubigan (6 fl oz, 1X) Untreated detected in 2007 (p=0.0017) and 2008 (p=0.0098), but not in 2009 (p=0.1264)• a significant fungicide x species interaction was detected in 2007 (p=0.0042) due to low index values induced by O. korrae• no significant fungicide x species interaction was detected in 2008 (p=0.1111) or 2009 (p=0.0727)
  43. 43. Prevention of Spring Dead Spot with Fungicides Spring Dead Spot Index (diameter*incidence) Dunnett’s Test
  44. 44. Prevention of Spring Dead Spot with Fungicides Banner Maxx (4 fl oz, 2X) Eagle (2.4 fl oz, 2X) Headway (3 fl oz, 2X) Heritage (0.4 oz, 2X) Lynx (2 fl oz, 2X) Rubigan (6 fl oz, 1X) Rubigan (4 fl oz, 2X) Rubigan (6 fl oz, 2X) Untreated 0 5 10 15 20 25 Spring Dead Spot Index (diameter*incidence) Dunnett’s Test
  45. 45. Prevention of Spring Dead Spot with Fungicides Banner Maxx (4 fl oz, 2X) * Eagle (2.4 fl oz, 2X) * Headway (3 fl oz, 2X) * Heritage (0.4 oz, 2X) Lynx (2 fl oz, 2X) * Rubigan (6 fl oz, 1X) * Rubigan (4 fl oz, 2X) * Rubigan (6 fl oz, 2X) * Untreated 0 5 10 15 20 25 Spring Dead Spot Index (diameter*incidence) Dunnett’s Test
  46. 46. Prevention of Spring Dead Spot with Fungicides Banner Maxx (4 fl oz, 2X) * Eagle (2.4 fl oz, 2X) * * Headway (3 fl oz, 2X) * * Heritage (0.4 oz, 2X) Lynx (2 fl oz, 2X) * * Rubigan (6 fl oz, 1X) * * Rubigan (4 fl oz, 2X) * * Rubigan (6 fl oz, 2X) * * Untreated 0 5 10 15 20 25 Spring Dead Spot Index (diameter*incidence) Dunnett’s Test
  47. 47. Conclusions: Fertilization Programs and PreventiveFungicides for SDS Management
  48. 48. Conclusions: Fertilization Programs and PreventiveFungicides for SDS Management• Spring dead spot pathogens exhibited a differential response to nitrogen sources
  49. 49. Conclusions: Fertilization Programs and PreventiveFungicides for SDS Management• Spring dead spot pathogens exhibited a differential response to nitrogen sources • O. korrae was effectively suppressed by calcium nitrate
  50. 50. Conclusions: Fertilization Programs and PreventiveFungicides for SDS Management• Spring dead spot pathogens exhibited a differential response to nitrogen sources • O. korrae was effectively suppressed by calcium nitrate • O. herpotricha was suppressed most effectively by ammonium sulfate
  51. 51. Conclusions: Fertilization Programs and PreventiveFungicides for SDS Management• Spring dead spot pathogens exhibited a differential response to nitrogen sources • O. korrae was effectively suppressed by calcium nitrate • O. herpotricha was suppressed most effectively by ammonium sulfate• O. korrae was negatively correlated with soil pH and foliar Ca content, whereas O. herpotricha was positively correlated with these factors
  52. 52. Conclusions: Fertilization Programs and PreventiveFungicides for SDS Management• Spring dead spot pathogens exhibited a differential response to nitrogen sources • O. korrae was effectively suppressed by calcium nitrate • O. herpotricha was suppressed most effectively by ammonium sulfate• O. korrae was negatively correlated with soil pH and foliar Ca content, whereas O. herpotricha was positively correlated with these factors• Fall applications of potassium, dolomitic lime, gypsum, and elemental sulfur had no effect on either spring dead spot pathogen
  53. 53. Conclusions: Fertilization Programs and PreventiveFungicides for SDS Management• Spring dead spot pathogens exhibited a differential response to nitrogen sources • O. korrae was effectively suppressed by calcium nitrate • O. herpotricha was suppressed most effectively by ammonium sulfate• O. korrae was negatively correlated with soil pH and foliar Ca content, whereas O. herpotricha was positively correlated with these factors• Fall applications of potassium, dolomitic lime, gypsum, and elemental sulfur had no effect on either spring dead spot pathogen• Spring dead spot pathogens responded similarly to preventive fungicide applications
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