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| Web URL(s): | https://repository.lib.ncsu.edu/bitstream/handle/1840.20/38742/etd.pdf?sequence=1&isAllowed=y
Last checked: 04/30/2021
Notes: Item description page |
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| Publication Type:
| Report |
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| Material Type: | Dissertation |
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| Monographic Author(s): | Stephens, Cameron Matthew |
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| Author Affiliation: | North Carolina State University |
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| Monograph Title: | Etiology, Epidemiology, and Management of Take-all Root Rot on Golf Course Putting Greens, 2021. |
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| Publishing Information: | Ph.D Dissertation: North Carolina State University |
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| # of Pages: | 146 |
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| Collation: | xiv, 132 pp. |
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| Keywords: | TIC Keywords: Take-all root rot; Dwarf bermudagrasses; Ectotrophic root-infecting fungi; Gaeumannomyces graminis var. graminis; Golf greens; Application timing; Fungicide selection; Manganese; Cultural methods; Pyraclostrobin; Penthiopyrad; Triadimefon; Propiconazole; Azoxystrobin; Leaching; Bioavailability; Binding afinity; Disease control; Cynodon dactylon x C. transvaalensis; Agrostis stolonifera
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| Cultivar Names: | Champion; Penn A-1 |
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| Abstract/Contents: | "Take-all root rot (TARR) is a detrimental disease of ultradwarf bermudagrass that is caused by multiple soilborne ectotrophic root-infecting fungi including Gaeumannomyces graminis (Gg), Gaeumannomyces sp. (Gx), Gaeumannomyces graminicola (Ggram), Candidacolonium cynodontis (Cc), and Magnaporthiopsis cynodontis (Mc). Many etiological and epidemiological components of TARR remain unknown which has made chemical management of this disease challenging. Therefore, the objectives of this research were to i) determine the influence of postapplication management practices on fungicide movement on a golf course putting green, ii) identify and characterize the aggressiveness of TARR pathogens isolated from symptomatic bermudagrass putting greens iii) determine the in vitro fungicide sensitivity of TARR pathogens and evaluate the influence of organic matter on fungicide bioavailability, and iv) characterize the influence of fungicide selection, fungicide application timing, and manganese applications on TARR management using field trials and in vivo methods. Field studies were initiated to determine the influence of post-application mowing and irrigation timing on pyraclostrobin, penthiopyrad, and triadimefon movement on a golf course putting green. A small amount of fungicide (<3.6%) was removed with clippings regardless of mowing and irrigation treatment. Post-application irrigation timing influenced fungicide movement through the soil profile. Yet, >50% of fungicide remained within the RAV for the first three DATs. In general, less fungicide remained in the RAV and more fungicide was detected in deeper soil depths when plots were irrigated immediately after fungicide application. Isolates of Gg, Gx, Ggram, Cc, and Mc were used to inoculate Champion bermudagrass in an in vivo aggressiveness assay. The growth of each pathogen was also evaluated at 10, 15, 20, 25, 30, and 35°C. Infected plant tissue was used to develop a real-time PCR high resolution melt assay for pathogen detection and quantification. This assay was able to differentiate and quantify each pathogen directly from infected plant tissue using a single primer pair. In general, Ggram, Gg, and Gx were the most aggressive and Cc and Mc exhibited moderate aggressiveness. Pathogens were more aggressive when inoculated at 30°C compared to 20°C. These pathogens grew optimally between 24.4 and 27.8°C, exhibited limited growth at 35°C, and no growth at 10°C. Therefore, chemical management practices should begin when soil temperatures reach 30°C and continue until soil temperatures drop below 15°C. The in vitro sensitivity of Gg, Ggram, Cc, and Mc to 14 different fungicides across three chemical classes was determined. An in vitro bioavailability assay was developed using three fungicides and three organic matter concentrations. DMI and QoI fungicides suppressed mycelial growth the most whereas SDHIs did not reduce mycelial growth. These data can serve a baseline for TARR pathogen sensitivity for future in vitro fungicide sensitivity studies and field efficacy trials. Fungicides from the QoI and/or DMI chemical class also reduced TARR severity under field and greenhouse conditions. Fungicide applications that started in late-July to early-August when soil temperatures were between 25-30°C provided the greatest disease suppression. Bioavailability can be influenced by organic matter concentration and physicochemical properties of fungicides may provide insight into their binding affinity. Fungicides like pyraclostrobin and propiconazole have a high affinity to bind to organic matter which was evident as more fungicide was required to inhibit Gg growth as organic matter concentration increased. This was not observed when evaluating azoxystrobin, which has a lower binding affinity. This research enhances our understanding of fungicide fate on putting greens and improves our knowledge of TARR pathogens and disease management. These data demonstrate fungicide selection, post-application management practice, and proper fungicide application timing are critical for optimizing TARR suppression." |
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| Language: | English |
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| References: | 112 |
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| See Also: | See also related item "Influence of fungicide selection and application timing on take-all root rot management under field and greenhouse conditions" Crop, Forage and Turfgrass Management, 10(1) June 2024, R=334979 R=334979 |
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| Note: | "A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy"
"Plant Pathology"
Advisor: James P. Kerns and Travis W. Gannon
Includes "Dedication"; p. ii
Includes "Biography"; p. iii
Includes "Acknowledgements"; pp. iv-v
Includes "List of tables"; pp. viii
Includes "List of figures"; pp. ix-xiv
Pictures, color
Tables
Graphs |
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| ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Stephens, Cameron Matthew 2021. Etiology, Epidemiology, and Management of Take-all Root Rot on Golf Course Putting Greens. Ph.D Dissertation: North Carolina State University. |
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| Web URL(s):
https://repository.lib.ncsu.edu/bitstream/handle/1840.20/38742/etd.pdf?sequence=1&isAllowed=y
Last checked: 04/30/2021
Notes: Item description page |
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