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TURFGRASS SCIENCE

Establishment of Poa annua var. reptans from Seed under Golf Course Conditions in the Pacific Northwest

^a Washington State Univ. Puyallup Research and Extension Center, 7612 Pioneer Way East, Puyallup, WA 98371
^b Dep. of Crop and Soil Sciences, Washington State Univ., Pullman, WA 99163

^* Corresponding author (miltner{at}puyallup.wsu.edu)

	ABSTRACT

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
The recent release of ‘True-Putt’ (previously ‘DW-184’) creeping bluegrass [Poa annua f. reptans (Hausskn.) T. Koyama] gives turfgrass managers a new option for seeding annual bluegrass (P. annua L.) greens. Because little is known about the culture and management of this new cultivar, experiments were conducted to determine effective seeding practices under sunny and shady conditions. Sites included sand-based media in full sun, sand-based media in partial shade, and fine sandy loam soil in full sun. Three surface mulch treatments (peat moss, pelletized paper mulch, and polypropylene fabric) and an unmulched control were compared. Peat resulted in the most rapid seedling emergence, percentage cover, and vertical growth rate, followed closely by the polypropylene fabric. Pelletized mulch had limited effectiveness. Because introducing an organic layer such as peat onto the surface of sand-based greens can alter soil physical properties, the fabric may be the best choice. Seedling emergence occurred more quickly in the sun than the shade, but there was no difference in rate of coverage due to sun exposure. Establishment occurred quickly on the sandy loam soil even in unmulched plots, indicating that use of a mulch was less important there than on the sand-based media. Results of this research will help turfgrass practitioners to effectively establish this newly commercially available species, especially in settings where rapid turf establishment is important.

Abbreviations: DOP, date of planting • WAP, weeks after planting

	INTRODUCTION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
ANNUAL BLUEGRASS is often found in turfgrass mixtures on golf course putting greens, and other areas throughout the northern USA. Individual plants exhibit growth habits on a continuum from a true winter annual to a perennial (Beard, 1999). It is often regarded as an undesirable species because of its reputed lack of stress tolerance, light yellow-green color, and prolific flowering in the spring, which can create an uneven putting surface (Beard, 1973). Until the late 1990s, annual bluegrass seed was not available commercially, and its existence in maintained turfgrass areas was due to natural colonization, sometimes promoted by cultural management. Through this colonization, annual bluegrass can become the dominant species with time (Beard et al., 1978), forcing a golf course superintendent to manage this grass as the desired species, as opposed to treating it like a weed.

Recent plant improvement efforts with perennial biotypes of annual bluegrass (P. annua var. reptans) have concentrated on selecting plants that demonstrate low growth habit, high shoot density, fine leaf texture, acceptable color, and reduced seed head formation. The first commercially available cultivar was DW-184 (White and Carson, 1999), renamed True-Putt and marketed with the common name of creeping bluegrass. It has been described as a stoloniferous variety with fewer seed heads than many wild types, greater adventitious rooting and herbicide tolerance, and more shade tolerance than creeping bentgrass (Beard, 1999). Before the release of True-Putt, there were three options for establishing annual bluegrass: collect clippings during periods of seed head production and distribute them with the hope that mature seed will germinate; establish from cores collected during aerification; or plant seed of creeping bentgrass (Agrostis stolonifera L.) or another species and wait for annual bluegrass to encroach and dominate. If loss of existing annual bluegrass occurs due to pest injury, environmental stress, or vandalism, seeding of creeping bluegrass may be a better alternative than these previous options. In addition, seeding True-Putt should result in a more uniform stand than the visually variable stands that exist from encroachment of indigenous annual bluegrass.

The improved traits of True-Putt creeping bluegrass suggest that it may be a suitable turfgrass for putting greens, tees, or other golf course turf. However, the lack of published research on management of this species suggests the need to evaluate its growth and culture. For golf course use, two important factors in the success of a grass are rate of establishment and adaptability to different environmental conditions. The need to generate revenue through play makes it desirable for turf to establish quickly, and post-seeding mulches can promote this. Mulches can help to create a favorable microenvironment for germination, hypocotyl emergence, and juvenile plant development (Beard, 1973). Barkley et al. (1960) found that materials that provided optimized temperature-moisture relationships were the most beneficial during germination of Kentucky bluegrass. When establishing turfgrass on sand-based media for putting greens, tees, or sports fields, persistent moisture at the surface is often crucial because of the limited water holding capacity of coarse-textured soils. Brauen (1988) found that increasing the peat moss to sand ratio of topdressing during bentgrass seedling establishment on sand resulted in higher soil moisture, more rapid germination, and higher percentage cover.

Organic materials such as sawdust, straw, wood chips, and other materials have been used as mulches (Turgeon, 1996). Difficulty in handling, high C to N ratios, and potential for weed seed introduction makes these materials less than ideal. Because of the low mowing heights on greens, mulches that decompose quickly requiring minimal clean up after turf establishment are desirable. Materials made of wood fiber cellulose and geotextile spun fabrics have gained popularity in recent years (Vavrek, 1999) because they can be easily removed following seedling germination. Removing the mulch helps maintain surface smoothness and also eliminates the potential for a surface organic layer to disrupt soil physical properties (Beard, 1973).

Environmental exposure can also impact turf establishment. Greens and tees are often built in shaded areas, and tree shade can inhibit seed germination (Bell et al., 2000; Toole and Borthwick, 1971; Toole and Koch, 1977). Reduced light intensity can also result in physiological and morphological changes that adversely affect growth once seeds germinate (Dudeck and Peacock, 1992). The objective of this research was to evaluate establishment of True-Putt creeping bluegrass for its use on golf course greens, tees, and similar areas. The use of postseeding surface mulches was evaluated under full sun and shade, and in sand-based media and a fine sandy loam soil, to identify conditions that promote rapid and uniform establishment.

	MATERIALS AND METHODS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
A field experiment to evaluate establishment of True-Putt creeping bluegrass from seed was repeated seven times between May 1999 and November 2000. The study was conducted at the WSU Puyallup Farm 5 Turfgrass Research Facility (47°N lat., 122°W long.), located approximately 60 km southeast of Seattle, WA. One repetition of the experiment was conducted on a Puyallup fine sandy loam (coarse loamy over sandy or sandy-skeletal, isotic over mixed, mesic Vitrandic Haploxerolls), with exposure to full sun. Six repetitions were conducted on sand-based simulated putting green or tee surfaces. Three of these were located in full sun. The remaining three were in a shaded area surrounded on the west, south, and east by stands of deciduous trees approximately 20 m in height. Clearances between trees and the experimental site were approximately 5, 10, and 15 m on the west, south, and east sides, respectively. The proximity and height of the trees were such that the plots received almost no direct, unfiltered sunlight. The only direct light on the plots was from sunflecks. Light quantity and quality were not monitored continuously during the experiments, but periodic measurements indicated that the site received approximately 30 to 50% of the light intensity received on the full sun site.

The sand-based site in full sun was constructed in March of 1999. Sand conforming to United States Golf Association particle size distribution recommendations (Hummel, 1993) was installed to a depth of approximately 30 cm. No organic matter or other soil amendments were incorporated into the sand. The shaded sand-based site was constructed similarly in May 1999 and expanded in August 1999. The native soil site was previously established to various species of fine-leafed fescue (Festuca spp.). The area was sprayed with glyphosate (phosphonomethylaminoacetic acid) at the rate of 4 kg a.i. ha^–1 in the spring of 1998, followed by disking and rotovating several times through the spring of 1999 to aid in decomposition of the sod layer. Final grading was accomplished by hand raking just before initiation of the experiment. Seeding dates were 27 May 1999, 16 Sept. 1999, and 30 May 2000 on sand in full sun; 27 May 1999, 16 Sept. 1999, and 31 May 2000 on sand in partial shade; and 27 May 1999 on the fine sandy loam soil. For each repetition on sand, a new, previously unplanted plot area was used.

Soil preparation, seeding, and mulch treatment applications were identical in all seven repetitions of the experiment. Before seeding, a 19–11–4 (N–P–K) starter fertilizer (Scott's Contec, The Scotts Company, Marysville, OH) was applied uniformly to all plot areas at the rate of 4.9 g N m^–2, and was then lightly raked into the soil surface. True-Putt creeping bluegrass was applied at the rate of 9.8 g pure live seed m^–2 using a drop spreader, applying one-half of the seed in each of two perpendicular directions. Seed was then raked lightly into the soil surface (approximate depth 3–6 mm). Immediately following seeding, mulch treatments were applied to plots measuring 1.2 m x 1.5 m, with five replicates in a randomized complete block design. The four mulch treatments were (i) sphagnum peat moss, applied at the rate of 2.5 L m^–2, resulting in a layer of peat averaging 2.5 mm in depth (based on plot size and application rate); (ii) pelletized paper seed mulch (Seed Aide, Aimcor Consumer Products, Buffalo Grove, IL), applied at the rate of 368 g m^–2 (highest label rate); (iii) polypropylene fabric (Seed Guard, American Agrifabrics, Alpharetta, GA), one layer; and (iv) an unmulched control. These treatments were chosen to represent a range of options based on availability, ease of use, and their potential long-term impacts on the soil surface. Peat moss is sometimes applied as a mulch, but it can be difficult to apply, and the resulting organic layer on the surface of the sand could potentially impede water infiltration or promote disease. Pelletized paper mulch can be applied by hand or with a rotary fertilizer spreader, simplifying application compared with peat. Creation of a surface organic layer may still be a concern, but this material appears to break down more quickly than peat, although data concerning this is lacking. The final mulch treatment was a permeable polypropylene seed germination fabric. This was removed from the plots 10 to 12 d after seeding, depending on the germination time for each experiment. Removal of the fabric eliminates the potential of a surface organic layer. Following seeding and treatment application, plots were irrigated lightly three times daily to maintain surface moisture. After seedlings emerged, plots were irrigated as needed to maintain favorable growing conditions.

Plots were monitored for the number of days until seedling emergence, and were rated for percentage cover by seedlings on a 0-to-100 scale at 2, 3, 4, and 6 wk after planting (WAP). Percentage cover was defined as the relative proportion of visible plant tissue to visible soil surface. Because differences in growth rates among plots became apparent, a visual rating of plant height was made once during each study, using a scale of 1 to 9 (1 = no plants, 9 = tallest). Plant density was also rated using a 1 to 9 scale (1 = no plants, 9 = maximum density) at the conclusion of each study. Density was distinguished from percentage cover by taking into account the appearance of multiple leaves and/or tillers on individual plants. Plots with similar percentage cover ratings could have different density ratings based on leaf and tiller emergence rates. Days to emergence and density ratings were not collected from studies seeded in May 2000.

The six repetitions of the experiment on sand-based media were combined for statistical analysis. The experimental protocol consisted of a split-plot experimental design with three factors: mulch, light, and date of planting (DOP). The whole plot consisted of a factorial treatment structure of light (sun vs. shade) and DOP, with five replications per treatment combination. Replications were nested within whole plots. The subplot design structure was a randomized complete block with a one-way treatment structure (mulch at four levels).

The single repetition of the experiment conducted on the fine sandy loam soil was analyzed separately because it was only conducted once at this site and the soil conditions were different from the other repetitions. The experimental design was a randomized complete block with a one-way treatment structure (mulch at four levels) with five replications.

Statistical analysis was conducted using the General Linear Model procedure of SAS v. 8 (SAS Institute, Cary, NC). When significant F tests existed, means separations were conducted using Fisher's Protected LSD (P = 0.05).

	RESULTS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
The six experiments conducted on sand-based media in sun and partial shade had significant mulch x light x DOP interactions for days to emergence and percentage cover at 3 and 4 WAP; significant mulch x DOP interactions for emergence and percentage cover at 2 and 6 WAP; and significant light x DOP interactions for emergence, percentage cover at 2, 3, and 4 WAP, and plant height at 3 WAP (Table 1). These interactions were probably due at least in part to weather. Mean daily air temperatures during the 6 wk following the May 1999 and May 2000 plantings were 14.5 and 15.6°C, respectively. Temperatures during the first 10 d after planting in September 1999 averaged 14.5°C, but dropped sharply after that, resulting in a mean of 10.7°C over the 6-wk period. Data were subsequently analyzed separately for each DOP, examining mulch and light main effects and interactions.

For the September 1999 seeding date there were no differences in seedling emergence due to mulch treatment (Table 4). The peat mulch resulted in the highest percentage cover at 2, 3, and 4 WAP, while fabric was second best. Pellets and the unmulched control were significantly lower. By 6 WAP there were no differences in cover due to mulch treatment. Peat plots had the greatest plant height at 3 WAP, fabric and pellets were intermediate, and the unmulched control was the lowest. Mulch treatment did not significantly affect plant density. Seedling emergence occurred earlier and density was higher in the sun than the shade, while plant height was higher in shade. Percentage cover was significantly higher in the sun than the shade at 2 and 6 WAP. Compared with the May 1999 seeding, cover was not achieved as quickly in the fall.

	DISCUSSION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

Seedlings emerged earlier in the sun than in the shade under fabric mulch in spring 1999 (Table 3), and emergence also occurred earlier in the sun in fall 1999 (Table 4). Enhanced soil warming in the full sun probably contributed to this. Bell and Danneberger (1999) measured higher canopy temperatures in full sun vs. shade. Despite this trend for earlier emergence in the sun, there were no consistent patterns in establishment rate, measured as percentage cover, between the sunny and shaded sites. Percentage cover was higher in shaded plots than in full sun from 2 through 4 WAP in spring 1999 (Table 2), higher in full sun plots at 2 and 6 WAP in fall 1999 (Table 4), and not significantly different in spring 2000 (Table 5). This is similar to observations by Murphy et al. (2001), who saw no consistent differences in establishment rates between a site with open exposure and one bordered by trees from the southwest to the southeast exposures. Comparisons of seeding dates show that seeding in late May resulted in quicker cover than seeding in mid-September, although this was not statistically analyzed. At 4 WAP in spring 1999, fall 1999, and spring 2000, percentage cover averaged 82, 55, and 75%, respectively.

In a fine sandy loam soil not subject to shade, seeding of True-Putt creeping bluegrass resulted in rapid establishment, even without the use of a mulch (78% cover at 3 WAP, 100% cover at 4 WAP) (Table 6). In many situations, this establishment rate may be acceptable, and so mulch may not be needed on similarly textured soils, provided that irrigation is available to maintain surface moisture. The polypropylene fabric mulch was the only treatment that resulted in significantly faster establishment than the control (66% and 95% cover at 2 and 3 WAP, respectively). Seedling emergence in as little as 4 d (mean of 4.8 d) under the fabric played a role in this. This product also resulted in the fastest vertical growth rate through 3 WAP. The fabric cover would be useful when rapid stand establishment is desired. Although the design of the experiment did not allow for direct statistical comparisons, turf appeared to establish more quickly in the fine sandy loam than in sand-based media. Higher water holding capacity and darker color, resulting in more soil warming, were probably contributing factors. Murphy et al. (2001) attributed higher establishment rates on medium-fine-textured sand mixes compared with coarser-textured sand mixes to greater soil moisture retention.

It is important to note that throughout the course of these experiments, grass was not subjected to player traffic or mowing, as they might be on a golf course. These activities would probably impact the establishment rate. The fact that plots achieved nearly full cover in 4 to 6 weeks does not mean that they would be ready for continuous play in that period of time. Factors such as mowing height and topdressing for smoothness would also impact this. These experiments did show that True-Putt creeping bluegrass has the potential to establish rapidly and effectively. Seedling emergence occurred in as little as 4 d in fine sandy loam soil, and within 8 d on sand. Full cover was attained more quickly following May seeding than September seeding. Differences between full sun and shaded sites were not substantial. The pelletized paper mulch product used in these experiments was not statistically better than the unmulched control in most cases. This product could not be recommended for use on sand-based media based on the results of these experiments. Peat was the most effective mulch in enhancing seedling emergence, cover, and vertical growth. Peat can be highly variable, so results may differ for other peat products. Polypropylene fabric was almost as effective as peat. If introduction of an organic layer that can potentially alter soil physical properties is a concern, the fabric would be the best choice. Other advantages of the fabric include ease of installation and removal, and golfers would not be inclined to walk or play over the area during the establishment period.

	ACKNOWLEDGMENTS

 
The authors would like to acknowledge Dr. Marc Evans, Program in Statistics, Washington State University, for his assistance with experimental design and statistical analysis.

	NOTES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Research supported by the Washington Agricultural Research Center and Northwest Turfgrass Association. CSS Dep. Sci. Paper No. 0303-01.

Received for publication August 29, 2003.

	REFERENCES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 

• Barkley, D.G., R.E. Blaser, and R.E. Schmidt. 1960. Effect of mulches on microclimate and turf establishment. Agron. J. 52:159–162.[Abstract/Free Full Text]
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• Beard, J.B. 1999. Poa annua terminology clarified. TURFAX 7(4):3.
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• Bell, G.E., and T.K. Danneberger. 1999. Temporal shade on creeping bentgrass turf. Crop Sci. 39:1142–1146.[Abstract/Free Full Text]
• Bell, G.E., T.K. Danneberger, and M.J. McMahon. 2000. Spectral irradiance available for turfgrass growth in sun and shade. Crop Sci. 40:189–195.[Abstract/Free Full Text]
• Brauen, S.E. 1988. Establishment of bentgrass putting greens with coated seed and hypnum peat. p. 27–34. In Proc. of the 42nd Northwest Turfgrass Assoc. Annual Conf., Spokane, WA. 19–22 Sept. 1988. Northwest Turfgrass Assoc., Spokane, WA.
• Dudeck, A.E., and C.H. Peacock. 1992. Shade and turfgrass culture. p. 269–284. In D.V. Waddington et al. (ed.) Turfgrass. Agron. Monogr. 32. ASA, CSSA, and SSSA, Madison, WI.
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• Hummel, N.W., Jr. 1993. Rationale for the revisions of the USGA green construction specifications. USGA Green Sect. Rec. 31(2):7–21.
• Murphy, J.A., J.A. Honig, H. Samaranayake, T.J. Lawson, and S.L. Murphy. 2001. Creeping bentgrass establishment on root zones varying in sand sizes. Int. Turfgrass Soc. Res. J. 9:573–579.
• Toole, V.K., and H.A. Borthwick. 1971. Effect of light, temperature, and their interactions on germination of seeds of Kentucky bluegrass (Poa pratensis L.). J. Am. Soc. Hortic. Sci. 96:301–304.
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This Article Abstract Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Miltner, E. D. Articles by Johnston, W. J. Search for Related Content PubMed Articles by Miltner, E. D. Articles by Johnston, W. J. Agricola Articles by Miltner, E. D. Articles by Johnston, W. J. Related Collections Turfgrass Management Turfgrass Seed Establishment