NE1046: Management of Annual Bluegrass on Golf Courses: Improved Practices for Maintenance, Pest Control, and Viable Techniques for Transition to Mo
(Multistate Research Project)
Status: Inactive/Terminating
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Rationale and importance of work: Turfgrass areas including golf courses are a valuable and rapidly expanding component of urban and rural landscapes covering 12 million ha in the United States (Potter & Braman 1991). Over 16,000 golf courses in the U.S. provide green space in the urban environment; offer recreation for 36 million Americans; generate jobs, commerce, economic development, and tax revenues for communities; and contribute $62.2 billion worth of goods/services each year to the national economy (www.golf2020.com).
Annual bluegrass (Poa annua) is a highly invasive weed on short-mown golf course surfaces (fairways, tees, putting greens) where it often becomes the dominant species despite extensive attempts to suppress it. Superintendents often resort to managing it instead of more pest-tolerant bentgrasses (Agrostis spp.) (Miltner et al. 2004). P. annua can provide an acceptable playing surface for putting greens and fairways when properly maintained, but this requires extensive chemical inputs (Grant & Rossi 2005). It has high tiller density and tolerance of low cutting heights, shade and traffic, but is often maligned for its lack of stress tolerance, yellow-green color, prolific flowering habit, and susceptibility to many diseases and insect pests (Beard 1973).
Improved agronomic management practices are widening the possibilities for maintaining P annua in the turfscape. But some of these practices may enhance pest problems (Inguagiato et al. 2008). P. annua maintenance on golf courses in the Northeast and Mid-Atlantic has become increasingly complicated by two emergent pests. The annual bluegrass weevil (ABW) (Listronotus maculicollis) and anthracnose diseases (anthracnose basal rot = ABR) caused by the fungus Colletotrichum cereale have become in recent years the most severe pests of P. annua. Their control often depends almost entirely on chemical pesticides with multiple applications required throughout the growing season. However, the general public is increasingly concerned about the potential for pesticide exposure and long-term effects to humans and pets and the possibility of ground and surface water contamination. Extensive pesticides use to control these pests also reduces golf course profitability. In addition, insecticide resistant ABW populations and fungicide resistant C. cereale isolates are an increasing problem. There is an urgent need to refine our understanding of the biology, ecology, and pathogenesis of these pests, develop better IPM tools to assess and monitor their impact, discover and deploy more effective pest management practices, and gain a better understanding of the stresses that affect P. annua and how to mitigate them. To address this need, a regional project was initiated in 2005 (NE1025: Biology, Ecology, and Management of Emerging Pests of Annual Bluegrass on Golf Courses).
The ABW is a notorious and damaging pest of close-cut P. annua on golf courses and tennis courts in the northeastern U.S. ABW injury to turfgrass was first reported in CT in 1931 (Britton 1932) and until the last 20 years has been concentrated in the NY metropolitan area. Severe infestations are now reported from all other states of the Northeast and Mid-Atlantic, west into OH and Ontario and north into Quebec. Although not always present in turfgrass settings, the ABW has been reported from > 40 states, suggesting the potential exists for spread of impact across much of the U.S. and Canada.
In spring adult ABW move from off-course overwintering sites to the greens, tees, and fairways. As the insect completes 2-3 generations, the heavy damage inflicted by the stem-boring and crown-feeding larvae severely impacts the visual and functional quality of the turf. The problem is exacerbated because P. annua is least vigorous during the summer, which coincides with the peak of ABW feeding activity. In the proposal for NE1025 (in 2005), we stated that pyrethroid insecticides targeting adults were the only effective control option with superintendents making 2-5 applications per season putting ABW populations under strong selective pressure for developing resistance to this chemical class. Indeed, resistance has been confirmed (Ramoutar et al. 2009a) and seems to be on the rise. While the concerted efforts of NE1025 members has defined effective alternatives to pyrethroids (e.g., trichlorfon, spinosad, indoxacarb, chlorantraniliprole), ABW populations already resistant to pyrethroids seem to also be less susceptible to these alternatives (R.S. Cowles, pers. observation). Almost no presently available insecticides effectively control the most resistant ABW populations.
Anthracnose is the common name given to leaf diseases that occur throughout the world on almost all turfgrass species. They are particularly severe on P. annua and to a lesser extent on creeping bentgrass (Agrostis stolonifera). The anthracnose pathogen that attacks turfgrass had previously been identified as C. graminicola, a well-known pathogen of maize, but recent studies confirmed that pooid-infecting isolates differ substantially from the maize pathogen, prompting the resurrection of the original name, C. cereale (see below). C. cereale may cause a foliar blight or basal rot of leaf and sheath tissue (Smiley et al. 2005). In recent years incidence and severity of ABR on golf courses have increased throughout the U.S. (Dernoeden 2000, Landschoot & Hoyland 1995, Vermeulen 2003, Wong & Midland 2004) and Canada (Hsiang & Goodwin 1999). It has recently been shown that the increased frequency of ABR on putting greens is associated with the intensive management practices (e.g., low cutting heights, reduced nitrogen fertility, low soil water; Inguagiato et al. 2008, 2009b, Roberts et al. 2011) employed by superintendents to meet the ever-increasing expectations of the golfing public.
Superintendents often rely heavily on fungicides for disease suppression. But relying solely on fungicides is costly and has met with variable results, particularly when plants are under stress. Products are most effective when applied preventatively, but due to our incomplete knowledge of pathogen biology and fungicide timing, treatments are often ineffective. Because of the increasing use of fungicides to control ABR and the limited number of efficacious compounds, resistance to the benzimidazole and strobilurin fungicides has recently occurred on many golf courses in the U.S. (Avila-Adame et al. 2003). It is likely that fungicide resistance will become more widespread if current chemical and cultural control practices are not altered.
NE1025 members have have filled many gaps in our understanding of the biology, ecology, and impact of ABW and ABR; identified and tested new control options; developed improved IPM decision tools; and continuously updated best management practices (BMPs) based on the new information generated. But there are still many other aspects in the biology/ecology and management of ABW, ABR, and P. annua itself that require further regional efforts to develop optimal BMPs. Given the dominance of P. annua in many golf course fairways and greens and the absence of proven methods for its suppression, the continued optimization of BMPs for P. annua is a major goal of the proposed project. However, the recent advent of new herbicide chemistries for P. annua control (e.g., bispyribac sodium, amicarbazone, methiozolin) and modified use strategies of existing have enhanced the potential for the development of better methods to prevent its establishment and spread, and to transition to more sustainable turfgrass spp. The development of improved cultural techniques, either alone or in combination with biorationals and herbicides, to reduce/eliminate P. annua in favor of more desirable turfgrass species is a long term goal of the proposed project. Both goals should be pursued and coordinated to improve the overall sustainability of golf courses and to enhance the economic and environmental well being of this industry.
Need for project as indicated by stakeholders: In January 2001, a broad-based group of stakeholders interested in golf course IPM in the Northeast met at Rutgers University (NJ). This focus group included superintendents, university personnel, environmental and public health advocates, and representatives from the US Golf Association and the US EPA. Research and extension priorities cited by this group included (1) alternatives to current chemical pesticides, (2) forecast and sampling protocols for important golf turf pests, and (3) a comprehensive Web-based treatment of golf turf IPM. For a complete summary of the groups priorities see: http://northeastipm.org/ partners/priorities/ turf2001.html. Our proposed project will directly address these priorities as well as other gaps in knowledge and management practices associated with P. annua itself and its major pests, the ABW and anthracnose disease.
Consequences if it is not done: If the proposed research on management of P. annua and its major pests, ABW and ABR, and the suppression of P. annua/transition to more sustainable turfgrasses is not conducted, the consequences will likely be (1) further spread and intensification of pest resistance to several insecticide and fungicide chemistries, (2) increased economic and environmental costs associated with the application of chemical pesticides used to control these pests, (3) reduced likelihood that ABR -resistant grass varieties will be developed and marketed, (4) loss of revenue in the golf course industry due to widespread turf failure, and (5) lack of an integrated management system for intensely managed turf.
Technical feasibility: Most scientists involved with the ABW, ABR, and P annua management sections of this project have been collaboratively studying and publishing on these issues at least since the inception of NE1025 in 2005. New scientists on the project bring additional expertise, further enhancing collaborations and productivity of the team. Breeding programs in the region have extensive collections of P. annua (PA) and creeping bentgrass germplasm (NJ) that will continue to be shared in a coordinated fashion to determine the potential for genetic resistance to ABW and ABR. All scientists involved with the section on P. annua suppression/transition to more sustainable grasses already have experience working with this plant; the involved weed scientists already have studied the suppression of P. annua for several years. Combining their efforts will aid in the development of an effective suppression program. Many of the PIs currently have Cooperative Extension and outreach appointments and have extensive experience and successful track records in impact assessment and dissemination of research results to turfgrass practitioners throughout the U.S.
Advantages of a multistate effort: Turfgrass fungal and insect problems occur across state boundaries, so it is imperative to develop control strategies appropriate for the broadest geographic region possible. A multistate effort will increase the exchange of knowledge, experience, and techniques among scientists who would not otherwise have cooperated on these pest problems. A major practical goal of the multistate project is to coordinate breeding goals and control regimes such that time and money are not wasted. Standardized surveys/ questionnaires conducted at the conclusion of the current and proposed projects will be compared to provide a comprehensive evaluation of project impacts. Division of labor and collaboration according to the primary expertise of the involved labs will improve the quality of specific studies. Outcomes from the various labs will help other labs advance more quickly with their research/outreach efforts. This regional approach will allow us to conduct multisite studies across the Northeast and Mid-Atlantic. Bringing entomologists, pathologists, physiologists, weed scientists, management specialists, and plant breeders together will result in a better understanding of the biology and control/suppression of P. annua and its major pests, and will allow ABR. Finally, a multistate effort will allow scientists to develop a set of best management practices (BMPs) that will help practitioners successfully maintain or suppress, as needed, P. annua while reducing pesticide use. Project participants will relay detailed, relevant findings to practitioners through regional and national seminars, symposia, electronic newsletters, annual research field days, and multi-authored publications in a coordinated fashion.
Anticipated impacts: Our interdependent research strategy will lead to improved exchange of information among turfgrass management specialists, entomologists, weed scientists, breeders, pathologists, and physiologists throughout the U.S. A publication containing BMPs for P. annua, currently being developed by members of NE1025, will be updated/improved based on newly developed information. A publication containing BMPs for suppressing P. annua /transition to more sustainable turfgrass will be developed and disseminated to turfgrass managers in the region via this multistate effort. This and other applied publications developed through this project will be posted on the NIMSS website. The information will lead to improved management practices being adopted by golf course superintendents including the use of new biological, biorational, and chemical strategies, and new cultural and ecologically based control techniques. Adoption and implementation of this information by practitioners will result in improved management of P. annua and its major pests, or the transition of P. annua-dominated areas to more sustainable turfgrasses with reduced pesticide requirements, and ultimately enhanced economic and environmental health benefits across the region. Project impact will be measured with a survey conducted throughout the Northeast region in year 5 of the current project and year 4 of the proposed project.
Annual bluegrass (Poa annua) is a highly invasive weed on short-mown golf course surfaces (fairways, tees, putting greens) where it often becomes the dominant species despite extensive attempts to suppress it. Superintendents often resort to managing it instead of more pest-tolerant bentgrasses (Agrostis spp.) (Miltner et al. 2004). P. annua can provide an acceptable playing surface for putting greens and fairways when properly maintained, but this requires extensive chemical inputs (Grant & Rossi 2005). It has high tiller density and tolerance of low cutting heights, shade and traffic, but is often maligned for its lack of stress tolerance, yellow-green color, prolific flowering habit, and susceptibility to many diseases and insect pests (Beard 1973).
Improved agronomic management practices are widening the possibilities for maintaining P annua in the turfscape. But some of these practices may enhance pest problems (Inguagiato et al. 2008). P. annua maintenance on golf courses in the Northeast and Mid-Atlantic has become increasingly complicated by two emergent pests. The annual bluegrass weevil (ABW) (Listronotus maculicollis) and anthracnose diseases (anthracnose basal rot = ABR) caused by the fungus Colletotrichum cereale have become in recent years the most severe pests of P. annua. Their control often depends almost entirely on chemical pesticides with multiple applications required throughout the growing season. However, the general public is increasingly concerned about the potential for pesticide exposure and long-term effects to humans and pets and the possibility of ground and surface water contamination. Extensive pesticides use to control these pests also reduces golf course profitability. In addition, insecticide resistant ABW populations and fungicide resistant C. cereale isolates are an increasing problem. There is an urgent need to refine our understanding of the biology, ecology, and pathogenesis of these pests, develop better IPM tools to assess and monitor their impact, discover and deploy more effective pest management practices, and gain a better understanding of the stresses that affect P. annua and how to mitigate them. To address this need, a regional project was initiated in 2005 (NE1025: Biology, Ecology, and Management of Emerging Pests of Annual Bluegrass on Golf Courses).
The ABW is a notorious and damaging pest of close-cut P. annua on golf courses and tennis courts in the northeastern U.S. ABW injury to turfgrass was first reported in CT in 1931 (Britton 1932) and until the last 20 years has been concentrated in the NY metropolitan area. Severe infestations are now reported from all other states of the Northeast and Mid-Atlantic, west into OH and Ontario and north into Quebec. Although not always present in turfgrass settings, the ABW has been reported from > 40 states, suggesting the potential exists for spread of impact across much of the U.S. and Canada.
In spring adult ABW move from off-course overwintering sites to the greens, tees, and fairways. As the insect completes 2-3 generations, the heavy damage inflicted by the stem-boring and crown-feeding larvae severely impacts the visual and functional quality of the turf. The problem is exacerbated because P. annua is least vigorous during the summer, which coincides with the peak of ABW feeding activity. In the proposal for NE1025 (in 2005), we stated that pyrethroid insecticides targeting adults were the only effective control option with superintendents making 2-5 applications per season putting ABW populations under strong selective pressure for developing resistance to this chemical class. Indeed, resistance has been confirmed (Ramoutar et al. 2009a) and seems to be on the rise. While the concerted efforts of NE1025 members has defined effective alternatives to pyrethroids (e.g., trichlorfon, spinosad, indoxacarb, chlorantraniliprole), ABW populations already resistant to pyrethroids seem to also be less susceptible to these alternatives (R.S. Cowles, pers. observation). Almost no presently available insecticides effectively control the most resistant ABW populations.
Anthracnose is the common name given to leaf diseases that occur throughout the world on almost all turfgrass species. They are particularly severe on P. annua and to a lesser extent on creeping bentgrass (Agrostis stolonifera). The anthracnose pathogen that attacks turfgrass had previously been identified as C. graminicola, a well-known pathogen of maize, but recent studies confirmed that pooid-infecting isolates differ substantially from the maize pathogen, prompting the resurrection of the original name, C. cereale (see below). C. cereale may cause a foliar blight or basal rot of leaf and sheath tissue (Smiley et al. 2005). In recent years incidence and severity of ABR on golf courses have increased throughout the U.S. (Dernoeden 2000, Landschoot & Hoyland 1995, Vermeulen 2003, Wong & Midland 2004) and Canada (Hsiang & Goodwin 1999). It has recently been shown that the increased frequency of ABR on putting greens is associated with the intensive management practices (e.g., low cutting heights, reduced nitrogen fertility, low soil water; Inguagiato et al. 2008, 2009b, Roberts et al. 2011) employed by superintendents to meet the ever-increasing expectations of the golfing public.
Superintendents often rely heavily on fungicides for disease suppression. But relying solely on fungicides is costly and has met with variable results, particularly when plants are under stress. Products are most effective when applied preventatively, but due to our incomplete knowledge of pathogen biology and fungicide timing, treatments are often ineffective. Because of the increasing use of fungicides to control ABR and the limited number of efficacious compounds, resistance to the benzimidazole and strobilurin fungicides has recently occurred on many golf courses in the U.S. (Avila-Adame et al. 2003). It is likely that fungicide resistance will become more widespread if current chemical and cultural control practices are not altered.
NE1025 members have have filled many gaps in our understanding of the biology, ecology, and impact of ABW and ABR; identified and tested new control options; developed improved IPM decision tools; and continuously updated best management practices (BMPs) based on the new information generated. But there are still many other aspects in the biology/ecology and management of ABW, ABR, and P. annua itself that require further regional efforts to develop optimal BMPs. Given the dominance of P. annua in many golf course fairways and greens and the absence of proven methods for its suppression, the continued optimization of BMPs for P. annua is a major goal of the proposed project. However, the recent advent of new herbicide chemistries for P. annua control (e.g., bispyribac sodium, amicarbazone, methiozolin) and modified use strategies of existing have enhanced the potential for the development of better methods to prevent its establishment and spread, and to transition to more sustainable turfgrass spp. The development of improved cultural techniques, either alone or in combination with biorationals and herbicides, to reduce/eliminate P. annua in favor of more desirable turfgrass species is a long term goal of the proposed project. Both goals should be pursued and coordinated to improve the overall sustainability of golf courses and to enhance the economic and environmental well being of this industry.
Need for project as indicated by stakeholders: In January 2001, a broad-based group of stakeholders interested in golf course IPM in the Northeast met at Rutgers University (NJ). This focus group included superintendents, university personnel, environmental and public health advocates, and representatives from the US Golf Association and the US EPA. Research and extension priorities cited by this group included (1) alternatives to current chemical pesticides, (2) forecast and sampling protocols for important golf turf pests, and (3) a comprehensive Web-based treatment of golf turf IPM. For a complete summary of the groups priorities see: http://northeastipm.org/ partners/priorities/ turf2001.html. Our proposed project will directly address these priorities as well as other gaps in knowledge and management practices associated with P. annua itself and its major pests, the ABW and anthracnose disease.
Consequences if it is not done: If the proposed research on management of P. annua and its major pests, ABW and ABR, and the suppression of P. annua/transition to more sustainable turfgrasses is not conducted, the consequences will likely be (1) further spread and intensification of pest resistance to several insecticide and fungicide chemistries, (2) increased economic and environmental costs associated with the application of chemical pesticides used to control these pests, (3) reduced likelihood that ABR -resistant grass varieties will be developed and marketed, (4) loss of revenue in the golf course industry due to widespread turf failure, and (5) lack of an integrated management system for intensely managed turf.
Technical feasibility: Most scientists involved with the ABW, ABR, and P annua management sections of this project have been collaboratively studying and publishing on these issues at least since the inception of NE1025 in 2005. New scientists on the project bring additional expertise, further enhancing collaborations and productivity of the team. Breeding programs in the region have extensive collections of P. annua (PA) and creeping bentgrass germplasm (NJ) that will continue to be shared in a coordinated fashion to determine the potential for genetic resistance to ABW and ABR. All scientists involved with the section on P. annua suppression/transition to more sustainable grasses already have experience working with this plant; the involved weed scientists already have studied the suppression of P. annua for several years. Combining their efforts will aid in the development of an effective suppression program. Many of the PIs currently have Cooperative Extension and outreach appointments and have extensive experience and successful track records in impact assessment and dissemination of research results to turfgrass practitioners throughout the U.S.
Advantages of a multistate effort: Turfgrass fungal and insect problems occur across state boundaries, so it is imperative to develop control strategies appropriate for the broadest geographic region possible. A multistate effort will increase the exchange of knowledge, experience, and techniques among scientists who would not otherwise have cooperated on these pest problems. A major practical goal of the multistate project is to coordinate breeding goals and control regimes such that time and money are not wasted. Standardized surveys/ questionnaires conducted at the conclusion of the current and proposed projects will be compared to provide a comprehensive evaluation of project impacts. Division of labor and collaboration according to the primary expertise of the involved labs will improve the quality of specific studies. Outcomes from the various labs will help other labs advance more quickly with their research/outreach efforts. This regional approach will allow us to conduct multisite studies across the Northeast and Mid-Atlantic. Bringing entomologists, pathologists, physiologists, weed scientists, management specialists, and plant breeders together will result in a better understanding of the biology and control/suppression of P. annua and its major pests, and will allow ABR. Finally, a multistate effort will allow scientists to develop a set of best management practices (BMPs) that will help practitioners successfully maintain or suppress, as needed, P. annua while reducing pesticide use. Project participants will relay detailed, relevant findings to practitioners through regional and national seminars, symposia, electronic newsletters, annual research field days, and multi-authored publications in a coordinated fashion.
Anticipated impacts: Our interdependent research strategy will lead to improved exchange of information among turfgrass management specialists, entomologists, weed scientists, breeders, pathologists, and physiologists throughout the U.S. A publication containing BMPs for P. annua, currently being developed by members of NE1025, will be updated/improved based on newly developed information. A publication containing BMPs for suppressing P. annua /transition to more sustainable turfgrass will be developed and disseminated to turfgrass managers in the region via this multistate effort. This and other applied publications developed through this project will be posted on the NIMSS website. The information will lead to improved management practices being adopted by golf course superintendents including the use of new biological, biorational, and chemical strategies, and new cultural and ecologically based control techniques. Adoption and implementation of this information by practitioners will result in improved management of P. annua and its major pests, or the transition of P. annua-dominated areas to more sustainable turfgrasses with reduced pesticide requirements, and ultimately enhanced economic and environmental health benefits across the region. Project impact will be measured with a survey conducted throughout the Northeast region in year 5 of the current project and year 4 of the proposed project.