NE1025: Biology, Ecology and Management of Emerging Pests of Annual Bluegrass on Golf Courses
- November 01, 2005 to September 30, 2011
- Administrative Advisor(s):
Richard C. Rhodes III
- NIFA Reps:
H. J. Meyer
Robert M. Nowierski
Statement of Issue(s) and Justification:Turfgrass is a valuable and rapidly expanding component of our urban and rural landscape. Turfgrass covers 12 million ha in the U.S. (Potter & Braman 1991) and includes over 60 million lawns and more than 16,000 golf courses (Emmons 2000). Golf courses are an important component of the turfgrass industry. They are a source of green space in the urban environment and offer recreation and enjoyment for approximately 36 million Americans. Golf courses also generate jobs, commerce, economic development, and tax revenues for communities throughout the U.S. A recent report by the World Golf Foundation stated that golf contributes $62.2 billion worth of goods and services each year to the national economy (www.golf2020.com).
Few turfgrass species can tolerate the intensive management regimes (e.g., low mowing heights, low fertility, frequent cultivation, etc.) implemented on putting greens, tees, and fairways. Annual bluegrass (Poa annua) and bentgrass (Agrostis spp.) are well suited to these locations but are prone to many diseases and insect pests. Although most pest problems can be controlled with chemical pesticides, the general public is becoming increasingly concerned about the potential for pesticide exposure and long-term effects to humans and pets, as well as the possibility of ground and surface water contamination. The extensive use of chemical pesticides to control turfgrass pests also can reduce profitability of golf course operations. An integrated approach to disease and insect management (integrated pest management or IPM) can help alleviate some of the public concern about pesticide use and benefit the golf industry by increasing the efficiency of pest control efforts.
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, part of a project funded by the NSF Center for IPM, included superintendents, university personnel, environmental and public health advocates, and representatives from the US Golf Association and the US EPA. The group discussed and prioritized key issues in IPM many of which are addressed in the current multistate turfgrass regional research proposal. Research and extension priorities cited by this group include (1) alternatives to current chemical pesticides, (2) forecast and sampling protocols for important pests of golf turf, and (3) a comprehensive Web-based treatment of golf turf IPM. For a complete summary of the focus groups' priorities refer to: http://northeastipm.org/ partners/priorities/turf2001.html. Our proposed research project will directly address these priorities as well as other gaps in knowledge and management practices associated with the annual bluegrass weevil (ABW) and anthracnose disease, two of the most important pest problems of annual bluegrass in the Northeast and Mid-Atlantic regions.
The importance of the work and the consequences if it is not done. Annual bluegrass is a common invasive species present on golf courses throughout the world. Biotypes of this species exhibit growth habits ranging from true winter annuals to long-lived perennials (Huff 2004). Annual bluegrass is often considered a weed by golf course superintendents, especially when it begins to encroach into newly seeded stands of creeping bentgrass (Agrostis stolonifera). Although some superintendents attempt to control annual bluegrass with herbicides, fumigants, or chemical growth regulators, these attempts often fail due to the competitive ability and prolific reproductive capacity of this grass species. In many cases, annual bluegrass becomes the dominant species in fairways and putting greens, and superintendents resort to managing it instead of the more pest-tolerant bentgrass species (Miltner et al. 2004). Annual bluegrass can provide an acceptable playing surface for putting greens and fairways when properly maintained, but this often requires extensive chemical inputs (Grant & Rossi 2005). Attributes of this species include its high tiller density, and tolerance of low cutting heights, shade and traffic. However, it is often maligned for its lack of stress tolerance, yellow-green color, prolific flowering habit, and its susceptibility to many diseases and insect pests (Beard 1973).
The maintenance of annual bluegrass on golf courses in the Northeast and Mid-Atlantic has become increasingly complicated by two emerging pests: the annual bluegrass weevil (Listronotus maculicollis) and anthracnose diseases caused by the fungus Colletotrichum cereale. The turfgrass anthracnose pathogen is commonly referred to as C. graminicola, a well-known pathogen of maize, but recent studies confirm that pooid-infecting isolates differ substantially from the maize pathogen, prompting the resurrection of the original name, C. cereale. Both pests can cause severe damage on annual bluegrass turf and can result in increased pesticide use and reduced golf-generated revenues. In severe cases, control of these pests depends almost entirely on synthetic pesticides. Reliance on multiple pesticide applications increases possibility of insects and pathogens developing resistance to these pesticides, as well as the cost of control. There is an urgent need to refine our understanding of the biology and ecology of these pests, to develop better IPM tools to assess and monitor their impact, and to discover and deploy alternative pest management practices whenever possible. By integrating these approaches, we seek to develop best management practices for the control of ABW and anthracnose on annual bluegrass, while promoting a model for environmental stewardship and cost effectiveness in other turfgrass habitats and highly managed ecosystems.
The annual bluegrass weevil is an insect of increasing concern in the northeastern U.S. where it is a notorious and damaging pest of close-cut annual bluegrass on golf courses and tennis courts. ABW injury to turfgrass was first reported in CT in 1931 (Britton 1932) and until the last 15 years has been concentrated in the metropolitan area of NY. Severe infestations are now being reported from all other states of the Northeast (DE, MA, ME, NH, NJ, NY, PA, RI, VT), west into Ontario and north into Quebec. It was problematic for the first time in MD last year, representing the southern front of its expanding range of impact in the Mid-Atlantic. Although not always present in turfgrass settings, the species has been reported from more than 40 states - therefore, the potential exists for significant spread of impact across a wide geographic range of the U.S. and Canada.
Every spring, superintendents contend with the movement of ABW adults from off-course overwintering sites to greens, tees, and fairways. As the insect completes two to three 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 annual bluegrass is least vigorous and at a competitive disadvantage during the summer months, which coincides with the peak period of ABW feeding activity. Currently, there are no effective control options other than pyrethroid insecticides that target adults. In the best-case scenario, control is achieved with one well-timed perimeter spray, but it is not uncommon for superintendents to make 2-5 applications per season. Because ABW control depends almost exclusively on pyrethroids, this species may be under strong selective pressure for developing resistance to this chemical class.
Anthracnose is the name given to leaf diseases that occur throughout the world on almost all turfgrass species. They are particularly severe on annual bluegrass and to a lesser extent on creeping bentgrass. The anthracnose pathogen may cause a foliar blight or basal rot of leaf and sheath tissue (Smiley et al. 2005). Superintendents have been challenged in recent years by the increased incidence and severity of anthracnose diseases on golf courses throughout the U.S. (Dernoeden 2000, Landschoot & Hoyland 1995, Vermeulen 2003, Wong & Midland 2004) and Canada (Hsiang & Goodwin 1999). It is probable that the increased frequency of anthracnose on putting greens is associated with the intensive management practices (e.g., low cutting heights, increased mowing frequency, reduced nitrogen fertility, verticutting, and the use of plant growth regulators) currently employed by superintendents to meet the ever-increasing expectations of the golfing public.
Superintendents struggling to control anthracnose diseases often rely heavily on fungicides for disease suppression. However, relying solely on fungicides to control anthracnose 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 applied too late to be effective. Because of the increasing use of fungicides to control anthracnose, 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.
If the proposed research on ABW and anthracnose is not conducted, the consequences will likely be (1) pest resistance development to pyrethroid insecticides and several of the anthracnose fungicide chemistries, (2) increased economic and environmental costs associated with the application of chemical pesticides used to control these pests, (3) decreased opportunities for the acceptance of new annual bluegrass varieties (should they be introduced into the marketplace), (4) reduced likelihood that anthracnose-resistant grass varieties will be developed and marketed, (5) loss of revenue in the golf course industry due to widespread turf failure, and (6) lack of an integrated chemical and biological management system for intensely managed turf.
Technical feasibility. All scientists involved with the ABW section of this project have experience with ABW and other turfgrass insects in studies that relate to morphology, reproductive biology, population ecology, phenology, degree-day modeling, dispersal, rearing, and various control alternatives (biological, cultural, chemical). The researchers involved with the anthracnose section of this proposal have been studying and publishing on anthracnose diseases and the population biology of C. cereale for several years. Many of the PIs have already shared isolates (NJ, PA, ON, CA) and data pertaining to the genetics (PA, NJ, ON) and pathogenicity of C. cereale (NJ, PA, ON). Management studies (cultural and chemical) have recently been initiated at several of the universities (PA, CA, NY, NJ, ON, CT) that are to participate in this project. Breeding programs in the region also have extensive collections of annual bluegrass (PA) and creeping bentgrass germplasm (NJ, RI) that will be shared and used in a coordinated fashion to determine the potential for genetic resistance to ABW and anthracnose. In addition, many of the PIs currently have Extension appointments and have extensive experience and successful track records in outreach and impact assessment.
Advantages of a multistate effort. Fungal and insect problems occur across state boundaries, so it is imperative that we develop control strategies that are appropriate for the broadest geographic region possible. In addition to enhancing protection of this extremely valuable commodity throughout the region, a multistate effort will increase the exchange of knowledge, experience, and techniques among many scientists who would not otherwise have a defined mechanism for cooperation. Individual efforts will be directed toward understanding the biology of these two pests. 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 beginning and conclusion of this project will provide a comprehensive evaluation of pest importance, impact, and management practices across the region. Division of labor according to the primary expertise of the involved labs will improve the quality of the specific studies, and the outcomes from the various labs will help other labs advance more quickly with their studies. This regional approach will allow us to further examine multilocational studies across the Northeast and Mid-Atlantic for such areas as a degree-day model for ABW, pathogenicity of different fungal strains that cause anthracnose, efficacy of biological and biorational control agents for the two pests, and insect and disease resistance of annual bluegrass cultivars. Bringing entomologists, pathologists, management specialists, and plant breeders together will result in a better understanding of the biology and control of these two pests, and will allow for more efficient screening of annual bluegrass cultivars with optimal resistance to both ABW and anthracnose. Finally, a multistate effort will allow scientists to refine knowledge of these two pests and develop a set of "best management practices" (BMPs) that will help practitioners successfully control both pests while reducing pesticide use. Project participants will relay detailed, relevant findings to practitioners though regional and national seminars, symposia, electronic newsletters (NJ, NY), annual research field days (all states), and multi-authored publications in a coordinated fashion.
Anticipated impacts. Our interdependent research strategy will lead to the improved exchange of information among turfgrass entomologists, management specialists, breeders, and pathologists in the Northeast and Mid-Atlantic. A publication containing BMPs for annual bluegrass will be developed and disseminated to turfgrass managers in the region via this multistate effort. This and other applied publications developed from this project will be posted on our Website. This 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 ABW and anthracnose on annual bluegrass with reduced pesticide inputs, and ultimately economic and environmental health benefits across the region. Project impact will be measured with a survey conducted throughout the Northeast region in year 1 and 4 of this multistate project.
Related, Current, and Previous Work:Critical review of the current turf regional project - NE-187. Bentgrass (Agrostis spp.) germplasm was evaluated in coordinated trials in several environments across the Eastern U.S. (PA, NJ, RI, NY, MD, MA) leading to the development of best management practices for reducing the environmental impact of pesticides and nutrients. These studies focused on bentgrass species on golf course fairways and putting greens in which annual bluegrass was considered an undesirable species. In reality, annual bluegrass is such a competitive species that it often becomes a major component of greens, tees, and fairways only a few years after bentgrass is established. As a result, superintendents throughout the Northeast and Mid-Atlantic often focus their management programs on maintaining annual bluegrass as a major component of their playing surfaces. In addition, improved annual bluegrass cultivars are being developed at Penn State with relatively high rates of consumer interest. Advances in turfgrass management made during the NE-187 project can now serve to guide the development of best management practices for annual bluegrass based on an improved understanding of the major insect and pathogen pests that occur on golf courses in the region.
Although the black cutworm was the focus pest of bentgrass in NE-187, ABW has emerged as a damaging pest of annual bluegrass on high maintenance golf course turf in the Northeast. This prompted studies that specifically addressed pesticide use against this insect. In response, field trials were conducted to evaluate the effectiveness of different non-chemical alternatives to combat ABW larvae (MA), with the conclusion that additional studies are necessary to refine the timing of applications. In addition, expertise on the manipulation, application and targeting of biorationals and biologicals to soil insect pests in turfgrass were developed through NE-187. This included insect growth regulators, fungal endophyte infection, spinosad, Bt, and entomopathogenic fungi and nematodes.
As a result of research conducted through NE-187, overall disease resistance in creeping bentgrass cultivars has improved. Research expertise gained through these collaborations can now be applied to annual bluegrass. Collections of C. cereale isolates made by plant pathologists in NJ, PA, ON, NY, MA, and CA will be analyzed for genetic relatedness to other Colletotrichum species and populations, and will be examined for resistance to all available fungicide chemistries. Additionally, virulent isolates from these collections can now be used to screen annual bluegrasses from the Penn State breeding program and creeping bentgrass from the Rutgers breeding program at multiple locations throughout the Northeast to identify germplasm that is resistant to both anthracnose and ABW.
Other related research - ABW. A series of separate studies over the last ten years has assessed the field efficacy of products for ABW control, including conventional and alternative insecticides, biorationals and biologicals. Results from 42 studies have been published in Arthropod Management Tests from 1994 to 2004 based on research conducted in MA, PA, and elsewhere in the Northeast. New studies were initiated in NJ in 2004. As part of broader studies in PA addressing the suppression of pests in grasses, trials have shown that pyrethroids, not neonicotinoids nor halofenozide, can consistently suppress ABW populations on golf courses (Heller, CRIS PEN03988 and PEN03655). The results of this work have reinforced the need for more studies to (1) identify alternatives to pyrethroids, (2) refine the timing of application in accordance with insect life stage, (3) compare and contrast efficacy on larvae versus adults, and (4) further pursue the potential of biorationals and biologicals.
Another study on Long Island, NY (Grant & Rossi CRIS NYC-106355) is assessing the feasibility of golf course pest management under three management approaches. Results are strengthening our understanding of the overall management system in which the major pests of annual bluegrass need to be controlled. Recent studies in MD (Frank & Shrewsbury 2004) are examining the role of conservation strips installed on golf course roughs. This work demonstrates how those habitats can be manipulated to restore predator/prey dynamics and be exploited as an ecologically based control measure for pests like ABW. Other research is identifying some of the key cultural conditions that impact ABW activity (MA), such as the impact of cutting height on larval activity and feeding behavior; this work indicates that larvae feed more on lower-cut grass, regardless of species. Studies on ABW population ecology have been relatively rudimentary until a new study was conducted in 2004-2005 to interpret the association between ABW and the golf course landscape through high-resolution population dynamics, directional movement of adults and overwintering behavior (Peck & Diaz 2005). Previous work has established general patterns of the number and timing of generations, and correlated degree-day accumulations and ABW development to create a basic model for management decisions (MA).
Other related research - Anthracnose. During the past ten years, the incidence and severity of anthracnose has increased on golf courses throughout the U.S., particularly in the Northeast and Mid-Atlantic. In many cases, epidemics were so severe that fungicides were unable to effectively control the disease even when used at labeled rates or at recommended intervals of application. Differences in fungicide efficacy from region to region led to the idea that variations in fungal strains may also be an important factor in anthracnose control. Some strain variation was apparent from early studies (Vaillancourt & Hanau 1992), and has been confirmed in more recent studies (Backman et al. 1999, Browning et al. 1999, Chen et al. 2002, Horvath & Vargas 2004, Crouch et al. 2005a, 2005b). It is now clear that isolates of the turfgrass pathogen do not fit within the species C. graminicola where they have been classified for more than 50 years (Crouch et al. 2005b). Instead, the species C. cereale was recently resurrected to include fungal isolates that are pathogenic to grasses within the Pooideae, such as annual bluegrass (Crouch et al. 2005a). Several research groups (NJ, PA, ON) have done preliminary greenhouse and laboratory studies on the differential pathogenicity and virulence of turfgrass-infecting isolates of Colletotrichum, but conclusive field inoculation studies have not been reported. Studies are now needed to describe the etiology, epidemiology, and population biology of the pathogen.
Certain management practices can enhance abiotic stress and may thereby predispose turf to anthracnose. These factors include low cutting height, increased mowing frequency, reduced nitrogen fertility, rolling, verticutting, topdressing with sand, and the use of certain plant growth regulators. Low cutting height is associated with increased severity of anthracnose on golf course greens (Backman et al. 2002, Uddin & Soika 2003). Increasing mowing frequency may further intensify stress due to increased compaction, wear, and wounding. Lightweight rolling to improve ball roll distance can reduce dollar spot on putting green turf (Nikolai 2005), but the effect of rolling alone or in combination with other factors on anthracnose is unknown. Similarly, verticutting to minimize organic matter accumulation and improve surface playing conditions can increase anthracnose severity compared to untreated turf (Uddin & Soika 2003). Factorial studies to examine the impact of multiple management factors (e.g., mowing frequency, height of cut, and other factors such as light weight rolling and verticutting) have not been conducted. Such studies are needed to evaluate cultural practices and to document their subsequent effect on anthracnose susceptibility and development.
Another practice to increase green speed (an important measurement of quality) is to limit nitrogen fertility. Insufficient nitrogen, however, can weaken turf and reduce its ability to recover from damage. Although low nitrogen fertility is generally considered to enhance anthracnose severity (Smiley et al. 2005), past research in this area has yielded differing results (Crouch et al. 2003, Danneberger et al. 1983). Coordinated, multiple regional trials are needed to refine our knowledge of the effect of nitrogen on anthracnose so that specific recommendations can be developed for superintendents.
Over the past few years, plant growth regulators (PGRs) have become widely used on putting greens to reduce vertical plant growth or seed production in annual bluegrass. PGRs such as trinexapac-ethyl have been reported to increase anthracnose on creeping bentgrass putting greens (Vincelli 1999) but to reduce disease severity on annual bluegrass greens (Crouch et al. 2003). Given these conflicting results, more research is needed to ascertain the impact of PGRs on disease development.
Despite efforts to reduce reliance of golf course superintendents on fungicides, they will remain an important tool for controlling anthracnose diseases. Fungicide efficacy trials conducted at several institutions in the region (NJ, PA) over the past five years have revealed that certain chemical families (e.g., DMIs, QoIs, benzimidazoles, and others) have more activity against anthracnose than others (i.e., dicarboximides and phenylpyrroles). These reports have been published in Fungicide and Nematicide Tests from 2000-2004. Unfortunately, the development of fungicide resistance to QoI, benzimidazole and DMI fungicides in the pathogen has complicated the chemical control of this disease (Avila-Adame et al. 2003, Wong 2003a, 2003b). As a result, chemical control options are now limited and research examining the efficacy of fungicide combinations, timing, and resistance management strategies needs to be conducted. Recently, the phosphonate fungicide chemistry has shown promise in suppressing anthracnose while improving the health and quality of annual bluegrass (Crouch et al. 2003). Fungicides in this group appear to elicit disease defense mechanisms in the plant and are therefore less likely to have issues with resistance. Additional research is needed to fully assess the potential benefits of phosphonate fungicides for the control of anthracnose.
- Fill critical knowledge gaps in our understanding of the biology, ecology, and impact of ABW and anthracnose associated with annual bluegrass on golf courses in the Northeast and Mid-Atlantic.
- Identify and develop new cultural, biological, chemical, and genetic control options for suppressing ABW and anthracnose on golf courses.
- Develop improved IPM decision tools for managing ABW and anthracnose on golf courses.
- Develop best management practices for annual bluegrass on golf courses that will help reduce the economic and environmental costs associated with pesticides currently used to control ABW and anthracnose.
Objective 1. Fill critical knowledge gaps in our understanding of the biology, ecology, and impact of ABW and anthracnose associated with annual bluegrass on golf courses in the Northeast and Mid-Atlantic.
Geographic distribution. We will establish the current geographical distribution of ABW (MA, MD, NJ, NY, PA, RI) and anthracnose (CT, MD, NJ, NY, ON, PA, RI) in golf course habitats within the Northeast and Mid-Atlantic. Distribution data will be contributed from all participants and coalesced in a common database. For ABW, data will be acquired from golf courses with known infestations to establish the geographic limits of this problem and to monitor for future expansion in the areas impacted. Detailed information on strain distribution of the anthracnose pathogen will be obtained using DNA fingerprint, microsatellite, and nucleotide sequence analysis (NJ, ON, PA). This will be used to expand the current database of over 1000 isolates collected and recently reported (Crouch et al. 2005a, 2005b).
Overwintering and reproductive biology. Overwintering biology of ABW will be described based on field studies (MA, NY). Field surveys and controlled experiments will elucidate and test factors that influence overwintering site preferences and success. Aspects of ABW reproductive biology that are linked to population development and habitat exploitation, including preoviposition period, oviposition rate, lifetime fecundity, reproductive diapause and oviposition behavior will be examined in tandem with studies on host plant resistance (MA, NY). It is currently unclear whether the turfgrass anthracnose pathogen undergoes sexual recombination. This will be examined in the field by looking for sexual reproductive structures throughout the region, by inference using molecular techniques, and experimentally using controlled matings (NJ). The overwintering biology and survival of C. cereale will be assessed in controlled environment and field studies (CA, CT).
Population biology and ecology. MA, NY and PA will establish the patterns of adult dispersal, population fluctuation and phenology. In a detailed multi-year study, the spatial, temporal and dynamic aspects of the relationship between ABW overwintering sites and developmental sites will be studied; this will include studies on directional movement of adults and population ecology to quantify variation in population fluctuations, generation time, number of generations, and timing of the life stages from site-to-site and year-to-year. This new understanding will enable us to establish more precise phenological indicators associated with ABW life history. We will continue to examine the population biology and ecology of the anthracnose pathogen on golf courses and in natural settings using the tools described above to determine relationships among fungal strains from different regions and from monoculture versus mixed grass populations (CA, CT, NC, NJ, PA, ON, RI). This goal can be accomplished only as a collaborative effort. Nearly a thousand isolates of C. cereale from different pooid hosts have been collected by collaborators on this proposal and additional strains are needed to expand this database and our current understanding of this diverse pathogen. Other resources that have been developed include two plasmid libraries of different C. cereale lineages, a cosmid library of approximately 4X genome coverage, a set of simple sequence repeat (SSR) clones, and characterized clones representing three distinct transposons that can be used for fingerprint analysis. These resources will be greatly expanded through the collaborative efforts of the participants on this project. Fungal isolates labeled with green fluorescent protein (GFP) have been made and confirmed to be pathogenic. More transformed isolates will be produced allowing for direct visualization of the infection process (CT, NJ). The pathogenicity and virulence of Colletotrichum isolates will be evaluated in the greenhouse, laboratory, and field. A standardized methodology will be developed by NJ and PA and shared with other collaborators in this project. A long-term goal of any comprehensive host/pathogen interaction project involves genomic investigations. As information from similar organisms becomes available and methodologies become simpler and less expensive, studies directed at examining host and pathogen gene expression become more approachable. For example, genomic investigations of other Colletotrichum species will aid the anthracnose work described here, and examinations of other grass hosts will benefit our work with annual bluegrass. Although we do not have specific plans for complete genome sequencing, we expect to begin investigations of the fungal and host plant genomes during the course of this project. These studies will complement ongoing and proposed studies by several groups toward the complete genome characterizations of C. graminicola and its host Zea mays.
Host plant selection. MD, NY and RI will determine adult oviposition and larval feeding preferences through controlled studies in the laboratory and greenhouse, with the aim of resolving lingering questions such as how much ABWs predilection for annual bluegrass is based on preference versus need. There is some evidence suggesting that the anthracnose pathogen shows host specificity at the level of fungal strains or lineages. This will be examined by correlating host plant information with molecular data from fungal isolates (NJ, PA, ON), and by using controlled inoculations in the greenhouse and field (NJ). We will also attempt to establish the role of Microdochium bolleyi in the development of anthracnose in annual bluegrass. This fungus has been frequently isolated from samples of annual bluegrass exhibiting symptoms of anthracnose in the Northeast, yet its role in the disease process as a pathogen, saprophyte, or potential biocontrol agent is unknown. Collaborators will send samples to NJ for isolation, identification, and evaluation as an inoculant in the greenhouse and field.
Objective 2. Identify and develop new cultural, biological, chemical, and genetic control options for suppressing ABW and anthracnose on golf courses.
New control options. We will expand our range of management alternatives by advancing new biological, biorational, cultural, and chemical control options for ABW (MA, MD, NJ, NY, PA, RI) and anthracnose (CA, CT, MD, NC, NJ, NY, ON, PA). New strains/species of entomopathogenic fungi and nematodes will be collected from golf courses throughout the region and shipped to NJ for pathogen isolation, identification, and maintenance. NJ will conduct more intensive pathogen surveys and determine the pathogenicity of isolated pathogens as well as commercially available biologicals and biorationals against ABW larvae and adults in laboratory bioassays. The most promising pathogens and biorationals along with new emerging synthetic insecticides will be tested against the spring and summer ABW generations in infested fairways and in hibernation sites on golf courses. Studies will be conducted to identify other cultural control methods that disfavor ABW while favoring natural enemies.
CT, NJ, NY, and PA will study the impact of management factors on the development of anthracnose in coordinated field studies. PA will evaluate nitrogen source and rate in mixed bentgrass/annual bluegrass greens, while NJ will continue its assessment of nitrogen in a factorial study with PGRs and verticutting. CT and NJ will collaborate on several PGR studies to ascertain the influence of seedhead suppressants and growth regulators on disease development focusing on component mixtures and timing regimes that could be used on annual bluegrass greens to improve efficacy and reduce fungicide usage. To determine the effect of mowing stress on anthracnose, NJ, NY, and PA will conduct several factorial studies in the field over the next four years. Although it is not feasible to repeat all mowing treatment combinations at all three locations, each participant will be responsible for completing specific sub-objectives, share data, and jointly develop BMPs for this segment of the project. Specifically, PA will examine mowing height and verticutting, NY will assess mowing frequency and cutting unit design (i.e., fixed vs. floating reels), and NJ will study the influence of mowing height, frequency, and light weight rolling on anthracnose in an annual bluegrass green. Poor water management may contribute to the rapid infestation of annual bluegrass in golf turf by C. cereale, and may affect the epidemiology of anthracnose. A study will be conducted in NJ to examine effects of different irrigation regimes (adequate, under, and over-irrigation) on the change in annual bluegrass and creeping bentgrass competition and anthracnose infection. Project participants will continue to collect isolates of the pathogen from throughout North America for use in laboratory, greenhouse, and field experiments. CT and NJ will maintain isolates for epidemiological, population biology, and management studies.
C. cereale could possibly serve to control annual bluegrass. While there are many challenges to this approach, it is nevertheless worth considering. Preliminary studies in NJ show that there are substantial differences in virulence among C. cereale isolates when inoculated to annual bluegrass. Isolates collected during the course of this study will be screened for use as biocontrol agents. We will also continue to examine ways to improve fungicide and insecticide efficacy, delay resistance, and reduce chemical use on golf courses. For ABW, widespread control failures and preliminary data in 2005 point to the development of resistance to pyrethroids . Pesticide combinations, timing regimes, and resistant management strategies will be assessed through the collaborative efforts of CA, CT, MD, NJ, and PA. Isolates of the anthracnose pathogen will be collected from annual bluegrass and bentgrass sites in the Northeast, Mid-Atlantic, and Western states where resistance is suspected and sent to CA to determine resistance frequency to the QoI, benzimidazole, and DMI chemistries. Molecular techniques (e.g., quantitative PCR) will be used to determine the frequency of fungicide resistance in populations of Colletotrichum from the field and to verify the mechanisms of resistance.
Conservation biological control. MA, MD and RI will identify ways to manipulate golf course habitats to attract and retain natural enemies of ABW. Predators and parasitoids will be identified through field sampling, and habitat manipulations will be designed to maximize the likelihood of attracting these natural enemies. Information from population ecology studies will help optimize this approach by precise placement of conservation beds / enhancement of natural enemies to target ABW at vulnerable stages. CT, NJ, NY, PA will continue to evaluate biological agents and biorational products for their ability to suppress anthracnose in the field. In-depth studies on the effect of phosphonates (e.g., phosphorous acid, phosphites, etc.) on plant health and anthracnose will be coordinated by PA in collaboration with NJ and CT.
Host plant resistance (CT, NC, NJ, NY, PA, RI). Improved cultivars of annual bluegrass have been developed through the breeding program at Penn State and many of these are currently undergoing field agronomic assessment in the Northeast. To date, however, these cultivars have not been widely evaluated for resistance to anthracnose and ABW. In parallel with the collection of in-depth biological information, it is imperative that annual bluegrass germplasm be rigorously evaluated for resistance/tolerance to these two pests. These studies will be initiated under controlled laboratory and greenhouse conditions, where evidence will be sought for a significant effect of cultivar on anthracnose and life history traits of ABW such as adult feeding, longevity, and fecundity, and larval development rate, size and success. Cultivars with tolerance to either pest will be further tested in the field at small- and large-plot scales, and under natural and artificial infestations. To date, seed from 12 diverse annual bluegrass lines are available for evaluation of pest resistance by members of this project. An early step in this breeding effort will be to develop a genetic linkage map of Poa annua populations resulting from crosses between anthracnose resistant and susceptible parents, then identify quantitative trait loci (QTLs) involved with anthracnose resistance (NJ, PA). These QTLs will then be used for rapid screening of germplasm in an annual bluegrass breeding program aimed at cultivar improvement. A genetic linkage map for creeping bentgrass has been developed and QTLs have been identified for dollar spot resistance (NJ) (Bonos et al. 2005). Researchers in NJ and PA will share technical expertise and methodology to successfully develop a genetic linkage map of Poa annua and identify QTLs. Although generally not as susceptible to anthracnose as annual bluegrass, bentgrass can be severely damaged by this disease. Therefore, the extent of genetic resistance to anthracnose in creeping bentgrass cultivars and existing germplasm sources from NJ, PA, and RI will be assessed and elite lines evaluated in the field by CT, MD, NC, NJ, NY, PA, and RI. Results from the evaluation of annual bluegrass and bentgrass germplasm for pest tolerance in this project will help golf course superintendents make more informed decisions on cultivar/species selection.
Objective 3. Develop improved IPM decision tools for managing ABW and anthracnose on golf courses.
Rearing techniques and economic thresholds. MD, NJ and NY will develop more efficient ABW rearing and propagation techniques. Improved techniques would facilitate laboratory and greenhouse studies, such as prescreening control products in lab bioassays or conducting small-plot field evaluations with artificially infested populations. Our overall approach would be based on experience with other grass-feeding insect pests and other weevil species such as black vine weevil. By evaluating different ways to maintain the life stages, we will develop a protocol that is the most reliable, efficient and consistent combination of scenarios for laying eggs, developing larvae and maintaining reproductive adults. MA and RI will conduct a series of studies to refine action and economic thresholds and the practical monitoring techniques that will make them accessible to practitioners.
Prediction models. MA, MD, NJ, NY, PA and RI will refine and validate a degree-day model and phenological indicators for predicting ABW phenology. Based on meteorological data from survey sites and previously established minimum developmental threshold, we will calculate the number of degree-days until the phenological events documented in the population studies. These data will be calculated for the spring and summer generations at both sites over four years. The thermal-based data (degree-days) will be compared with the calendar-based data (date) and other environmental indicators to determine which best predicts ABW phenology and is robust enough to overcome differences from year to year and site to site. Although previous efforts at developing a predictive model for anthracnose have met with limited success (Dannenberger et al. 1984), CA, CT, and NY will attempt to construct a model based on environmental parameters (humidity, temperature, soil moisture, leaf wetness period) and key management factors affecting plant vigor (fertility, mowing regimes, etc.). This forecasting model would use a disease severity index as a predictor of anthracnose development. Both the ABW and anthracnose models will be validated across the geographic range of the pests and across the broadest range of temperature and seasonality regimes where they currently occur, enlisting the help of all project participants.
Interactions between C. cereale and ABW have not been studied. The possibility that ABG can predispose annual bluegrass or serve as a vector to facilitate spread of C. cereale will be examined in small plots differentially infested with both the pathogen and the pest.
Objective 4. Develop best management practices for annual bluegrass on golf courses that will help reduce the economic and environmental costs associated with pesticides currently used to control ABW and anthracnose.
All participants will collaborate to develop a best management practices publication for annual bluegrass and its two key pests based on the findings from this multistate project. Our final meeting will consist of a formal symposium at either the annual meeting of the American Phytopathological Society, the Entomological Society of America, or the Crop Science Society. Papers will be submitted by all participants and select outside collaborators. These papers will be compiled as manuscripts into an edited publication on best management practices for the control of annual bluegrass on golf courses through better IPM of both pests. This and other publications developed from this project will be distributed by participating states and will be posted on our Website. Research results from this project will be extended to practitioners as they become available via regional workshops throughout the Northeast.
Measurement of Progress and Results:
- Publication of BMPs for annual bluegrass on golf courses, including new biological, biorational, chemical, cultural and ecologically based techniques for the control of ABW and anthracnose. This publication will be disseminated to turf managers in the Northeast and Mid-Atlantic, and will be placed on the project Website.
- New ABW and anthracnose resistant/tolerant cultivars of annual bluegrass and data on susceptibility of commercially available cultivars.
- New anthracnose resistant/tolerant cultivars of bentgrass and data on susceptibility of currently available cultivars.
- Analyzed results of practitioner surveys conducted throughout the Northeast and Mid-Atlantic in year 1 and year 4 of project. Document geographic distribution of pests, management practices used, and impacts of the multistate project.
- Data acquired and reported on biology and ecology of ABW and anthracnose.
- Efficacy data for biological, biorational, cultural, and chemical control of both pests.
- Improved sampling techniques and rearing procedures for ABW and new predictors of ABW phenology.
- New ABW pathogen species/strains.
- Better tools for assessing, monitoring, and predicting injury from ABW and anthracnose on annual bluegrass.
- Development of Website for project to include research progress updates, survey results, refereed and non-refereed publications, extension fact sheets and bulletins, conference proceedings, and minutes from regional project meetings.
- Results of project reported in year 2-5 to golf course managers via four real-time interactive Web casts to national/international audiences through the Golf Course Superintendents Association of America (a 22,000 member international organization).
- Conduct regional and national seminars at turfgrass conferences in years 2-5 to inform turf managers about the latest projects results, as well as research updates at state field days and electronic newsletters.
Outcomes or projected Impacts:
- Improved exchange of information among turfgrass entomologists, management specialists, and pathologists in the Northeast and Mid-Atlantic.
- Understanding the general biology and ecology of ABW and anthracnose, as well as the importance of improving management practices of annual bluegrass, should lead to enhanced control of these two pests with reduced pesticide inputs. This should result in cost savings to the golf course industry, improved plant health, and environmental benefits.
- Improved knowledge base of turf managers and extension agents resulting in changed management practices that are sustainable, cost-effective, and provide excellent control of anthracnose and ABW on golf course turf.
- Breeding programs begin focusing on anthracnose resistance in annual bluegrass (PA) and bentgrass (NJ), and ABW resistance in annual bluegrass (PA).
- Isolation and identification of C. cereale strains from North America (CA, CT, MD, NC, NJ, PA, ON), ABWs, and ABW pathogens from the Northeast and Mid-Atlantic (MA, MD, NJ, NY, PA, RI) for use in breeding programs, population studies, and management research.
- Website established by CT.
- Initial survey developed (CA, CT, NC, NJ, NY, PA, RI) and base line on anthracnose and ABW distribution and management information obtained from practitioners in the Northeast and Mid-Atlantic.
- Develop improved rearing procedures, (NJ, NY) to be shared and used by all project participants to more effectively screen biocontrol agents, biorational and chemical products and to evaluate turfgrass germplasm for susceptibility to ABW.
- Modify and share field inoculation procedures (NJ, PA) and isolates of Colletotrichum with all project participants to standardize procedures for biological, cultural, and chemical studies and to screen annual bluegrass and bentgrass germplasm (CA, CT, MD, NC, NJ, NY, PA, RI).
- Initiate infectivity/host specificity studies on C. cereale (NC, NJ, PA).
- Develop additional GFP-labeled isolates of C. cereale for use in direct visualization of the infection process (CT, NJ).
- Development of improved rearing procedures concluded.
- Initiate studies involving the overwintering biology and survival of C. cereale.
- Continued isolation and identification of Colletotrichum isolates, ABWs, and ABW pathogens for use in collaborative research studies.
- Complete factorial studies in several states examining the impact of nitrogen, mowing regimes, and cultivation practices on anthracnose.
- Identification of annual bluegrass germplasm from PA thought to have resistance/tolerance to anthracnose or ABW, as well as selections and cultivars of bentgrass from NJ and RI with suspected resistance to anthracnose provided to CT, NC, NJ, NY, PA, RI for greenhouse and field studies. 6. Initiate collaborative genomics studies on C. cereale (NJ, ON).
- Characterization of the role of plant growth regulators on anthracnose in the field.
- Conclude studies involving infection processes of C. cereale using GFP-labeled isolates.
- Data from field evaluations of annual bluegrass germplasm (for resistance to anthracnose and ABW) and bentgrass (for anthracnose) analyzed and shared with all project participants.
- Conclude initial infectivity/host specificity studies on C. cereale; determine whether extended studies are required.
- Follow up survey developed (CT, NJ, NY, PA, RI), conducted, and analyzed to ascertain impacts of ABW and anthracnose research on clientele.
- Action thresholds and appropriate monitoring techniques for ABW are refined and available for diffusion as part of extension materials.
- Assessments of plant growth regulator rate and timing on anthracnose development in the field completed.
- Development of initial anthracnose severity index model completed and validation of model initiated across the geographic range of C. cereale.
- Multi-year field evaluations of annual bluegrass and bentgrass germplasm tolerance to anthracnose and ABW analyzed and summarized.
- BMPs for annual bluegrass developed and disseminated to turf managers in the Northeast and Mid-Atlantic.
- Field report published for multi-year field evaluations of annual bluegrass and bentgrass germplasm tolerance to anthracnose and ABW.
- Evaluate progress of C. cereale genomics initiative and determine direction of research.
- Symposium on the biology, ecology, and control of ABW and anthracnose disease in annual bluegrass organized for either the annual meeting of the American Phyto-pathological Society, Entomological Society of America, and/or Crop Science Society.
Projected Participation:Include a completed Appendix E form
Outreach Plan:The annual meeting of NE-temp1041 serves as the mechanism to keep members and other interested parties abreast of current research related to the biology, ecology, and management of ABW and anthracnose and other pests of annual bluegrass, as well as related turfgrass activities (i.e., ancillary symposia, annual meetings, international exchanges). Information on this meeting and shared projects will be available on the NE-temp1041 Website. NE-temp1041 members will continue to make research results available through scientific journals, both refereed and non-refereed, extension bulletins, and national and international conferences and workshops. Information to the general public will be disseminated via publications in the popular press, magazines, oral and written presentations at workshops and at grower field days. A list of all publications developed by NE-temp1041 members will be updated annually and posted by CT on the NE-temp1041 Website in NIMSS (www.lgu.umd.edu).
Organization and Governance:The organization of the regional research project NE-temp1041 will be established in accordance with the format suggested in the "Manual for Cooperative Regional Research". One person at each participating institution or agency will be designated, with approval of the institution's or agency's director, as the voting member of the Technical Committee. Other individuals and interested parties are encouraged to participate as non-voting members of the committee. Each year, members will elect a Secretary. The Secretary, whose duties begin the following year, becomes Chair-elect in year two, followed by Chair the third year.
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s:/Richard C. Rhodes III
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