Source: TEXAS A&M UNIVERSITY submitted to
RESEARCH AND EXTENSION TO ADDRESS HERBICIDE RESISTANCE EPIDEMIC IN ANNUAL BLUEGRASS IN MANAGED TURF SYSTEMS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
EXTENDED
Funding Source
Reporting Frequency
Annual
Accession No.
1016398
Grant No.
2018-51181-28436
Project No.
TEX09736
Proposal No.
2018-03373
Multistate No.
(N/A)
Program Code
SCRI
Project Start Date
Sep 1, 2018
Project End Date
Aug 31, 2022
Grant Year
2019
Project Director
Bagavathiannan, M.
Recipient Organization
TEXAS A&M UNIVERSITY
750 AGRONOMY RD STE 2701
COLLEGE STATION,TX 77843-0001
Performing Department
Soil & Crop Sciences
Non Technical Summary
Problem and BackgroundKnown popularly as the 'Green Industry' or the 'Environmental Horticulture Industry', turf is a >$100 billion specialty crop industry in the US with about 50 million acres of managed turf operations nationwide (Haydu et al. 2006; SRI 2012). Turfgrass is the most widely grown irrigated crop in the US (Milesi et al. 2005). Turf is also among the most economically important specialty crops, with significant contributions to local economies and employment generation across the nation. Golf courses, athletic/sports fields, sod production operations, and residential lawns are the four major sectors of the US turf industry.Annual bluegrass (Poa annua L.), known commonly as Poa, is the most troublesome weed in managed turf systems throughout the US, revealed recently by a nationwide survey conducted by the Weed Science Society of America (Van Wychen 2016). This weed has grown to epidemic proportions in different turf systems, causing severe economic losses to the US turf industry. Annual bluegrass has high levels of genetic diversity and exhibits rapid adaptation to climatic gradients and management interventions. Annual bluegrass has a distinctly light-green color with white flower heads, and its presence is not tolerated in managed turf systems because of its severe negative impact on turf quality.Existing annual bluegrass management programs rely heavily on herbicides in all four major turf sectors. According to the International Survey of Herbicide Resistant Weeds, annual bluegrass ranks third among all herbicide-resistant weed species globally, with resistance to at least 9 different herbicide sites of action (Heap 2018). This includes resistance to all major herbicides used in turf systems such as photosystem II-, acetolactate synthase (ALS)- and mitosis-inhibiting herbicides. Additionally, annual bluegrass resistance to glyphosate has been reported (Brosnan et al. 2012; McElroy et al. 2013). Evolution of multiple herbicide resistance in this species is a serious issue as this trend has been quickly removing important herbicide options from the turf manager's toolbox.There is a critical need for developing sound best management practices (BMPs) based on a better understanding of the ecology and biology of annual bluegrass, current levels of herbicide resistance, and the nature and characteristics of resistance evolution and spread in this species. Limited information is available on the longevity of annual bluegrass seed in the soil. A thorough knowledge of seedling emergence patterns and environmental drivers governing emergence is yet to be developed, but will directly inform appropriate management timing. Such information can be linked with weather forecasts to provide seedling emergence advisories. Moreover, a thorough understanding of phenological development as influenced by environmental variables, and knowledge of demographic parameters such as fecundity will be beneficial.An important lesson from herbicide resistance management in agronomic crops is that developing and implementing BMPs that do not consider human and social dimensions of herbicide resistance are ineffective. A robust integration of human and social dimensions with the biophysical aspects of herbicide resistance is critical in innovating effective weed management approaches (Ervin and Jussaume 2014; Ervin and Frisvold 2016). The herbicide resistance epidemic in annual bluegrass in managed turf systems has likely resulted from the interaction of biophysical and social (behavioral) systems. A turf manager's decision to rely on a narrow spectrum of herbicides for weed control may be influenced by socio-economic factors, such as relative prices and personal values. Thus, to develop effective annual bluegrass resistance management, we must understand and address the various socio-economic and biophysical factors that serve as barriers to BMP adoption.Project objectives and supporting hypotheses1) Conduct surveys and document the extent of annual bluegrass susceptibility/resistance to key turf herbicides and develop methods for rapid resistance detection [Hypothesis: annual bluegrass resistance is prevalent in managed turf systems], 2) Establish physiological and molecular mechanisms of resistance prevalent in annual bluegrass across a regional scale [Hypothesis: there is a significant presence of non-target site resistance in annual bluegrass populations], 3) Generate information to fill critical knowledge gaps on the biology and ecology of annual bluegrass [Hypothesis: annual bluegrass exhibits prolonged seed persistence in soil with extended emergence periodicity], 4) Evaluate and optimize innovative weed management options for integration [Hypothesis: novel management practices can be optimized to provide detrimental impact on weed growth and seed production], 5) Survey turfgrass managers to identify socio-economic and other barriers to the adoption of herbicide resistance BMPs [Hypothesis: a thorough socio-economic investigation will help identify factors influencing weed management decision making by turfgrass practitioners], 6) Develop a user-friendly bio-economic decision-support tool for facilitating the implementation of BMPs [Hypothesis: decision-support tools will allow for easy visualization of the impact of various management options on long-term economics, weed population size and risk of resistance over short-term returns], 7) Develop and deliver an extension program for sustainable management of annual bluegrass [Hypothesis: robust outreach programs that utilize advanced tools will be effective in promoting BMP adoption], and 8) Provide educational opportunities to train the next generation of research and extension scientists and turfgrass practitioners [Hypothesis: involving undergraduate researchers, graduate students, and postdoctoral scholars in research and extension activities will provide adequate training in preparing them for tackling similar issues in future].Stakeholder involvementThe team recognizes the vital need for engaging stakeholders in defining the problem and integrating their experiential knowledge into BMP strategies. This project has been developed based on critical research and extension needs identified by various stakeholders in the managed turf industry. These include: regional and national turf industry organizations, turfgrass sod producer groups, golf course superintendents, athletic turf managers, and scientists-at-large, including representatives from the global Herbicide Resistance Action Committee (HRAC) and the Weed Science Society of America (WSSA). A stakeholder advisory panel has been formed involving key personnel from the above sectors. A detailed stakeholder engagement plan has been developed to ensure sustained engagement of stakeholders throughout the project development, implementation, and evaluation phases.Broader impacts of this proposalThe products and deliverables of this proposal are expected to have a tremendous impact on the broader turfgrass industry across the nation, including the states and regions not directly represented in the proposal. The socio-economic issues affecting weed management decision-making and adoption of BMPs are comparable in those areas. Most of the non-chemical tactics to be optimized and the BMPs to be formulated can be applied more broadly for the management of other turf weeds as well. Thus, the solutions to be developed in this project will benefit herbicide resistance management in turf weeds nationwide. Additionally, the proposed outreach activities will develop a fundamental understanding among the broader stakeholders of pesticide resistance evolution in any biological organism and promote sustainable IPM practices for the management of all turf pests (weeds, diseases, insects, and nematodes).
Animal Health Component
0%
Research Effort Categories
Basic
25%
Applied
50%
Developmental
25%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2132130310040%
2132130114025%
2132130107015%
2132130104010%
2132130308010%
Goals / Objectives
The short-term goal of the project is to develop knowledge and tools to facilitate the development, dissemination and adoption of BMPs for tackling annual bluegrass herbicide resistance in managed turf systems, through a coordinated, multi-institutional and inter-disciplinary approach. The long-term goal of the project is to improve the economic profitability as well as environmental and social sustainability or resilience of managed turf systems through implementation of sound weed management practices.
Project Methods
Field activities of this project will be conducted in 13 different states across the nation: TX, MS, AL, GA, SC, FL, TN, NC, VA, OR, IN, NJ, and PA, representing different plant hardiness zones relevant to warm-season as well as cool-season turfgrass systems. The socioeconomic specialists (Drs. Ervin and Frisvold) are located in OR and AZ, respectively. The project locations were chosen carefully such that the activities carried out yield the largest and most wide-reaching impact. Field surveys will be carried out to collect annual bluegrass samples for subsequent resistance evaluations. To achieve a representative sampling across the study locations, the area will be divided into five zones spanning across different states, based on the USDA plant hardiness map. Susceptibility/resistance evaluations will be conducted under greenhouse conditions; a consistent environmental condition of 30/25 C day/night temperature and 14 hr photoperiod will be followed. Evaluations will be conducted for the most commonly used ALS- (trifloxysulfuron and foramsulfuron), EPSPS- (glyphosate), PSII- (atrazine, simazine, and amicarbazone), and mitosis- (prodiamine and pronamide) inhibiting herbicides.To assess the potential for herbicide-resistant annual bluegrass to spread from seed production fields, we will test annual bluegrass seed from seed cleaners (weed seed removed from the lots after harvest, but before seed lot testing) and seed lots tested prior to retail distributions (i.e. certified seed lot). Rapid diagnostic assays will be developed for annual bluegrass resistance to the ALS-, EPSPS- PS II- and mitosis-inhibitor herbicides commonly used in turf systems. Two different approaches (agar culture as well as leaf-tissue incubation) that have been currently investigated by Co-PD Brosnan and Co-PD McCarty will be further improved in this project.Target-site (TSR) as well as non-target-site (NTSR) mechanisms of resistance will be tested using established methods. In annual bluegrass, TSR is known to occur for ALS-, PSII- and mitotic-inhibiting-herbicides. SNP target-site mutations will be identified in the samples using cDNA and allele specific primers to separate target-site genes from homeologous genes. NTSR can be endowed by reduced absorption, translocation and/or enhanced metabolic detoxification by the R individuals. Experiments will be conducted to elucidate NTSR mechanisms for ALS- and PSII-inhibitor herbicides as well as glyphosate. Following initial resistance screening, a subset of R populations (sampled as in TSR studies) spanning the study region will be selected to investigate any differences in absorption (foliar as well as root), translocation and metabolism.Several experiments will be conducted to further our understanding of the ecology and biology of annual bluegrass. Annual bluegrass seedbank persistence will be evaluated using a classical seed bag burial experiment in each of the five target zones. Annual bluegrass seedling emergence will be monitored in the four turfgrass systems in each of the five hardiness zones across a two-year period. In each hardiness zone, 2 distant sites will be identified for each turfgrass system (as above) (thus, a total of 20 site-years per system across the country). Further, a common-garden study will be conducted across seven locations, to evaluate growth cycle, time taken for different developmental stages as influenced by the environment, as well as specific traits that might be favoring adaptation. In each garden, annual bluegrass originated from 10 different locations (2 distinct sites in each of the five zones) will be compared.Experiments will also be conducted to evaluate and optimize innovative options for annual bluegrass control. These include non-synthetic compounds, fraze mowing, grass species and variety selection, mowing regime and grass-clipping removal, and irrigation and nutrient management. The non-synthetic compound evaluations will include Fiesta®, Thaxtomin-A®, Civitas®, X-Poa®, corn gluten meal (fall preemergence), concentrated acetic acid (40%), baking soda, hydrated lime, and a high rate each of zinc and ferrous sulphate, applied at three different growth stages (5-7 cm tall seedlings, peak tillering/vegetative growth stage, and early flowering stage), on four turfgrass species important to each location. Fraze mowing studies will be conducted in already established turf facilities in two locations, Knoxville, TN and Milton, FL, over a two-year period. Treatments will include a factorial combination of two different turfgrass species suitable for fraze mowing (bermudagrass and zoysiagrass), three mowing timings (May, June, and July), and three mowing depths (0, 1.5, and 3 cm).Laboratory (Clemson and Purdue), greenhouse (Clemson) and field experiments (all locations) will be conducted to understand the importance of turfgrass species and variety selection as a cultural tactic for annual bluegrass management. Laboratory assays will be conducted in Petri dishes to determine potential allelopathic activity of three popular varieties each of four warm-season turfgrass species (bermudagrass, centipedegrass, zoysiagrass, and St. Augustinegrass) and four cool-season turfgrass species (Kentucky bluegrass, perennial ryegrass, tall fescue, and strong creeping red fescue) on annual bluegrass seed germination and seedling growth. Field experiments will be conducted in the participating states to study the impact of mowing regime (height and frequency) and grass-clipping removal (thereby reducing seed addition to the soil seedbank) on annual bluegrass population size over a three-year period. A separate field experiment similar to that of the mowing/grass-clipping removal study will be conducted at the participating locations over a two-year period to evaluate the impact of irrigation and fertilization on annual bluegrass. Treatments will include a factorial combination of two irrigation regimes (field capacity versus gravitational), two sources of nitrogen (standard and a slow-release formulation), three rates of N (0.5, 1, 2X for each species), and three rates of P (0.5, 1, 2X for each species).A socio-economic analysis will be conducted to identify major barriers that are impeding best management practice (BMP) adoption by turf practitioners. Five analytical steps are planned: 1) conduct focus groups, 2) develop a list of turf managers, 3) develop a survey instrument, 4) implement the survey in a mixed mode fashion, and 5) perform univariate and multivariate analysis of the survey dataset. Economic studies will be conducted to collect data and build dynamic programming models to measure the long-term returns to resistance management. These models will be used to estimate the net present value of costs of annual bluegrass control under proactive resistance management strategies compared to reactive strategies that do not manage to delay resistance. Additionally, a user-friendly, web-based annual bluegrass management decision support tool will be developed and implemented. This tool will allow the user select and evaluate a combination of different weed management options for their impact on resistance risk. A herbicide site of action and management diversity calculator will indicate the long-term sustainability of the management programs tested.A strong outreach and education plan is in place. The Extension and outreach responsibilities of this project will focus on information transfer as well as implementation of BMP tactics by turfgrass managers that will reduce the risk of herbicide resistance while simultaneously improving weed control outcomes. The proposed educational plan includes incorporating direct classroom teaching in turfgrass management and weed science courses taught by the team members in various institutions, as well as training undergraduate researchers, graduate students, and postdoctoral scientists.

Progress 09/01/20 to 08/31/21

Outputs
Target Audience:Professional turfgrass and property managers, including golf course superintendents, lawn care operators, Perennial Ryegrass Growers Association, Ryegrass Commission, Tall Fescue Commission, Fine Fescue Commission and United States Golf Association Research Committee, sports field managers, growers, seed testing services, seed salesmen, seed/sod producers, agronomy field researchers and university scientists. The larger turfgrass and landscape industry is also a key stakeholder group, including industry suppliers, master gardeners, agrochemical distributors, consultants, industry advocates, professional associations. Changes/Problems:Similar to last year, we faced various challenges due to the COVID-19 pandemic. Delays and loss of efficiency/resources were inevitable with several of the project objectives. Additionally, there were fewer new students/research staff onboard and maintenance & repair works were delayed due to staff shortages. Overall, social distancing and limited work hours/scheduling with greenhouse and lab experiments meant that certain tasks could not be completed in a timely fashion. There was a substantial delay and difficulty in collecting plant samples due to moderate stakeholder participation as well as the limited availability of support personnel. Preemergence herbicide screenings as well as non-target site resistance mechanism evaluations were delayed. There were also delays in compiling and developing outreach material as well as educational videos due to substantial data backlogs. It has been a challenge to write/assemble those documents given the current challenges and resource limitations. Most of the collaborating institutions are slowly transitioning back to normalcy and hoping that the next fiscal year will be much better in terms of research staff availability and research supply logistics. Some changes were introduced to certain objectives to ensure that proper methodology is followed and the deliverables are met. The number of samples for resistance survey were reduced both due to COVID related difficulties in gaining access to the facilities as well as the need for placing more resources to the screening pipeline; yet sufficient number of samples are targeted across the different agroclimatic zones. It is also expected that many BMP documents will be written during the final phase and after the project has ended. We will be requesting a no-cost extension so that we can adequately complete the delayed activities. What opportunities for training and professional development has the project provided?This year, the project has trained (full-time or part-time) 25 undergraduates, 22 graduate students, 10 postdoctoral research assistants, 3 scientists, 7 technical staff and 1 administrative staff member on various aspects of research and project management. The undergraduate students learnt about experimental design, research plot installation and maintenance and hands-on research experience while assisting graduate students and postdoctoral scientists. The graduate students and post-docs acquired knowledge on standard operating procedures for greenhouse and growth chambers, techniques on the identification of potentially resistant annual bluegrass populations, herbicide susceptibility/resistance, resistance screening methodology, absorption, translocation, and metabolism studies useful in NTSR mechanisms, molecular evaluations and screening, germination tests/ techniques, procedure for turf species leaf clipping extracts, overseeding techniques, calibration and operation of small research plot equipment, operating and recovering data from weather data loggers, compiling generated data and creating visuals, developing dynamic programming models for resistance management, data collection, statistical analysis (seedling emergence, cumulative emergence curves), and summarizing research findings for peer-reviewed scientific journals. All research and technical staff received training in herbicide mode-of-action, tissue culture techniques, new methods of seed harvesting, cleaning, and herbicide screening procedures. How have the results been disseminated to communities of interest?Project results have been disseminated to the broader clientele through various extension avenues, social media, including professional conferences, society meetings, extension articles and trade journal articles, presentations, posters, publications, peer review papers, webinars, social surveys, seminars, virtual and in-person field days, and farm visits. Video footage from various locations are being utilized to produce educational videos for training purposes. Our social media presence has grown through twitter {Twitter handle @ ResistPoa) and ResistPoa.org website as a portal for stakeholders to interact and exchange knowledge. Preliminary information on the collection of potentially resistant populations has been incorporated into state and multi-state Extension/outreach presentations for turfgrass professionals. What do you plan to do during the next reporting period to accomplish the goals?The team will continue to make progress on the activities originally outlined FY2022. Over the past two years, major focus has been placed on experimental design and intensive data collection. Many of the project objectives are wrapping up data collection and slowly transitioning towards data organization, curation and analysis. A couple of research manuscripts have already been produced in the current reporting year and more emphasis will be placed on scientific as well as outreach publications in the next year. The proposal for a "Poa Panel' at the Golf Industry Show-2021 has been accepted where the best management practices developed by this project will be delivered to a national audience.

Impacts
What was accomplished under these goals? Obj 1a. Resistance Surveys: The pending screening with postemergence herbicides for Texas and Florida populations of Poa has been completed and advanced to dose-response experiments and further testing. Objective 1b. Resistance screening: PRE and POST herbicide resistance susceptibility/ resistance evaluations were completed using whole-plant dose-response experiments, to identify resistant populations for further evaluation. Replacement series experiments were conducted to ascertain growth rate differences and competitive nature of Poa biotypes. Objective 1c. Testing planting seed sources: Herbicide resistance screening has been initiated in a small number of populations that had sufficient seed. Objective 1d. Rapid diagnostic assays: We have identified a candidate herbicide for rapid diagnostic assay to screen Poa biotypes with increasing concentrations of indaziflam. Using IC75 value, we identified a discriminatory dose of indaziflam that could separate resistant and susceptible biotypes. Acquired biotypes with known resistance will be used as standards in the assay development. Objective 2a. Target-site resistance (TSR) and genetic relationships: We have completed target-site sequencing and mutation detection for all the targets using a semi-automated pipeline developed by us, which is cost effective and accurate for throughput analysis of majority of known target site mutations in Poa. A total of 136, 104, 85, and 81 Poa populations were sequenced for the ALS, psbA, EPSPS, and α-tubulin genes, respectively. Objective 2b. Non-target-site resistance (NTSR): All methodologies and techniques were validated for NTSR confirmation. Populations with putative NTSR for PS-II, ALS or EPSPS were advanced to absorption/translocation/metabolism experiments. Currently these populations are maintained for seed increase to meet the sampling needs of these experiments. Objective 3a. Seedbank persistence: Seed bags were retrieved for the six-month interval, and germination and viability assays have been completed for all 7 locations following standard protocols. Assays on the one-year retrieval timing will begin this fall Objective 3b. Seedling emergence: First and second year of data collection are already completed for assessing Poa annua seedling emergence patterns in naturally infested areas. Additional plots have been established to observe Poa seedling emergence in some southern locations. Corresponding weather data were also collected in each location. Data analysis is being carried out for the first two years of seedling emergence data. Objective 3c. Phenology and adaptive traits: Poa seed sourced from 10 different states were grown in a greenhouse in College Station to eliminate maternal environmental effect. Common garden experiments were established in seven states. A number of morphological measurements were carried out throughout the growth cycle. Biomass and seed were harvested and seed trait characterization is currently underway. Objective 4a. Evaluation of non-chemical products and alternative compounds: A first run of experiments were carried out in areas with natural infestations of annual bluegrass using 10 different non-synthetic herbicide products to evaluate their field efficacy in controlling annual bluegrass, and optimize application rates. Objective 4b. Fraise mowing:The fraise moving experiments were repeated (second experimental run) in Tennessee and Florida. Further, a qualitative study was conducted in 2021 where eight turfgrass managers were interviewed in order to understand barriers and challenges to fraise mowing application. Turfgrass managers had positive views of fraise mowing despite challenges such as high cost, labor, area closure, and debris removal. Objective 4c. Grass species and variety selection: The soil leachate studies have been completed in all four participating states and data are currently being analyzed. Two rounds of leaf extract evaluation trials have also been completed. Experiments on Poa seed germination test, seedling emergence suppression, and relative differences in establishment in turfgrass stands have been completed. Objective 4d. Mowing regime and grass-clipping removal: To quantify and evaluate the influence of leaf clip collection after mowing on the return of viable annual bluegrass seed to turfgrass stands, Poa seed heads were collected at various growing degree day timings across locations throughout winter and spring. Viability of the collected seed was determined using standard methods. The seed germination tests for the second run are being conducted. Objective 4e. Irrigation and nutrient management: Experiments were conducted to evaluate the effects of irrigation frequency and mineral nutrient fertilization on annual bluegrass establishment in cool and warm season turfgrasses. Six greenhouse experiments (two at Oregon State, four at Rutgers) were conducted to evaluate the effect of various phosphorus rates on annual bluegrass in competition with perennial ryegrass and creeping bentgrass. Experiments to evaluate the effects of nitrogen fertilizer rate and timing on annual bluegrass incidence in Kentucky bluegrass and perennial ryegrass have been initiated. Objectives 5a, 5b Socio-economic investigations: To identify major barriers impeding BMP adoption for integrated weed management by turf practitioners, focus group discussions were conducted with each turfgrass sector (golf course, sports field, lawn care, and seed/sod production), lists of growers and managers in the target turfgrass sectors were developed, an online survey instrument for turfgrass managers in sports, golf and sod/seed production, turfgrass production industry were developed, and the data were analyzed using univariate and multivariate methods. Additional focus group discussions with lawn care operators from (1) Far West, (2) Texas, (3) Deep South, and (4) Northeast/Midwest have been completed and the fifth one is scheduled for November 2021. Objective 6. Decision-support tool: An extensive data mining exercise was recently completed to extract herbicide options and use information for annual bluegrass control in various turf systems. This database is currently being verified by university experts for accuracy and comprehensiveness. Further, a draft wireframe for the web application has been initiated. Objective 7. Outreach: ResistPoa.org website portal (currently 898 followers) for stakeholders to interact with Extension and Educational material has been constantly updated and maintained. There are currently ~70 documents that can be sorted by turf type scenario (cool-season, warm-season, or transition zone), control method (biological, chemical, or cultural), and state (50 US states, international, or all). We also updated the herbicide classification poster to reflect the 2020 changes to classification scheme by HRAC and WSSA. Objective 8. Education: Materials for classroom education for universities, scientists and extension personnel are being developed. An updated annual bluegrass handbook and educational videos are in the making.

Publications

  • Type: Journal Articles Status: Submitted Year Published: 2021 Citation: Carroll, D., J.T. Brosnan, J.D. McCurdy, E.B. De Castro, A. Patton, W. Liu, J. Kaminski, K. Tang, P. McCullough, and D. Westenbury. 2021. Viability of Poa annua Seed During Spring in the Eastern United States. Crop, Forage, & Turfgrass Management (submitted).
  • Type: Journal Articles Status: Submitted Year Published: 2021 Citation: Allen, J., D. Ervin, J.T. Brosnan, J.D. McCurdy, et al. Turfgrass Industry Views on Managing the Threat of Herbicide-Resistant Poa annua. Weed Technology (Submitted).
  • Type: Journal Articles Status: Submitted Year Published: 2021 Citation: Kowalewski, A., A. Cain, E. Braithwaite, B. McDonald, C. Schmid. 2021. Nitrogen Fertility Rates Affecting Weed Population Dynamics in a Perennial Ryegrass Stand in Western Oregon. International Turfgrass Society Research Journal (Submitted).
  • Type: Journal Articles Status: Submitted Year Published: 2021 Citation: Cain, A., E. Braithwaite, B. McDonald, A. Kowalewski, and M. Elmore. 2021. Irrigation frequencies and reference evapotranspiration replacement effecting annual bluegrass populations in western Oregon. International Turfgrass Society Research Journal (Submitted).
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Carroll, D.E., J.T. Brosnan, J.B. Unruh, C.A. Stephens, C. McKeithen, and P. Boeri. 2021. Non-chemical control of annual bluegrass in bermudagrass via fraise mowing: efficacy and barriers to adoption. Sustainability. https://doi.org/10.3390/su13158124
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Brosnan, J.T., J.J. Vargas, B. Spesard, D. Netzband, J.M. Zobel, J. Chen and E.L. Patterson. 2020. Annual bluegrass (Poa annua) resistance to indaziflam applied early?postemergence. Pest Manag Sci, 76: 2049-2057. doi:10.1002/ps.5740
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: McNally, B., M.T. Elmore, A. Kowalewski, A. Cain, E. Braithwaite, J. Murphy, S. Murphy. 2021. Effects of phosphorus levels on annual bluegrass encroachment in creeping bentgrass during establishment. Proceedings of the Northeastern Plant Pest and Soils Conference.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Osburn, A., Grubbs, B., Hathcoat, D., Askew, S., McCarty, L.B, Elmore, M.T., Brosnan, J., McCurdy, J.D., McCullough, P., Unruh, B., Gannon, T., Patton, A., Kaminski, J., Kowalewski, A., McElroy, J.S., Bagavathiannan, M.V. 2021. Multi-State Research Evaluating Seedling Emergence and Herbicide Resistance Epidemic in Annual Bluegrass (Poa annua L.) in Managed Turfgrass Systems. In: Proceedings of the ASA-CSSA-SSSA Annual Meeting, Phoenix, AZ.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Osburn, A., R. Grubbs, M. Bagavathiannan. 2021. Understanding Seedling Emergence Patterns of Poa annua in Two Climatic Zones in Texas. In: Proceedings of the Southern Weed Science Society Virtual Annual Meeting.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Osburn, A., R. Grubbs, M. Bagavathiannan. 2021. Seedling Emergence Patterns of Poa annua in Texas. 2021. In: Proceedings of the Weed Science Society of America Virtual Annual Meeting.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Kankarla, V., J. McCurdy, E.B. de Castro, D. Hathcoat, R. Grubbs, M. Bagavathiannan. 2021. Developing a decision-support tool for facilitating the selection of diverse herbicide mode of action in turf. In: Proceedings of the Weed Science Society of America Virtual Annual Meeting.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Cain, A., C. Mattox, A. Kowalewski, B. McNally, and M. Elmore. 2020. Establishment competition of perennial ryegrass and annual bluegrass when fertilized with various rates of phosphorus. ASA, CSSA and SSSA International Annual Meetings. Phoenix, AZ.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: McNally, B., M. Elmore, A. Kowalewski, A. Cain, and E. Braithwaite. 2020 Effects of mowing height and irrigation frequency on annual bluegrass in perennial ryegrass. ASA, CSSA and SSSA International Annual Meetings. Phoenix, AZ.
  • Type: Other Status: Published Year Published: 2020 Citation: Carroll, D.E., Brosnan, J.T., McCullough, P.E., McCurdy, J.D., Patton, A.J., Castro, E.B., Liu, W. 2020. When is Poa annua seed most germinable in spring? Golf Course Management 88(2):79.
  • Type: Other Status: Published Year Published: 2020 Citation: Castro, E.B., McCurdy, J.D. 2020. Herbicide Classification Poster. Available at: www.resistpoa.org
  • Type: Other Status: Published Year Published: 2020 Citation: McCurdy, J.D. 2020. The ResistPoa Project Enters a New Phase. Mississippi Turfgrass Magazine.https://theturfzone.com/mta/?ascat=73&sub=issue&issue_id=4425&rti=true&rel=1
  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Cain, A. Non-chemical approaches to managing annual bluegrass (Poa annua L.). 2020. Masters thesis. Oregon State University. 59 p.
  • Type: Other Status: Published Year Published: 2020 Citation: McCurdy, J.D., J. Brosnan, J.S. McElroy, T. Gannon, J. Kaminski, D. Ervin, J. Allen, and B. Grubbs. 2020. ResistPoa Webinar. Online. Agenda.


Progress 09/01/19 to 08/31/20

Outputs
Target Audience:Professional turfgrass and property managers, including golf course superintendents, lawn care operators, Perennial Ryegrass Growers Association, Ryegrass Commission, Tall Fescue Commission, Fine Fescue Commission and United States Golf Association Research Committee, sports field managers, growers, seed testing services, seed salesmen, seed/sod producers, agronomy field researchers and university scientists. The larger turfgrass and landscape industry is also a key stakeholder group, including industry suppliers, master gardeners, agrochemical distributors, consultants, industry advocates, and professional associations. Changes/Problems:We faced various challenges due to the COVID-19 pandemic this year. There was a substantial delay and difficulty in collecting plant samples and conducting greenhouse experiments due to moderate stakeholder participation as well as support personnel availability. Social distancing and limited work hours/scheduling with greenhouse and lab experiments meant that certain tasks could not be completed in a timely fashion. Delays with planting and conducting greenhouse screening especially in the more southern locations such as TX led to poor establishment and growth of Poa seedlings, especially the late-planted ones. It was decided to redo screening of the last batch in order to verify results and collect quality leaf samples for molecular analysis. The PRE herbicide screening also needed to be postponed to fall 2020. Delays and loss of efficiency/resources were inevitable with many of the project objectives. We also made some changes to certain experiments. Of the target resistance surveys, we decided to reduce the number of surveyed sites, while still achieving good sampling distribution. Seed quantities that we were able to harvest from the survivors were much lower than what was originally anticipated. This means that the populations selected for dose-response and NTSR will need to be grown again for seed increase prior to moving forward with dose-response assays. This unexpected setback is expected to substantially delay the timeframe for dose-response evaluations and NTSR investigations. Moreover, when the proposal was submitted, the team was unsure of the total number of populations to be subjected to NTSR assays. After the screening results and conducting preliminary methodology standardization, it became obvious that only about 20 to 25 populations can be effectively handled within the available resources for all three NTSR mechanisms (absorption, translocation, and metabolism), multiple herbicide targets, multiple plant tissue parts, multiple harvest times, replications, and runs. We noticed especially in cooler locations that Poa seedling emergence occurred outside of the traditional emergence window. As a result, we decided to add more sites and plots to investigate the influence of seasonal onset and/or seedbank depletion on Poa annua seedling emergence. We also modified the protocol for evaluating germination in Petri dishes by drawing subsamples from each plot to reduce variability in the experiment and improve consistency of the data. As foreseen during the proposal process, it takes time to generate results from the ongoing field and lab objectives of the ResistPoa project; thus, the majority of the BMP development and dissemination are expected to happen during the later phases of the project. We would like a host of outreach material developed during the 2021 and 2022 cycles. However, it will be a challenge to write/assemble those documents on such a compressed timeline, given the current resource limitations exacerbated by COVID-19. We plan on requesting an extension so that we can adequately meet these goals. What opportunities for training and professional development has the project provided?This year, the project has trained 8 undergraduates, 12 graduate students and 8 postdoctoral research assistants, 13 scientists, 9 professional, 4 technical and 2 administrative staff members on various aspects of research and project management. The undergraduate students were exposed to experimental design and hands-on research experience while assisting graduate students and postdoctoral scientists with their projects. The graduate and post-docs were trained on standard operating procedures for greenhouse and growth chamber techniques, grass seedling identification, herbicide susceptibility/resistance, resistance screening methodology, molecular evaluations and screening, germination tests, procedure for extracting leachates from turf leaf clipping, and the evaluation of natural, non-synthetic products for control of annual bluegrass. The graduate students also acquired knowledge on data collection and analysis (seedling emergence, cumulative emergence curves), operating and recovering data from weather data loggers, compiling generated data and creating visuals, developing dynamic programming models for resistance management overseeding techniques, calibration and operation of small research plot equipment, among others. Research and technical staff were also trained on the fundamentals of herbicide mode-of-action, tissue culture techniques, new methods of seed harvesting and cleaning, as well as herbicide screening procedures. How have the results been disseminated to communities of interest?Project results have been disseminated to the broader clientele through various extension avenues and social media, including presentations, publications, peer review papers, webinars, social surveys, annual field days, society meetings, farm visits, trade journal articles, professional conferences, and posters. A site-of-action selection poster was disseminated by print to more than 2,000 stakeholders and by download to more than 1000 stakeholders, developed educational videos including videos designed for professional audiences with a basic understanding of turf management, produced podcasts, improved social media presence through twitter (Twitter handle @ ResistPoa) and ResistPoa.org website as a portal for stakeholders to interact and exchange knowledge. A webinar was conducted during early summer 2020, which was widely attended by the industry stakeholders. Few important links: https://twitter.com/Solutions4Turf/status/1228291548091121665?s=20 https://twitter.com/jbunruh/status/1272934869182472192?s=20 https://twitter.com/MakingtheTrnPod/status/1273496465265082368?s=20 http://resistpoa.org/ What do you plan to do during the next reporting period to accomplish the goals?The team will continue to complete additional surveys, set up new trials, continue screening remaining samples for herbicide resistance PRE/POST, conduct dose-response assays, complete TSR mechanism investigations and initiate NTSR studies, develop manuscripts based on research findings, continue to develop BMPs and deliver results to stakeholders. Future efforts will assess behavioral management changes due to our educational efforts, organize and compile data in a digital storage space and focus on the remaining objectives.

Impacts
What was accomplished under these goals? Objective 1a. Resistance surveys: This year, we collected a total of 1,450 annual bluegrass populations out of the proposed 2,000 populations suspected for herbicide resistance. These were collected across 5 hardiness zones and 4 turfgrass sectors including athletic fields, golf courses, sod production fields and lawn care. Surveys in the southern states (Zones 3, 4, and 5) are already complete. Some additional surveying will be conducted in northern locations (Zones 1 and 2) in late summer and fall 2020. All surveys are expected to conclude by December 31, 2020. Objective 1b. Resistance screening: POST herbicide evaluations with 10 different herbicides were conducted using tiller-propagated plants in greenhouse conditions. The survivors were advanced for further confirmation and target-site mutation analysis (objective 2a). PRE evaluations were already complete in several locations and is currently ongoing in other locations. Objective 1c. Planting seed contamination: We developed a protocol to test for annual bluegrass herbicide resistance using additional and unique PRE herbicides. We distributed one-page flyers to educate and encourage various growers and cleaners to submit populations. Last year, after Dr. Patton met with turf researchers, seed producers, seed cleaners, turfgrass breeders, and staff at a seed testing facility, we received approximately 60% of target plant populations. Screening of resistance will begin in the fall of 2020 from populations with sufficient seed. Objective 1d. Rapid diagnostic assays: Drs. Brosnan and McCarty's team have developed an agar-based assay to conduct dose-response experiments with indaziflam applied early-post emergence. The technique was able to illustrate pronounced differences in IC50 values among resistant populations and susceptible controls. So far, the following progress have been made: a) a candidate herbicide was identified for rapid diagnostic assay development, b) biotypes with known resistance to be used as standards in assay development were acquired, and c) populations from objective 1b were identified that were candidates for screening using the new assay. Objective 2a. Target-site resistance (TSR) and genetic relationships: We developed a semi-automated pipeline, which is cost efficient and accurate for the throughput analysis of a majority of the known target site mutations in Poa annua. This is a marked improvement over capillary sequencing.Our ampseq pipeline has proved especially useful for the detection of target site mutations in Poa.To date, we have developed PCR primers that target a total of 95 separate loci representing 23 total known target site mutations. In addition, we have sequenced loci for 193 populations and 231 TSR genes. Objective 2b. Non-target -site resistance (NTSR): We validated methodology and techniques for NTSR evaluation and currently waiting on dose-response to be completed on the selected populations. Objective 3a. Seedbank persistence: Poa seed were obtained from 10 different states, representing various climatic zones, tested for initial viability and germination, seed bags were prepared for burial in 7 different sites across the country at two different depths (surface and 5 cm). Objective 3b. Seedling emergence: Poa seedling emergence was monitored for the first year in 8 different states, spanning various agroclimatic zones. Results indicated bimodal seedling emergence especially in some southern states. Objective 3c. Phenology and adaptive traits: Poa seed were sourced from 10 states and were grown in a greenhouse in College Station to eliminate maternal environmental effect. Seed were harvested upon maturity and will be used in the common garden experiment. Objective 4a. Evaluation of non-chemical products and alternative compounds: A list of potential non-synthetic herbicides to be evaluated were developed and field tests were initiated during summer 2020. Objective 4b. Fraise mowing: Experiments were initiated at the University of Tennessee (Knoxville, TN) and the University of Florida (Jay, FL) to evaluate the efficacy of fraise mowing for controlling annual bluegrass in bermudagrass turf. Results showed that fraise mowing at 15- and 30-mm depth effectively reduced annual bluegrass populations compared to non-fraise mowed plots. Objective 4c. Grass species and variety selection: Soil leachate studies were conducted at the four participating states. Further, leaf extract trials were conducted to see if aqueous leaf extracts of selected turf grasses will affect germination, establishment and growth of Poa annua seed. Two runs were completed between March 20, 2020 and April 9, 2020 and the data is currently being analyzed. Poa seedling emergence suppression in various turfgrass trials began July 1, 2020. Seed germination tests are currently on-going. Objective 4d. Mowing regime and grass-clipping removal: To quantify and evaluate the influence of clipping collection after mowing on the return of viable seed of annual bluegrass to turfgrass stands, we collected Poa seed heads at various growing degree day timings across locations throughout winter and spring. We collected one year of data from most locations, but germination testing has been delayed due to COVID. We also modified the protocol for evaluating seed germination in the Petri dishes. Objective 4e. Irrigation and nutrient management: Experiments were conducted to evaluate the effects of irrigation frequency and mineral nutrient fertilization on annual bluegrass incidence in cool-season turfgrass. Results showed that phosphorus rates <50 kg P ha-1 reduced annual bluegrass incidence on seedbed or mature turfgrass. Preliminary results also indicate that less frequent irrigation decreases annual bluegrass incidence. Another set of experiments are being conducted at Rutgers and Oregon State to evaluate the effects of nitrogen fertilizer timing and rate on annual bluegrass incidence in Kentucky bluegrass and perennial ryegrass. Objective 5a, 5b. Socio-economic investigations: To identify major barriers that are impeding BMP adoption for integrated weed management by turf practitioners, we conducted focus group discussions, developed lists of growers and managers in the target turfgrass sectors, developed an online survey instrument for turfgrass managers in sports, golf and sod/seed production, turfgrass production industry, and implemented the surveyand analyzed survey data using univariate and multivariate methods. This specialized database will be used to assess if the project survey is capturing a representative sample of establishments and to assess the economic contribution of turfgrass activities in the project states. After pretesting the survey by stakeholders, it has been revised and launched in July 2020. Objective 6. Decision-support tool: A draft framework has been developed and the team is working on adding label information/data in spreadsheets. Objective 7. Outreach: This year of the project, we continue to add and update ResistPoa.org Website portal for stakeholders to interact with Extension and Educational material. The portal has 58 documents that can be sorted by turf type scenario (cool-season, warm-season, or transition zone), control method (biological, chemical, or cultural), and state (50 US states, international, or all. Our presence on the social media through the twitter handle @ ResistPoa continues to serve and attract 700 followers. In addition, we developed educational materials including videos designed for professional audiences with a basic understanding of turf management. Objective 8. Education: Materials for classroom education are being developed in collaboration with the Extension team.

Publications

  • Type: Other Status: Published Year Published: 2020 Citation: Carroll, D.E., Brosnan, J.T., McCullough, P.E., McCurdy, J.D., Patton, A.J., Castro, E.B., Liu, W. 2020. When is Poa annua seed most germinable in spring? Golf Course Management 88(2):79.
  • Type: Other Status: Published Year Published: 2020 Citation: Castro, E.B., McCurdy, J.D. 2020. Herbicide Classification Poster. Published online at www.resistpoa.org.
  • Type: Other Status: Published Year Published: 2019 Citation: Grubbs, B., J. McCurdy, and M. Bagavathiannan. Poa annua: A Plan of Action. GCM Magazine. October 2019. https://www.gcmonline.com/research/news/poa-annua-research
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Carroll, D., Brosnan, J.T., McCullough, P.E., McCurdy, J.D., Patton, A.J., Castro, E., Liu, W. 2019. When Is Poa Annua Seed Most Germinable during spring in the Transition Zone and Southern United States? In: Proceedings of the Crop Science Society of America Annual Meeting, San Antonio, TX.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Castro, E.B., McCurdy, J.D., Caputo, T.M., Brosnan, J.T., McCullough, P.E., Patton, A.J., Carroll, D.E. 2020. Effects of Temperature and Gibberellic Acid on the Germination of Poa annua Seeds in Maintained Turfgrass of Mississippi. In: Proceedings of the Southern Weed Science Society Annual Meeting, Biloxi, MS.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Grubbs, B., S.D. Askew, L.B. McCarty, M.T. Elmore, J.T. Brosnan, J.D. McCurdy, P.E. McCullough, B. Unruh, T.W. Gannon, A.J. Patton, J.E. Kaminski, A. Kowalewski, J.S. McElroy, and M. Bagavathiannan. 2019. Multi-State Survey and Preliminary Screening to Evaluate Herbicide Resistance Epidemic in Annual Bluegrass (Poa annua L.) in Managed Turfgrass Systems. In: Proceedings of the ASA-CSSA-SSSA Annual Meeting, San Anotonio, TX.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Hathcoat, D. B. Grubbs, S. Askew, L. McCarty, M. Elmore, J. Brosnan, J. McCurdy, B. Unruh, A. Patton, A. Kowalewski, J. Kaminski, J. S. McElroy, M. Bagavathiannan. 2020. A Multi-State Survey to Determine the Prevalence of Herbicide Resistance in Annual Bluegrass (Poa annua L.) in Managed Turfgrass Systems. In: Proceedings of the Southern Weed Science Society Annual Meeting, Biloxi, MS.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Osburn, A., Grubbs, B., Hathcoat, D., Askew, S., McCarty, L.B, Elmore, M.T., Brosnan, J., McCurdy, J.D., McCullough, P., Unruh, B., Gannon, T., Patton, A., Kaminski, J., Kowalewski, A., McElroy, J.S., Bagavathiannan, M.V. 2019. Multi-State Research Evaluating Seedling Emergence and Herbicide Resistance Epidemic in Annual Bluegrass (Poa annua L.) in Managed Turfgrass Systems. In: Proceedings of the ASA-CSSA-SSSA Annual Meeting, San Antonio, TX.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Osburn, A., M. Bagavathiannan, B. Grubbs. 2020. Multi-State Research Evaluating Seedling Emergence and Herbicide Resistance Epidemic in Annual Bluegrass (Poa annua L.) in Managed Turfgrass Systems. In: Proceedings of the Weed Science Society of America Annual Meeting, Maui, HI.
  • Type: Other Status: Published Year Published: 2020 Citation: McCurdy, J.D. 2020. The ResistPoa Project Enters a New Phase. Mississippi Turfgrass Magazine.https://theturfzone.com/mta/?ascat=73&sub=issue&issue_id=4425&rti=true&rel=1
  • Type: Other Status: Published Year Published: 2020 Citation: McCurdy, J.D. 2020. Research Update Concerning: Poa annua, Goosegrass, Path Rush, Native Areas, and Prophylactic Effects of Lexicon Fungicide on Bermudagrass Establishment. Simplot Spring Educational Meeting, Chattanooga, TN, March 11, 2020.


Progress 09/01/18 to 08/31/19

Outputs
Target Audience:Professional turfgrass and property managers, including golf course superintendents, lawn care operators, sports field managers, and seed/sod producers. The larger turfgrass and landscape industry is also a key stakeholder group, including industry suppliers, agrochemical distributors, consultants, industry advocates, and professional associations. Changes/Problems:Given that this is the first year of the project, we couldn't meet all survey targets during the Poa seed maturity window in 2019. Accordingly, our goal was revised to meet 50% of the sampling in 2019 and the rest in the 2020 field season. What opportunities for training and professional development has the project provided?During the past year, the project has trained 15 undergraduate students, 8 graduate students and 2 postdoctoral research assistants on various aspects. The undergraduate students were exposed to experimental design and hands-on research experience, in addition to receiving training on plant propagation and culturing. The graduate students and post-doctoral researchers have been directly involved in designing and conducting experiments, and mentored by the CO-PDs with critical thinking and problem solving skills. Moreover, the project provided professional development opportunities for 9 research staff and a project manager. The students and staff have been routinely attending monthly project update meetings where they have the opportunity to network and develop professional connections with other team members across the nation. The students and staff were also provided with opportunities to attend local and regional turf events to develop pertinent knowledge and enhance professional links. How have the results been disseminated to communities of interest?The results are currently being generated. During the reporting period, the team focused heavily on planning and initiating the nationwide herbicide resistance survey for Poa. However, some of the preliminary findings from this project are disseminated to the broader clientele through the project Twitter feed @ResistPoa. What do you plan to do during the next reporting period to accomplish the goals?The team will continue to complete the resistance surveys and screening, and will focus more on the remaining objectives.

Impacts
What was accomplished under these goals? During the reporting period, the project team has accomplished several tasks that support the overall goals of this project. Resistance surveys: A total of 854 of the proposed 2000 total populations have been collected as of June 2019 from Zones 2, 3, 4, and 5. Surveying is on-going in Zones 1 and 2, as temperatures remain cool enough for Poa annua growth and survival. Surveying in Zones 3, 4, and 5 has been concluded for the year and will continue in fall/winter of 2019 and spring of 2020. Our objective for the first year was to collect at least half (1000) of the total number of surveyed populations, which we are on-target to meet by September of 2019. Resistance screening: Herbicide susceptibility/resistance evaluations are at varying stages across the participating states. Mississippi has screened 136 populations for 8 post-emergence herbicides and 3 pre-emergence herbicides. Of these, 6% are suspected resistant to ALS inhibiting herbicides, 8% mitosis inhibiting herbicides, 15% photosystem II inhibiting herbicides, and 1% glyphosate resistant. Eleven populations are suspected resistant to multiple active ingredients. Virginia is conducting preliminary experiments on seed germination and culturing Poa in Conetainers using native soil. Other states dealing with higher temperatures (Texas and Florida) will initiate once greenhouse temperatures cool sufficiently in the fall, approximately late September 2019. Planting seed contamination: To determine planting seed contamination with resistant Poa, Dr. Patton traveled to Oregon in Nov 2018 to meet with crop production and turf researchers, seed producers, seed cleaners, turfgrass breeders, and staff at a seed testing facility. The purpose of the visit was to coordinate logistics related to the collection of plant material from a variety of sources for the project. Rapid diagnostic assays: Pilot experiments are being conducted by Drs. Brosnan and McCarty to develop rapid diagnostic methods for herbicide resistance. Progress has been made on identifying candidate compounds that could serve as biomarkers for susceptibility to indaziflam herbicide. Target-site resistance (TSR) and genetic relationships: The plants that were confirmed to be resistant to specific herbicide compounds based on the resistance assays are being shipped to Dr. McElroy at Auburn for target-site resistance mechanism analysis. Currently, primer sets are being developed to identify herbicide resistance snps. To create a set of herbicide resistant snp primers we began by searching literature for active sites and identifying pre-existing primer sets such as for the ALS gene. In our process, we have focused on creating homeolog specific multiplexable primers that span the herbicide resistant sites. New primers were designed from available Poa annua, Poa supine, and Poa infirma transcriptomes on NCBI. Annual bluegrass seedbank ecology: Seed sources have been identified and currently being received from participating states. The seed burial bags are being prepared for installing this multi-state experiment by early September. Required weather instrumentation have also been acquired by the participating scientists. Fraise mowing: Experiments have been initiated at the University of Tennessee (Knoxville, TN) and the University of Florida (Jay, FL) evaluating the efficacy of fraise mowing for control of annual bluegrass in bermudagrass turf. Research was conducted on common bermudagrass (Cynodon dactylon, cv. 'Vamont') in Tennessee and hybrid bermudagrass (C. dactylon x C. transvaalensis, cv. 'Tifway') in Florida. Installation of the treatment can be seen here: https://twitter.com/i/status/1139653592267120640. Grass species and variety selection: In addition to the leachate study, OSU is currently developing an additional protocol to evaluate allelopathy using four different plants: chewings fescue, annual bluegrass and lettuce. For this protocol we will be using an agar medium with a mesh semi-permeable layer to segregate plants. These trials were just initiated at Oregon State University. Mowing regime and grass-clipping removal: Field experiments were initiated in January 2019 in Georgia, Mississippi, Tennessee, and Indiana, to evaluate seed viability of annual bluegrass at various timings throughout winter and spring. Seed germination and viability tests are currently being conducted. Most locations are currently running the seed analysis in growth chambers and we hope to have the initial results from all locations by October. Irrigation and nutrient management: Oregon State initiated a greenhouse experiment to evaluate the effects of varying phosphorus rates on the establishment competition of perennial ryegrass (?Lolium perenne?) and annual bluegrass (?Poa annua?). Annual bluegrass and perennial ryegrass were seeded to pots filled with USGA sand (10.7 ppm phosphorus) amended with 0, 25, 50, 99 or 197 kg phosphorus per hectare. Results are being evaluated to determine the influence of phosphorus on annual bluegrass and perennial ryegrass germination and percent cover. Several allied experiments were also initiated recently. Socio-economic investigations: The proposed FG structure and protocol was approved by the Portland State University Institutional Review Board (IRB) for research on human subjects in December 2018. The first FG (7 participants) was conducted at the Sports Turf Managers Association meetings in Phoenix, AZ on January 25, 2019. The second FG (8 participants) was conducted at the Golf Industry Show in San Diego on February 7, 2019. The third FG (11 participants) was conducted at the Turf Producers International in Charlotte, NC on February 19, 2019. The fourth FG (8 participants) was conducted in White Plains NY on March 19, 2019 to hear turf sector participants from northeastern states as there was low representation from this region in the previous focus groups. The four FG discussions held to date have been transcribed to prepare for qualitative analysis. The focus groups were successful in engaging all participants to deliver their individual perspectives on the five above categories of information sought. Economic analysis: Work to date has focused on collecting cost of operation data for golf (and other turf) facilities. Data have been obtained from published course records and cooperative extension resources. Where possible, separate data for weed control compounds used and weed control costs have been collected. An economic model is also being developed. Based on results from initial focus group exercises, we have begun developing alternative behavioral models. Decision-support tool: A wire-frame is being developed to establish a structure for the decision support tool. Further development will continue once more research data is available in 2020. Outreach: During year 1 of the project, our efforts have led to the development of the ResistPoa.org website, which serves as a portal for stakeholders to interact with Extension and Educational materials. The ResistPoa website includes introductory lessons for stakeholders. Further, a three module, educational presentation was also developed surrounding herbicide resistance management in annual bluegrass. The site also hosts a unique Literature Search feature for relevant information concerning Poa annua resistance and management. A presence on social media has been established through the Twitter handle @ResistPoa, where we have a following of over 500.

Publications

  • Type: Other Status: Published Year Published: 2019 Citation: McCurdy, J.D. Module 1. Introducing Poa annua. April 16, 2019. http://resistpoa.org/tools/slide-sets/poa-annua/
  • Type: Other Status: Published Year Published: 2019 Citation: McCurdy, J.D. Module 2. Fundamentals of Herbicide Resistance. April 16, 2019. http://resistpoa.org/tools/slide-sets/herbicide-mode-of-action/
  • Type: Other Status: Published Year Published: 2019 Citation: McCurdy, J.D. Module 3. Herbicide Sites of Action. April 16, 2019. http://resistpoa.org/tools/slide-sets/best-management-practices/