Progress 01/01/04 to 12/31/09
Outputs
OUTPUTS: Investigations in turfgrass diseases, their cause, nature, and control resulted in numerous print and oral communications, as well as web-based interface providing in-depth descriptions for a better understanding of turfgrass disease characterization and management that was geared toward golf course superintendents, athletic turfgrass managers, lawn care operators, and home owners. Outputs from this CRIS project delivered five peer-reviewed manuscripts; 21 research reports to various granting agencies; 12 newsletters that targeted turfgrass managers; 40 oral presentations delivered at national, professional meetings, regional turfgrass conferences, field days, workshops, and short courses; 17 poster presentations; 16 research abstracts; five popular journal articles (print/web); two Master of Science theses; three research webcasts. The manuscripts and oral presentations had the greatest impact on delivering new information and results from research projects conducted based on the goals and objectives of this CRIS project. The manuscripts were cited by colleagues conducting research in plant pathology. The oral presentations, particularly those presented to clientele in the turfgrass industry were most important. The information disseminated to these groups can be put into practice by the turfgrass managers, the end-users of our scientific research endeavours. PARTICIPANTS: Individuals who participated in this CRIS project include: Maria Tomaso-Peterson (PI); Mr. Hunter Perry, graduate research assistant (GRA) conducted research on spring dead spot of bermudgrass; Mr. Joseph Young (GRA) conducted research on identification of Colletotrichum cereale resistance to azoxystrobin and thiophanate-methyl fungicides; Ms. Tiffany Bennett Crutchfield, undergraduate student worker (USW) assisted in molecular characterization of fungal agents causing turfgrass diseases; Mr. Justin Garnett (USW), Mr. Parker Hite (USW), Mr. Tyler Sandlin (USW), Mr. Joseph Nelson (USW), Mr. Andy Willingham (USW) assisted with field, greenhouse, and laboratory research throughout the duration of this project. Partner organizations involved in support of this research include: NOER Turfgrass Foundation, United States Golf Association, Mississippi Turfgrass Association, Memphis-area Golf Course Superintendents Association (GCSA), Louisiana-Mississippi GCSA, Alabama Turfgrass Foundation, BASF, Syngenta, Cleary Chemical, Bayer, and Gowan Company. Collaborators include: Dr. Frank Wong, Dept. Plant Pathology, University of California-Riverside, Dr. Jo Anne Crouch, Cereal Disease Laboratory, USDA-ARS, St. Paul, MN, and Dr. Young-Ki Jo, Dept. Plant Pathology & Microbiology, Texas A&M University. Professional development associated with this project include: two Master's of Science graduate students, Mr. Hunter Perry and Mr. Joseph Young. Ms. Tiffany Crutchfield conducted undergraduate research and presented results at the Mississippi State University Undergraduate Research Symposium. TARGET AUDIENCES: Information and results garnered from this CRIS project were delivered to professional plant pathologists of national and international audiences. Golf course superintendents, athletic field turfgrass managers, lawn care operators, and home owners were also presented pertitnent information concerning turfgrass diseases; their cause, nature, and control. Efforts were made to disseminate information regarding turfgrass diseases; their cause, nature, and control through a formal turfgrass disease course offered to undergraduate and graduate students at Mississippi State University which includes a laboratory where students get hands-on experience identifying turfgrass diseases and using microscopic and molecular techniques to identify the pathogens. Students also design and execute fungicide trials on putting green turf to observe the efficacy of fungicides for controlling turfgrass diseases. Microscopic identification of turfgrass diseases is also offered at the annual Mississippi State University Turfgrass Short Course and at the annual Golf Industry Show. Research updates are delivered through oral presentation to golf course superintendents at local and regional workshops and chapter meetings. Field research on turfgrass diseases is highlighted at the annual Mississippi State University Turfgrass Field Day where golf course superintendents, industry consultants, lawn care operators, grounds crews from city parks and recreation, high school athletic field managers, and home owners are participating. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
A survey of dematiaceous hyphomycete fungi from infected bermudagrass varieties was investigated. Results indicate Bipolaris spicifera is isolated most frequently from leaves, crowns, and roots of several bermudgrass varieties. Bipolaris sorokiniana, B. cynodontis, and Curvularia lunata, and Exserohilum rostrata are routinely isolated from symptomatic bermudagrass plant parts but at lower frequencies. A three-year biofungicide demonstration trial for controlling dollar spot of bermudagrass was investigated. Biofungicides and conventional fungicides were included. An organic fertilizer was integrated into the trial. The results suggest that biofungicides, applied in conjunction with an organic nitrogen source, can enhance dollar spot control. A three year study on spring dead spot (SDS) management of bermudagrass and seasonal activity of the causal organism, Ophiosphaerella korrae was concluded in 2007. Results indicated the causal agent has the highest root colonization in the winter and spring months. A three-year study on the influence of host resistance and nitrogen levels on leaf spot of bermudagrass was conducted. Two improved cultivars were identified that had improved field tolerance to leaf spot compared to standard cultivars. Nitrogen fertility increased leaf spot severity in cultivars that had poor field tolerance. Isolates of the turfgrass anthracnose causal agent, Colletotrichum cereale were evaluated for fungicide resistance to two common fungicides, azoxystrobin and thiophanate methyl. All C. cereale isolates collected from putting greens in the MS, and AL were resistant to both fungicides. As a result, multiple resistance has been identified. Two novel point mutations were identified in the gene that is targeted by thiophanate-methyl resulting in fungicide resistance. This study was the first to confirm azoxystrobin resistance using molecular characterization of C. cereale. The application of conventional fungicides plays a major role in the management of turfgrass diseases; however, fungicide resistance has been documented in these research efforts. A field study on SDS management was initiated to determine efficacy of seasonal fungicide applications that may reduce SDS incidence and severity. In 2008, spring followed by fall fungicide applications reduced SDS severity. Spring applications did not control SDS. In 2009, spring, spring followed by fall or fall fungicide applications reduced SDS. A new foliar disease of bermudagrass and zoysiagrass golf turf was characterized. Efforts focused on identification of the pathogen, a new species of Exserohilum, based on sequencing of ITS1 and ITS4 regions of mDNA. A new disease in centipedegrass home lawns was characterized. A phylogenetic analysis of the causal agent, C. sublineolum resulted in the identification of a new subspecies. This is a first report of centipedegrass as a host of C. sublineolum. Through investigations of the cause and nature of turfgrass diseases, appropriate management practices and targeted fungicide (biological and/or chemical) applications can be defined based on the life cycles of the pathogens.
Publications
- H. M. T. Bandara Herath, Wimal H. M. W. Herath, Paulo Carvalho, Shabana I. Khan, Babu L. Tekwani, Stephen O. Duke, Maria Tomaso-Peterson, and N. P. Dhammika Nanayakkara. 2009. Biologically Active Tetranorditerpenoids from the Fungus Sclerotinia homoeocarpa, Causal Agent of Dollar Spot in Turfgrass. Journal of Natural Products. 72:2091-2097.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Investigations in turfgrass diseases, their cause, nature, and control resulted in six popular articles, eight abstracts and newsletters, two webinars (web-based seminars), five poster and seven oral presentations at state and national meetings. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
A new study on spring dead spot management was initiated in 2007 to determine whether spring fungicide applications reduce spring dead spot incidence and severity. In the spring of 2008, fungicide applications had a significant effect on spring dead spot. Rubigan treatments applied in April, Sept., Oct., or Sept. and Oct.; Sept. application of Rubigan tank-mixed with thiophanate-methyl; Oct. and Nov. applications of propaconazole and myclobutanil, respectively, were all similar with spring dead spot ratings of > 8.5. Rubigan applied in March, April, May or March, April, Sept., Oct. and the untreated control were similar with an average spring dead spot rating of 7.3. We anticipate the results of this study will identify a fungicide/fertility disease management program efficacious for controlling spring dead spot of bermudagrass managed as fairway turf. The influence of host resistance and nitrogen levels on leaf spot of bermudagrass were evaluated again in 2008. Two improved cultivars were significantly less susceptible to leaf spot pathogens compared to standard cultivars. Nitrogen fertility did not influence leaf spot severity. In these same bermudagrass plots, leaf samples are collected monthly that are symptomatic for leaf spot. The infected tissues are cleaned, plated and the fungal colonization of those bermudagrass tissues is determined. Bipolaris cynodontis is the predominant leaf spot pathogen present April through June. From July through October Curvularia spp. is the most prominent fungus but is considered a secondary invader of infected tissue. Isolates of Colletotrichum cereale were evaluated for fungicide resistance to two common fungicides, azoxystrobin and thiophanate methyl. All C. cereale isolates collected from putting greens in the MS, and AL were resistant to both fungicides. Multiple resistance has also been identified based on results of this study. The resident fungi causing anthracnose are resistant to two separate fungicide chemistries. This resistance factor has only been identified in C. cereale populations in California. A disease of bermudagrass and zoysiagrass golf turf was observed in 2008. Efforts have focused on identification of the pathogen which tentatively is Exserohilum sp. based on sequencing of ITS1 and ITS4 regions of mDNA. Koch's postulates were successfully completed on bermudagrass and zoysiagrass, confirming Exserohilum sp. is the causal organism of the new leaf spot disease. A new pathogen of centipedegrass was identified in 2008. A disease in centipedegrass home lawns was investigated and Koch's postulates confirmed C. sublineolum as the pathogen. This is a first report of centipedegrass as a host of this pathogen.
Publications
- Tredway, L.P., Tomaso-Peterson, M., Perry, H., and Walker, N.R. 2008. Spring dead spot of bermudagrass: A challenge for researchers and turfgrass managers. Plant Health Progress (accepted July 2009).
- Perry, D.H., M. Tomaso-Peterson, and R.E. Baird. 2008. Seasonal Variation in Frequency of Isolation of Ophiosphaerella korrae from Bermudagrass Roots in Mississippi and Pathogenicity of Selected Isolates. Mycopathologia (submitted).
- Perry, D.H., Tomaso-Peterson, M., and Baird, R. 2008. First report of Ophiosphaerella herpotricha causing spring dead spot of bermudagrass in Mississippi. Plant Dis. Note 92:428.
- Young, J.R., M. Tomaso-Peterson, and J.A. Crouch. 2008. First report of Colletotrichum cereale causing anthracnose foliar blight of creeping bentgrass in Mississippi and Alabama. Plant Dis. Note 92:1475.
- Tomaso-Peterson, M., W. Wells, D. Held, B. Layton, G. Munshaw, and A. Henn. 2008. A Guide for Southern Turfgrass Pests and Their Management. Mississippi State University Printing Service, (in press).
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Investigations in turfgrass diseases, their cause, nature, and control resulted in three popular articles detailing results of spring dead spot research that was geared toward golf course superintendents. Two spring dead spot research reports were submitted to United States Golf Association and the O.J. Noer Turfgrass Research Foundation. One final research report detailing biological control of cogongrass was submitted to the Mississippi Department of Environmental Quality. Six abstracts were prepared as a result of presentations at the American Phytopathological Society and Crop Science Society of America. A newsletter article was submitted to Mississippi Turfgrass Association updating current findings in spring dead spot research. A thesis entitled, Disease Management Strategies for Controlling Spring Dead Spot and Frequency of Occurrence of the Causal Organism Ophiospaerella korrae on Tifway bermudagrass (Cynodon dactylon x C. transvaalensis) was submitted to Mississippi
State University Library. Five poster and eleven oral presentations were given by myself and my graduate students at the American Phytopathological Society annual meeting, Crop Science Society of America international meeting, United States Golf Association site visit, Southern Extension and Research Association Information Exchange Group, and Mississippi and Alabama turfgrass association conferences where all the information disseminated focused on research results pertaining to various aspects of turfgrass disease management.
PARTICIPANTS: Mr. Hunter Perry, Graduate Research Assistant. Graduated in December 2007. Worked on spring dead spot of bermudagrass Mr. Joey Young, Graduate Research Assistant. He is researching fungal resistance to two fungicides currently labeled for disease control in turfgrass. Regional golf course superintendents associations support turfgrass disease research via in-kind support.
TARGET AUDIENCES: Target audiences include all turfgrass managers. Information is presented in workshops and short courses as well as conference meetings.
Impacts
Technology transfer of dollar spot management is the result of successfully demonstrating the efficacy of biofungicides for controlling the most wide spread disease of turfgrass, dollar spot. University cooperators at land grant universities in the southeast are conducting similar demonstration trials utilizing information generated from the previous three year study conducted at Mississippi State University. Based on their respective results, the new biofungicide dollar spot management program will be disseminated to the respective state's turfgrass managers. The objective is to encourage turfgrass managers to incorporate biofungicides into their disease management programs thus reducing reliance on conventional fungicides. A three year study on spring dead spot management of bermudagrass and seasonal activity of the causal organism, Ophiosphaerella korrae was concluded in 2007. Ophiosphaerella korrae is most active in the spring, March through April therefore a
disease management project funded by United States Golf Association was initiated in 2007 to determine whether spring fungicide applications reduce spring dead spot incidence and severity. The influence of host resistance and nitrogen levels on leaf spot of bermudagrass were evaluated in 2007. Two improved cultivars were significantly less susceptible to leaf spot pathogens compared to standard cultivars. Nitrogen fertility did not predispose bermudagrass to increased leaf spot incidence or severity. Results indicate if the host is susceptible, disease incidence is similar regardless of nitrogen levels. Isolates of Colletotrichum cereale were evaluated for fungicide resistance to two popular turfgrass fungicides, azoxystrobin and thiophanate methyl. All C. cereale isolates collected from putting greens in the Mississippi, Tennessee and Alabama region were resistant to discriminatory dose levels of both fungicides. The mechanism of resistance for thiophante methyl has been demonstrated
by identifying two novel amino acid substitutions in the beta tubulin gene where thiophanate methyl targets the fungus. Investigations into turfgrass diseases, their cause, nature and control are necessary for maintaining healthy turfgrass. The application of conventional fungicides plays a major role in the management of turfgrass diseases. Complications due to fungicide runoff into ponds, lakes, streams and other aquatic habitats are possible. Fungicides may also be destructive to beneficial and non-targeted microbes and induce fungicide resistance which has now been documented in these research efforts. The application of fungicides in the appropriate manner is important however the question of environmental stewardship must be recognized. Biofungicides in addition to organic fertilizers can be an alternative to synthetic fungicides, in turn reducing the level of chemical input into the environment for disease control. Through investigations of the cause and nature of turfgrass
diseases, appropriate management practices and targeted fungicide (biological and/or chemical) applications can be defined based on the life cycles of the pathogens.
Publications
- Tomaso-Peterson, M., and Trevathan, L.E. 2007. Characterization of Rhizoctonia-like fungi isolated from agronomic crops and turfgrasses in Mississippi. Plant Dis. 91:260-265.
- Tomaso-Peterson, M., and Perry, D. H. 2007. The role of biofungicides and organic fertilizer in the management of dollar spot in bermudagrass. Online. Applied Turfgrass Science doi:10.1094/ATS-2007-0911-01-RS.
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Progress 01/01/06 to 12/31/06
Outputs
Dollar spot is a ubiquitous disease affecting all turfgrass. The causal organism, Sclerotinia homoeocarpa, infects foliar tissue resulting in circular, straw-colored blighted patches 2-3 inches in diameter on closely mowed turfgrass. Conventional fungicides are routinely applied in preventive spray programs. A biofungicide demonstration trial for controlling dollar spot of bermudagrass was repeated for a third year. Biofungicides included were EcoGuard, TurfShield, ZeroTol and Actinovate SP along with conventional fungicides. An organic nitrogen source was applied to integrate holistic control of dollar spot using natural products. The objectives were 1) demonstrate the efficacy of biofungicides for controlling dollar spot on bermudagrass, 2) demonstrate the efficacy of biofungicides in rotation or tank-mixed with conventional, and 3) demonstrate the benefit of integrating a natural, slow-release organic fertilizer into a biofungicide program designed to control
dollar spot of bermudagrass. The results of the 2006 demonstration trial indicate that biofungicides may be used alone or in rotation with conventional fungicides in a preventive or curative manner for acceptable control of dollar spot in bermudagrass. The addition of nitrogen in an organic form enhanced the efficacy of some biofungicides that without the nitrogen source provided marginal control. These results suggest that biofungicides, applied in conjunction with an organic nitrogen source, can enhance dollar spot control. A three-year study investigating spring dead spot of hybrid bermudagrass is ongoing. Results to date indicate the causal organism of spring dead spot, Ophiosphaerella korrae, infects bermudagrass roots early in the growing season, contrary to reports in the literature. Seven treatments, replicated four times in a randomized complete block design, are included in this study. Components of an integrated disease management program were designated as treatments.
Improved seeded bermudagrass varieties are readily making their way as a viable option for turf establishment. Bermudagrasses are inherently susceptible to infection by dematiaceous fungal pathogens that cause leaf spot/melting out disease complex. Seeded bermudagrass varieties were screened for resistance to B. spicifera in the greenhouse. Preliminary results indicate some varieties are more resistant to leaf spot caused by B. spicifera. Field plots of seeded bermudagrass varieties were established in the summer of 2005. Host resistance to leaf spot and the influence of nitrogen fertility on disease severity was monitored in 2006. Results from seeded bermudagrass leaves, crowns, and roots symptomatic for leaf spot indicate Bipolaris spicifera was the most frequently isolated dematiaceous fungal pathogen. Bipolaris sorokiniana, B. cynodontis, Curvularia lunata, and Exserohilum rostratum were also isolated from the same plant parts, but at lower frequencies.
Impacts
Investigations into turfgrass diseases, their cause, nature and control are necessary for maintaining healthy turfgrass. The application of conventional fungicides plays a major role in the management of turfgrass diseases. Complications due to fungicide runoff into ponds, lakes, streams and other aquatic habitats are possible. Fungicides may also be destructive to beneficial and non-targeted microbes and induce fungicide resistance. The application of fungicides in the appropriate manner is important however the question of environmental stewardship must be recognized. Biofungicides in addition to organic fertilizers can be an alternative to synthetic fungicides, in turn reducing the level of chemical input into the environment for disease control. Through investigations of the cause and nature of turfgrass diseases, appropriate management practices and targeted fungicide (biological and/or chemical) applications can be defined based on the life cycles of the
pathogens. The primary objective of turfgrass diseases: their cause, nature and control is to reduce the severity and occurrence of turfgrass diseases. A reduction in turfgrass diseases through biological, cultural and chemical control translates into efficient economic and environmental turfgrass management practices.
Publications
- Tomaso-Peterson, M., Perry, H., and Meister, C.W. 2006. Control of leaf spot in bermudagrass using Endorse fungicide, 2005. Fungicide and Nematicide Tests. Vol. 61:T026.
- Tomaso-Peterson, M. 2006. A demonstration trial of biofungicides with efficacy for controlling dollar spot in turfgrasses. MAFES Research Report. Vol. 23 No. 17.
- Tomaso-Peterson, M. and D.H. Perry. 2006. The distribution of dematiaceous leaf spot pathogens colonizing naturally-infected bermudagrass tissues. Phytopathology Abstr. 96:S115.
- Perry, H. and M. Tomaso-Peterson. 2006. Frequency of occurrence of Ophiosphaerella korrae on Tifway bermudagrass roots in Mississippi. Phytopathology Abstr. 96:S92.
- Perry, D. H, M. Tomaso-Peterson, and G.C. Munshaw. 2006. Frequency of occurrence of Ophiosphaerella korrae on Tifway bermudagrass roots in Mississippi. Agron. Abstr. 98: cd rom.
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Progress 01/01/05 to 12/31/05
Outputs
Dollar spot is a ubiquitous disease affecting all turfgrass. The causal organism, Sclerotinia homoeocarpa, infects foliar tissue resulting in circular, straw-colored blighted patches 2-3 inches in diameter on closely mowed turfgrass. Conventional fungicides are routinely applied in preventive spray programs. A biofungicide demonstration trial for controlling dollar spot of bermudagrass was repeated for a second year. Biofungicides used in the trial included EcoGuard, TurfShield, ZeroTol and Actinovate SP along with conventional fungicides. The objectives were to demonstrate the efficacy of biofungicides for controlling dollar spot of bermudagrass and to demonstrate the efficacy of biofungicides alternated with conventional fungicides to reduce chemical input while maintaining acceptable disease management of dollar spot in a bermudagrass putting green. The results of the 2005 demonstration trial indicate that biofungicides may be used alone or in rotation with
conventional fungicides in a preventive or curative manner for acceptable control of dollar spot in bermudagrass. In 2005, a trial for evaluating Endorse fungicide for control of leaf spot of bermudagrass was conducted. Endorse fungicide significantly reduced leaf spot severity of bermudagrass. These results will provide the necessary documentation for expanding the Endorse label to include leaf spot control of warm season turfgrass species. A three-year study investigating spring dead spot of hybrid bermudagrass is ongoing. Results to date indicate the causal organism of spring dead spot, Ophiosphaerella korrae, infects bermudagrass roots early in the growing season, contrary to reports in the literature. Seven treatments, replicated four times in a randomized complete block design, are included in this study. Components of an integrated disease management program were designated as treatments. Improved seeded bermudagrass varieties are viewed as a viable option for turf
establishment. Bermudagrasses are inherently susceptible to infection by dematiaceous fungal pathogens that cause leaf spot/melting out disease complex. Seeded bermudagrass varieties were screened for resistance to B. spicifera in the greenhouse. Preliminary results indicate some varieties are resistant to leaf spot caused by B. spicifera. Field plots of seeded bermudagrass varieties were established in the summer of 2005. Host resistance to leaf spot and the influence of nitrogen fertility on disease severity will be determined. Results from bermudagrass leaves, crowns, and roots symptomatic for leaf spot indicate Bipolaris spicifera was the most frequently isolated dematiaceous fungal pathogen. Bipolaris sorokiniana, B. cynodontis, and Curvularia lunata, and Exserohilum rostratum were also isolated from the same plant parts, but at lower frequencies.
Impacts
Investigations into turfgrass diseases, their cause, nature and control are necessary for maintaining healthy turfgrass. The application of conventional fungicides plays a major role in the management of turfgrass diseases. Complications due to fungicide runoff into ponds, lakes, streams and other aquatic habitats are possible. Fungicides may also be destructive to beneficial and non-targeted microbes and induce fungicide resistance. The application of fungicides in the appropriate manner is important however the question of environmental stewardship must be recognized. Biological fungicide use for disease control can be an alternative for chemical applications, in turn reducing the level of chemical input into the environment. Through investigations of the cause and nature of turfgrass diseases, appropriate management practices and targeted fungicide (biological and/or chemical) applications can be defined based on the life cycles of the pathogens. The primary
objective of turfgrass diseases: their cause, nature and control is to reduce the severity and occurrence of turfgrass diseases. A reduction in turfgrass diseases through biological, cultural and chemical control translates into efficient economic and environmental turfgrass management practices.
Publications
- Tomaso-Peterson, M. 2005. Biological and chemical control of dollar spot in bermudagrass, 2004. Fungicide and Nematicide Tests. Vol. 60:T059.
- Tomaso-Peterson, M. and K. Page. 2005. Determination of an etiological agent of cogongrass. Phytopathology. Vol. 69 No. 6:S103. (Abstract)
- Tomaso-Peterson, M. 2005. 2004 IR-4/EPA Demonstration Grant Research Results: Dollar spot/Bermudagrass. The IR-4/EPA Demonstration Grant Report, 2004. http://www.ir4.rutgers.edu/Binars/executivesummary05.pdf
- Tomaso-Peterson, M. 2005. Turfgrass diseaes of the month. Mississippi Turfgrass Association Newsletter. Vol. 36, Jan. 2005. pg.1.
- Tomaso-Peterson, M. 2005. The importance of host resistance in a disease management system. Field Day 23 Guide. Turf Seed, Inc. pgs. 11-12.
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Progress 01/01/04 to 12/30/04
Outputs
Dollar spot is a ubiquitous disease affecting virtually all turfgrass species grown in all turf situations (from home lawns to putting greens). The causal organism, Sclerotinia homoeocarpa, infects foliar tissue resulting in circular, straw-colored blighted patches 2-3 inches in diameter on closely mowed turfgrass. Conventional fungicides are routinely applied in preventive spray programs. The biofungicides included in the demonstration trial were EcoGuard, TurfShield, and ZeroTol. The objectives of the bio-fungicide demonstration trial were 1). Demonstrate the efficacy of EcoGuard, TurfShield, and ZeroTol bio-fungicides for controlling dollar spot in a TifGreen bermudagrass putting green and 2). Demonstrate the efficacy of EcoGuard, TurfShield, and ZeroTol bio-fungicides alternated with conventional fungicides to reduce chemical input and fungal resistance while maintaining acceptable disease management of dollar spot in a TifGreen bermudagrass putting green. Results
indicated that EcoGuard, TurfShield, and ZeroTol were as effective for controlling dollar spot as the standard, conventional fungicides. These bio-fungicides may be used alone or in rotation with conventional fungicides in a preventive or curative manner for controlling dollar spot of bermudagrass. In July of 2004, a three-year study was initiated in a hybrid bermudagrass fairway that is annually symptomatic for spring dead spot. Spring dead spot occurs in intensely managed bermudagrass and is caused by Ophiosphaerella korrae. The pathogen infects the root system of bermudagrass in the latter stages of its growth cycle, depleting the plant of viable roots that are required for initiating new growth in the spring. Seven treatments were replicated four times in a randomized complete block design. Components of an integrated disease management program were designated as treatments. These studies are still in progress. Improved seeded bermudagrass varieties are readily making their way
into golf course fairways, roughs, and tee boxes as well as athletic sports fields and lawns. Bermudagrasses are inherently susceptible to infection by dematiaceous hyphomycete fungi that are involved in the leaf spot/melting out disease complex. A survey of these fungi from infected bermudagrass varieties is being conducted. Preliminary results indicate Bipolaris spicifera is isolated most frequently from leaves, crowns, and roots of several bermudgrass varieties. Bipolaris sorokiniana, B. cynodontis, Curvularia lunata, and Exserohilum rostratum are routinely isolated from symptomatic bermudagrass plant parts.
Impacts
Investigations into turfgrass diseases, their cause, nature and control are necessary for maintaining aesthetically pleasing turfgrasses. The management of turfgrass diseases relies on the use of frequent conventional fungicide applications. Some fungicides are expensive and costly to apply. The extensive use of fungicides can result in runoff into ponds, lakes, streams and other aquatic habitats. Fungicides may also be destructive to beneficial and non-targeted microbes and induce fungicide resistance within isolates of turfgrass pathogens. The application of fungicides in the appropriate manner is important however the question of environmental stewardship must be recognized. Biological fungicide use for disease control can be an alternative for chemical applications, in turn reducing the level of chemical input into the environment. Through investigations of the cause and nature of turfgrass diseases, appropriate management practices and targeted fungicide
(biological and/or chemical) applications can be defined based on the life cycles of the pathogens causing diseases. The primary objective of this research project is to reduce the severity and occurrence of turfgrass diseases. A reduction in turfgrass diseases translates into efficient economic and environmental turfgrass management practices.
Publications
- Tomaso-Peterson, M. and L. E. Trevathan. 2004. Rhizoctonia solani AG-13 Isolated from Corn in Mississippi. Plant Dis. 88:908.
- Tomaso-Peterson, M. 2004. Bio-fungicides show success controlling dollar spot on golf courses. Pesticide Environmental Stewardship Program Update. Vol. 6, No. 2.
- Tomaso-Peterson, M. 2004. Fungicide Update. Mississippi Turfgrass Association Newsletter. Vol. 35, Jul. pg.6.
- Tomaso-Peterson, M. 2004. A demonstration trial of bio-fungicides with efficacy for controlling dollar spot in bermudgrasses. Mississippi Turfgrass Association Newsletter. Vol. 35, Nov. pg.2.
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