Influence of Cultural and Chemical Management Practices on Dollar Spot Severity and Sclerotinia homoeocarpa Sensitivity to Fungicides.

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2 Influence of Cultural and Chemical Management Practices on Dollar Spot Severity and Sclerotinia homoeocarpa Sensitivity to Fungicides. A.I. Putman, Graduate Research Assistant and J.E. Kaminski, Assistant Professor of Turfgrass Pathology Department of Plant Science University of Connecticut, Storrs, CT 1376 Storrs Road, Unit 4067 Storrs, CT ABSTRACT Dollar spot (Sclerotinia homoeocarpa) is probably the most significant disease of coolseason turf in the United States north of the transition zone. In New England, dollar spot generally appears in late spring or early summer and ceases activity in late autumn. Although the disease is typically most destructive during the early summer and autumn months, S. homoeocarpa may be active throughout the entire year. Golf course fairways are particular areas of concern for dollar spot management because they represent large acreages of highly susceptible turfgrasses such as annual bluegrass (Poa annua) and/or creeping bentgrass (Agrostis stolonifera). While dollar spot may be managed by a combination of cultural and chemical management practices, anecdotal reports have described increases in dollar spot severity and therefore reduction in acceptable control. This increased difficulty in managing dollar spot may be caused by several factors, including changes in cultural practices, poor fungicide application methods, and possibly S. homoeocarpa resistance to select fungicides. The application of fungicides well in advance of the expected appearance of symptoms, or dormant applications, has received considerable research attention. Studies conducted in 2006 and 2007 at Stanley Golf Course in New Britain, CT, have noted appreciable reductions in dollar spot incidence from dormant fungicide applications. While it is surmised these earlyseason applications suppress the accumulation of S. homoeocarpa inoculum, the level of control University of Connecticut 1 Kaminski and Putman

3 afforded by dormant applications with respect to more traditional preventive chemical timings is largely unknown. No information is available on the influence of application methods on the efficacy of early-season fungicide applications. Data collected in 2007 suggest that these methods may influence fungicide performance. Chemical management of dollar spot is generally most effective when fungicides are applied at regular intervals to ensure adequate protection of susceptible, continually growing leaf tissue from S. homoeocarpa. However, several cultural practices may influence the rate at which new, unprotected leaf tissue is produced. Plant growth regulators (PGRs) are commonly used on golf courses to reduce maintenance and improve turf quality by limiting vertical shoot growth. While golf course fairways are typically mown three times week -1, demands for superior playing conditions have induced some turf managers to mow fairways 6 or more times week -1. Research-based data on the interaction of PGRs and mowing frequency on dollar spot control is limited, and the ability of a combination of these factors to reduce the amount of fungicide needed to manage dollar spot over a season is unknown. In addition to the above factors, losses in fungicide efficacy are commonly attributed to fungicide resistance. Thus, the scope and level of S. homoeocarpa insensitivity to fungicides in New England is being assessed. Over 1,500 isolates of S. homoeocarpa were collected in 2006 and 2007 from golf courses in New England and New York. The sensitivity of these isolates to iprodione, propiconazole, and thiophanate-methyl will be assayed in early University of Connecticut 2 Kaminski and Putman

4 I. INFLUENCE OF EARLY-SEASON FUNGICIDE APPLICATIONS ON THE REDUCTION OF SCLEROTINIA HOMOEOCARPA INOCULUM. Introduction Recent studies and anecdotal reports by turfgrass managers have reported extended periods of dollar spot (Sclerotinia homoeocarpa) control from fungicides applied at nontraditional timings. These dormant applications, made prior to the appearance of disease symptoms but while the pathogen may be actively growing, may reduce dollar spot severity early in the disease epidemic. Little published research, however, has examined the optimal timing of dormant applications or whether these applications provide control comparable to a traditional preventive application. In addition to these factors, no information is available on the influence of spray droplet size or post-application irrigation on the efficacy of dormant fungicide applications. This information is important as targeting the pathogen at its overwintering site may play an important role in fungicide efficacy when applied to asymptomatic turf. The objectives of this study were to evaluate the impact of droplet size and post-application irrigation on dollar spot control with dormant fungicide applications made in the late autumn or early spring, when compared to traditional preventive timings made immediately prior to the appearance of symptoms. Materials and Methods This field study was initiated in 2007 on a mixed stand of creeping bentgrass and annual bluegrass (Poa annua L.) at Stanley Golf Course located in New Britain, CT. Turf was maintained to a height of 0.5 in. and mown approximately three times week -1. The site was irrigated as needed to prevent drought stress. Plots measured 3 ft x 6 ft and were University of Connecticut 3 Kaminski and Putman

5 arranged in a randomized complete block with three replications. Treatments were constructed in a 4 (fungicide) x 4 (application timing) x 2 (nozzle) x 2 (post-application irrigation) factorial as follows. Fungicide treatments were Emerald (70WG; boscalid) at 0.18 oz ft -2, Bayleton (50WG; triadimefon) at 1.0 oz 1000 ft -2, Curalan (50EG; vinclozolin) at 1.0 fl oz 1000 ft -2, and a tank mix of Daconil Ultrex (82.5WDG; chlorothalonil) at 3.2 oz 1000 ft -2 + Banner MAXX (1.3ME; propiconazole) at 1.0 fl oz 1000 ft -2. Fungicides were applied on 18 (A) or 24 (B) October 2006, 24 April (C) or 23 May (D) Treatments were applied using a CO 2 pressurized (40 psi) backpack sprayer equipped with a singlenozzle wand and calibrated to deliver 1 gal water 1000 ft -2. Treatments were applied using an extended range (XR8004E) or air induction (AI9504E) even flat-fan nozzles. Postapplication irrigation was simulated by applying approximately 0.1 in water to individual plots immediately (< 5 min) following fungicide application. All other treatments were allowed to dry on the surface and were not irrigated for 24 hours. During the early phase of disease activity, disease incidence was assessed by visually counting the number of dollar spot infection centers plot -1. As dollar spot symptoms became more severe, percent plot area blighted by S. homoeocarpa was visually estimated on a linear 0 to 100 scale, where 0 = no dollar spot symptoms present and 100 = entire plot area affected by S. homoeocarpa. The area under the disease progress curve (AUDPC) was determined for both ratings. Data were subjected to a one-way analysis of variance, and means were separated using Tukey s significant difference test. Infection center [(x i + 1) 1/4 ] and plot area blighted [log 10 (x i + 0.1)] data were transformed prior to analysis. University of Connecticut 4 Kaminski and Putman

6 Results Little active dollar spot was observed between the initiation of treatments on 18 October and the third application on 24 April. Dollar spot became active in late May prior to the final treatment date. In late May, dollar spot pressure was low to moderate, with 3.5% untreated control plots affected by S. homoeocarpa. Dollar spot became moderate to severe in June, precluding the assessment of the number of infection centers after 13 June. Thus, the total disease for infection center data (IC AUDPC) represents the early stage of the epidemic from the final application to three weeks hence. Dollar spot incidence peaked on 20 June, with 24.3% plot area blighted by S. homoeocarpa in untreated control plots. Thereafter, dollar spot pressure declined to moderate levels (13.5 to 19.7%) in untreated plots. Application date. On rating dates in late May, dollar spot was low ( 1.3%) in plots treated on 24 April, while dollar spot was low to moderate (0.3 to 4.0%) for applications at the autumn timings (A and B). Although plots treated with Daconil Ultrex + Banner MAXX at timings A or B exhibited low levels of dollar spot (0.3 to 1.1%) in late May, disease incidence in plots treated with Bayleton, Curalan, or Emerald was generally higher and more variable. At the peak of disease severity (24.3%) on 20 June, percent dollar spot in plots treated at timing D (23 May) ranged from 2.8 to 15.5%, although most treatments exhibited < 10% PAB. Dollar spot incidence was also less for timings A (5.7 to 23.3%) and C (2.0 to 18.0%), when compared to the untreated control. Total disease over the entire study (AUDPC) was generally similar between treatments applied in the spring (C and D), and both were lower when compared to the untreated control. Although total disease (AUDPC) University of Connecticut 5 Kaminski and Putman

7 was generally lower for treatments applied at timing A (18 Oct) when compared to the untreated, AUDPC values were generally higher when compared to C or D. Except for Daconil Ultrex + Banner MAXX (all nozzle and water-in combinations), few reductions in AUDPC were noted for timing B (24 Oct) when compared to all other timings or the untreated control. Nozzle and post-application irrigation. The AUDPC data revealed that except for application timing D, Daconil Ultrex + Banner MAXX applied with the XR nozzle resulted in less total disease when compared to the AI nozzle, regardless of post application irrigation. Few other differences between nozzle treatments were noted when considered alone. A consistent trend, however, was observed for post-application irrigation when averaged over all treatments. When treatments were applied in 2006 (A or B), postapplication irrigation generally reduced dollar spot control when compared to treatments not subjected to irrigation. The aforementioned trend was also observed for some treatments applied at timing C. Contrary to most fungicides evaluated in this study, post-application irrigation had the opposite effect on Emerald applied in the spring (C or D). Emerald treatments receiving post-application irrigation generally resulted in less dollar spot when compared to allowing the fungicide to dry. While the nozzle and post-application irrigation factors considered alone caused consistent trends for treatments applied at timings A, B, or C, an unexpected interaction between these factors was observed for treatments applied at the traditional preventive timing D (23 May). Except for Emerald, watering-in fungicides applied with the AI nozzle increased total disease when compared to allowing the fungicide to dry, whereas postapplication irrigation enhanced the efficacy of fungicides applied with the XR nozzle. University of Connecticut 6 Kaminski and Putman

8 Discussion Disease incidence was highly variable throughout the study area at Stanley, and few significant differences were observed among treatments. However, several non-significant but consistent trends were observed. Treatments applied on 18 October 2006 or 24 April 2007 reduced dollar spot when compared to the untreated control. While these reductions were noted under periods of high disease pressure in late June and persisted until the final rating date (4 July), no treatment provided a level of control that was considered acceptable ( 0.5%) by this time. Fungicides applied 18 October 2006 or 24 April 2007 resulted in dollar spot levels comparable to those applied at the traditional preventive timing (23 May 2007). Treatments applied on 24 October 2006 generally did not provide appreciable reductions in dollar spot when compared to the untreated control. More research is needed to determine if dormant fungicide applications can impact the total amount of fungicide needed for dollar spot control over the entire season. For all dormant treatments, selecting the XR nozzle reduced dollar spot when compared to the AI nozzle for Daconil Ultrex + Banner MAXX only. Watering-in fungicides on all three dormant applications generally resulted in reduced dollar spot control when compared to treatments in which fungicides were allowed to dry. The control afforded by Emerald applied at the late spring or preventive timing, however, was improved by postapplication irrigation, regardless of nozzle selection. Except for Emerald, post-application irrigation resulted in an increase in dollar spot when fungicides were applied with the AI nozzle but enhanced the efficacy of those applied with the XR nozzle when treatments were applied at the traditional preventive dollar spot timing (e.g., 23 May). University of Connecticut 7 Kaminski and Putman

9 Future Research Results of this work indicate that all factors examined in this study (droplet size, application timing, post-application irrigation and fungicide) play an important role in dollar spot control. When applied during periods favorable for S. homoeocarpa overwintering, it appears that post-application irrigation for treatments applied using a fine droplet producing nozzle improved the movement of the fungicide to the organism. On the other hand, when fungicides were applied using a nozzle that produced a very coarse droplet, post-application irrigation may have moved the chemical past the overwintering location and therefore reduced suppression of S. homoeocarpa. The data will be further analyzed using pre-planned contrasts to clarify the non-significant trends observed in the present summary. This study will be repeated at multiple sites Due to the apparent inconsistent influence of dormant applications made in the late autumn, only spring application timings will be utilized. University of Connecticut 8 Kaminski and Putman

10 II. INTERACTION AMONG PLANT GROWTH REGULATORS, FUNGICIDES, AND MOWING FREQUENCY ON SEASONAL CONTROL OF DOLLAR SPOT. Introduction Demands for superior playing conditions on golf course fairways have led to the widespread use of plant grown regulators (PGRs) and increasing interest among managers of more frequent mowing to enhance turf quality, playability, and aesthetics. These practices are generally performed from late spring to autumn, a period when dollar spot (Sclerotinia homoeocarpa) is most severe. While numerous research studies have evaluated the influence of PGRs on dollar spot control for a limited time frame alone or in combination with fungicides, no information is available on the ability of regular PGR use on the amount of fungicide needed to manage dollar spot over an entire season. Mowing frequency has been studied for its influence on dollar spot as it relates to dew removal, but the effect of mowing frequency solely on the residual efficacy of fungicides remains unknown. The objectives of this research are to elucidate the interactions between mowing frequency and PGRs on dollar spot severity and to determine their influence on total fungicide applications needed to manage dollar spot over the entire season. Materials and Methods This field study was initiated in 2007 at the University of Connecticut Plant Science Research and Education Facility in Storrs, CT. In October 2005, Putter creeping bentgrass was seeded at a rate of 1.0 lb 1000 ft -2. In September 2006, the study area was inoculated with sterile Kentucky bluegrass (Poa pratensis L.) seeds infested with S. homoeocarpa. University of Connecticut 9 Kaminski and Putman

11 Plots measured 3ft x 6 ft, and were arranged in a randomized complete block with four replications. The study was designed as a 3 (mowing frequency) x 3 (PGR) x 5 (fungicide) factorial. Mowing treatments consisted of turf mown two, four, or six days per week to a height of 0.5 in. To prevent the confounding effects of fungicide clipping residues on adjacent plots, clippings were removed. Plant growth regulators were applied on approximately a 21-day interval, and included Primo MAXX (1EC; trinexapac-ethyl) at 11 fl oz A -1, Trimmit (2SC; paclobutrazol) at 16 fl oz A -1, and a non-treated control. Four fungicides were selected based on varying modes of activity within the plant. Fungicide treatments included Emerald (70WG; boscalid) at 0.13 oz 1000 ft -2, Daconil Ultrex (82.5WDG; chlorothalonil) at 1.8 oz 1000 ft -2, Chipco (26GT; iprodione) at 2.0 fl oz 1000 ft - 2, Banner MAXX (1.3EC; propiconazole) at 1.0 fl oz 1000 ft -2, and a non-treated control. Initial PGR and fungicide treatments were applied on 1 June when active dollar spot symptoms were observed. Based on previous findings that reductions in leaf wetness duration reduce disease symptoms, dew was removed seven days per week between 700 and 900 hours for the duration of the study (1 June to 28 Sept). Dollar spot incidence was assessed daily in all fungicide-treated plots by counting the number of dollar spot infection centers plot -1. Individual fungicide treatments were reapplied only when dollar spot levels reached a commercially unacceptable threshold ( 5 spots per plot). All fungicide and PGR treatments were applied with a CO 2 pressurized (40 psi) backpack sprayer equipped with a single nozzle wand and calibrated to deliver 1.0 gal water 1000 ft -2. All treatments were applied using a flat fan air induction nozzle (AI9504E), which had previously been shown to provide adequate suppression of dollar spot (Kaminski, 2005). University of Connecticut 10 Kaminski and Putman

12 Data collection. Dollar spot severity was assessed visually by estimating the percent plot area affected by S. homoeocarpa on a linear 0 to 100 percent scale, where 0 = entire plot area devoid of dollar spot and 100 = entire plot area affected by S. homoeocarpa. Creeping bentgrass quality was assessed visually on a linear 0 to 10 scale, where 0 = entire plot area brown or dead, 7 = minimally acceptable quality for a golf course fairway, and 10 = optimal color and density. Quality was also assessed objectively using the normalized difference vegetation index (NDVI). Five index readings plot -1 were taken using the Spectrum TCM500 hand-held light reflectance meter (Spectrum Technologies, Inc., Plainfield, IL). To determine the influence of PGRs on suppressing creeping bentgrass growth, clippings were collected weekly from each plot, dried in a hot water-driven dessicating oven, and weighed to obtain the clipping yield dry weight. Statistical analysis. Data collected throughout the study will be assessed to determine if any transformations are necessary prior to statistical analyses. Data obtained weekly will be subjected to analysis of variance, and treatment means will be compared using preplanned orthogonal contrasts in PROC MIXED in SAS v The area under the disease progress curve (AUDPC) will be determined for the development of disease symptoms over the course of the study. Results and Discussion Statistical analyses of fungicide application data is pending, but are trends are summarized below and raw data shown in Tables 1 and 2. For several fungicide and PGR combinations (Banner + Primo, Chipco alone, Chipco + Trimmit, Daconil alone, and Emerald + Primo), plots mown twice week -1 were retreated less frequently on average when University of Connecticut 11 Kaminski and Putman

13 compared to plots mown six times week -1. When PGRs were considered for each fungicide and mowing frequency combination, differences between plots treated with Primo and no PGR were minimal. As expected, plots treated with Trimmit resulted in a major reduction in the total number of fungicide applications necessary to suppress dollar spot when compared to Primo or no PGR. The impact of mowing frequency appeared to have less of an impact when compared to the main effect of fungicide and PGR. Further Research Data from 2007 will be further analyzed and summarized. This study will be repeated in 2008 at the University of Connecticut Plant Science Research and Education Facility. University of Connecticut 12 Kaminski and Putman

14 Table 1. Summary of the influence of mowing frequency on early curative management of dollar spot with various fungicides under various PGR programs. Fungicide PGR Mowing Frequency No. fungicide apps Mean days between apps. # Banner MAXX none 2x x x Primo 2x x x Trimmit 2x x x Chipco 26 GT none 2x x x Primo 2x x x Trimmit 2x x x Daconil Ultrex none 2x x x Primo 2x x x Trimmit 2x x x Emerald none 2x x x Primo 2x x x Trimmit 2x x x Fungicides treatments were Banner MAXX (1.0 fl. oz ft. -2 ), Chipco 26 GT (2.0 fl. oz ft. -2 ), Daconil Ultrex (1.8 oz 1000 ft. -2 ), and Emerald (0.13 oz 1000 ft. -2 ). The fungicide non-treated is omitted from this summary. Plant growth regulator treatments were Primo MAXX (11 fl. oz. A -1 ), Trimmit (16 fl. oz. A -1 ), and a non-treated control. Plots were mown individual with a walk-behind greens mower. The number of fungicide applications made based on a retreatment threshold of a mean > 5 infection centers for a treatment. # The mean length of time in days required until a treatment exceeded the reapplication threshold. University of Connecticut 13 Kaminski and Putman

15 Table 2. Summary of the influence of PGRs on early curative management of dollar spot with various fungicides under various mowing frequency regimes. Fungicide Mowing Frequency PGR No. fungicide apps Banner MAXX 2x none Primo Trimmit x none Primo Trimmit x none Primo Trimmit Chipco 26 GT 2x none Primo Trimmit x none Primo Trimmit x none Primo Trimmit Daconil Ultrex 2x none Primo Trimmit x none Primo Trimmit x none Primo Trimmit Emerald 2x none Primo Trimmit x none Primo Trimmit x none Primo Trimmit # Mean days between apps. # Fungicides treatments were Banner MAXX (1.0 fl. oz ft. -2 ), Chipco 26 GT (2.0 fl. oz ft. -2 ), Daconil Ultrex (1.8 oz 1000 ft. -2 ), and Emerald (0.13 oz 1000 ft. -2 ). The fungicide non-treated is omitted from this summary. Plant growth regulator treatments were Primo MAXX (11 fl. oz. A -1 ), Trimmit (16 fl. oz. A -1 ), and a non-treated control. Plots were mown individual with a walk-behind greens mower. The number of fungicide applications made based on a retreatment threshold of a mean > 5 infection centers for a treatment. The mean length of time in days required until a treatment exceeded the reapplication threshold. University of Connecticut 14 Kaminski and Putman

16 III. GEOGRAPHIC DISTRIBUTION OF FUNGICIDE-INSENSITIVE SCLEROTINIA HOMOEOCARPA ISOLATES FROM TURF UNDER VARIOUS MANAGEMENT REGIMES ON GOLF COURSES IN NEW ENGLAND. Introduction Fungicides are generally applied at regular intervals to preventively manage dollar spot (Sclerotinia homoeocarpa) on golf courses. However, the repeated use of fungicides may induce the selection of strains of the pathogen with reduced sensitivity to compounds and cause disease control losses. Fungicides in the benzimidazole, dicarboximide, and demethylation-inhibiting classes are commonly used for dollar spot management. While strains of S. homoeocarpa insensitive to these fungicides have been identified in the United States, the scope of this phenomenon in New England remains unknown. Additionally, little information exists on the influence of different fungicide regimes on resistance development. The prevalence of insensitive S. homoeocarpa populations must be ascertained to determine if resistance management practices are warranted, or if anecdotal reports of control losses may be attributed to other factors. The objective of this research is to assay the level of sensitivity to iprodione, propiconazole, and thiophanate-methyl of S. homoeocarpa isolated from turf under various management regimes on golf courses throughout New England. Materials and Methods Isolate Collection. Dollar spot samples were collected via site-visits or from samples received at the University of Connecticut Turfgrass Disease Diagnostic Center. Individual isolates of S. homoeocarpa were cultured on selective media and purified. In addition, intensive sampling (> 60 samples) was conducted at several sites in southern New England. University of Connecticut 15 Kaminski and Putman

17 In all cases, the pathogen was identified by visual comparison of mature mycelial colonies to known, representative samples. In vitro Sensitivity. The sensitivity of S. homoeocarpa obtained from the baseline population at the Vineyard Golf Club in Edgartown, MA to iprodione, propiconazole, and thiophanate-methyl will be estimated to serve as a basis of comparison for other isolates. Relative growth (RG) will be calculated as the mean of replicates at each of four serial concentrations for iprodione and propiconazole. The RG of each isolate will be plotted against log 10 of fungicide concentration and the fungicide concentration causing 50% RG (EC 50 ) will be estimated by linear regression. The sensitivity of S. homoeocarpa to the three aforementioned fungicides from populations throughout New England will be surveyed. Isolates were collected from turf under various management regimes (putting green, fairway, tee, rough) at each golf course. A quantitative procedure, using growth at a single discriminatory fungicide concentration as determined by regression, has been utilized to determine sensitivities for S. homoeocarpa. Isolates collected will be grown on PDA amended with the discriminatory concentration, and the concentration causing an estimated 50% growth inhibition (EC 50(D) ) will be determined by applying RG at the single concentration to the aforementioned regression equation. The aforementioned analysis will be performed on baseline isolates for iprodione and propiconazole, because sensitivity of S. homoeocarpa to iprodione and propiconazole is quantitative, giving a range of sensitivity values. However, due to the qualitative nature of thiophanate-methyl sensitivity, isolates will be grown on PDA amended with 1,000 µg a.i. ml -1 of the fungicide and poured on smaller (60 x 15 mm) plastic Petri plates (Jo et al., 2006). University of Connecticut 16 Kaminski and Putman

18 Results To Date During 2006 and 2007, a total of 408 individual S. homoeocarpa isolates from 205 locations were obtained via site visits to or samples received from golf courses in New England and New York (Tables 3). In addition, intensive sampling of 18 select sites in southern New England yielded 1,104 isolates of the pathogen (Tables 4). These isolates are currently in storage at the University of Connecticut Turfgrass Disease Diagnostic Center. University of Connecticut 17 Kaminski and Putman

19 Table 3. Number of courses and S. homoeocarpa isolates obtained in this study by state for individual samples. State No. of Courses No. of Isolates Connecticut Maine Massachusetts New Hampshire 8 12 New York 9 13 Rhode Island Vermont 5 7 Total University of Connecticut 18 Kaminski and Putman

20 Table 4. Origin of S. homoeocarpa isolates obtained through intensive sampling. No. No. Course Location State Turf Hosts Samples Isolates Black Hall Club, The Old Lyme CT Fairway Agrostis stolonifera L Chemawa Country Club North Attleboro MA Fairway Poa annua L., Lolium perenne L., or Poa pratensis L Country Club of Fairfield Fairfield CT Fairway A. stolonifera, P. annua, or L. perenne Country Club of Farmington Farmington CT Fairway A. stolonifera Country Club of New Canaan New Canaan CT Tee A. stolonifera or P. annua Hunter Golf Club Meriden CT Fairway A. stolonifera Hunter Golf Club Meriden CT Green A. stolonifera or P. annua Lake of Isles Golf Club Ledyard CT Fairway A. stolonifera Oak Hills Park Golf Course Norwalk CT Fairway A. stolonifera Oak Lane Country Club Woodbridge CT Fairway A. stolonifera or P. annua Pine Oaks Golf Club South Easton MA Green A. stolonifera Shennecossett Golf Course Groton CT Green A. stolonifera Stanley Golf Course New Britain CT Fairway A. stolonifera TPC of Boston Norton MA Fairway A. stolonifera TPC of Boston Norton MA Tee A. stolonifera TPC of Boston Norton MA Rough P. pratensis Vineyard Golf Club Edgartown MA Green A. stolonifera Warwick Country Club Warwick RI Fairway A. stolonifera, P. annua, or L. perenne Wee Burn Country Club Darien CT Fairway A. stolonifera Winnapaug Country Club Westerly RI Green A. stolonifera or P. annua Winnapaug Country Club Westerly RI Fairway P. pratensis, A. stolonifera, P. annua, or L. perenne Wintonbury Hills Golf Course Bloomfield CT Fairway A. stolonifera Total

21 Further Research The sensitivity of the stored isolates will be determined in early In addition, the fungicide use history of sampled courses will be obtained through a follow-up survey. Acknowledgements The project was made possible through funding provided by The New England Regional Turfgrass Foundation, Syngenta Professional Products, The University of Connecticut Research Fund, The United States Golf Association, and the UConn Turfgrass Disease Diagnostic Center. We thank all superintendents that provided isolates for this study. We also thank Mr. John Napier and Stanley Golf Club for providing space for research trials. Special thanks also are given to Drs. Geunhwa Jung and Young-Ki Jo for instruction and helpful comments. University of Connecticut 20 Kaminski and Putman