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© 2007 Plant Management Network.
Accepted for publication 27 April 2007. Published 6 August 2007.

Golf Course Putting Green Rootzone and Establishment Effects on Pythium Foliar Blight on Creeping Bentgrass

Jason D. Lewis, Roch E. Gaussoin, and Robert (Bob) C. Shearman, 362 Plant Science, Department of Agronomy and Horticulture, University of Nebraska, Lincoln 68583-00915; and Loren J. Giesler, 402 Plant Science, Department of Plant Pathology, University of Nebraska, Lincoln 68583-0722

Corresponding author: Roch E. Gaussoin. rgaussoi@unlnotes.unl.edu

Lewis, J. D., Gaussoin, R. E., Shearman, R. C., and Giesler, L. J. 2007. Golf course putting green rootzone and establishment effects on pythium foliar blight on creeping bentgrass. Online. Applied Turfgrass Science doi:10.1094/ATS-2007-0806-01-RS.

Abstract

Turfgrass establishment on sand rootzones can be challenging. The original objective of this study was to evaluate the effects of rootzone mixtures and establishment treatment on soil physical, chemical, and biological properties with time. Reported here are serendipitous findings relating Pythium foliar blight injury associated with applied treatments. USGA specification putting greens were constructed sequentially from 1997 to 1999. Treatments included two rootzones (80% sand and 20% sphagnum peat, and 80% sand 15% sphagnum peat and 5% Tomek silty clay loam v:v) and two establishment treatments (accelerated and controlled). Relative to the controlled treatment, the accelerated treatment received 2.6, 3.0, and 2.6 fold N, P, and K, respectively. Greens were established with Providence creeping bentgrass (Agrostis stolonifera L.). Pythium foliar blight injury [(Pythium aphanidermatum) (Edson) Fitzp.] was observed approximately four to six weeks after planting despite using a preventative fungicide program. The controlled establishment treatment had 58% less Pythium injury than the accelerated treatment. The accelerated treatment did not enhance turfgrass cover or readiness for play, suggesting that elevated nutritional levels did not facilitate rapid establishment due to increased disease and probable environmental stress susceptibility.

Introduction

Turfgrass establishment on sand based putting green rootzones presents a challenge to golf course superintendents. Reduced nutrient holding capacity and increased disease incidence during establishment on USGA rootzones are among the problems encountered on high sand content rootzones (14,16). Agronomists from the USGA often encourage practices to promote rapid turfgrass establishment on USGA specification putting greens with the intent of quickly stabilizing the rootzone (16). Limited research has been conducted on establishment procedures that expedite bringing putting greens into play, with minimal impact on turfgrass quality and performance.

High nutrient inputs have been reported to increase turfgrass cover during establishment (2,14,16), but increased inputs may also reduce turfgrass quality due to decreased depth and extent of root development (3,4). Increased N-nutritional levels results in decreased root growth due to carbohydrate reallocation for shoot growth (3,4).

Pythium foliar bight is a major disease affecting putting greens. It is caused by several Pythium species, while generally considered root pathogens they can also cause crown and foliar blight (4,6,13). It has been associated with nutritional levels that exceed turfgrass nutritional needs (2,4,11,13). Numerous researchers have reported increased Pythium foliar blight incidence in juvenile and succulent plant tissues when fertilized with excessive N (4,9,10,13).

The objective of this study was to evaluate the effects of rootzone mixtures and establishment treatment on soil physical, chemical, and biological properties with time. The soil chemical characterization associated with this study has been previously reported (8). However, a consistent and serendipitous treatment response related to Pythium foliar blight was observed; therefore data were collected and will be reported and discussed in this paper.

Putting Green Establishment

Research was conducted at the John Seaton Anderson Turfgrass Research Facility located near Mead, NE. Three experimental putting greens were constructed following USGA specifications (12) in consecutive years, from 1997 to 1999 (8). The greens were seeded with ‘Providence’ creeping bentgrass at 7.5 g/m². Treatments included two rootzones [80% sand and 20% sphagnum peat, and 80% sand, 15% sphagnum peat, and 5% Tomek silty clay loam (fine smectitic, mesic Pachio Argiudoll) v:v] and two establishment treatments, accelerated and controlled. Golf course superintendents and USGA agronomists with putting green establishment experience were surveyed for their recommendations for establishment procedures. Their recommendations were used to set the establishment treatments. The accelerated establishment treatment incorporated high nutrient inputs and was intended to encourage rapid turfgrass cover, while the controlled treatment was based on agronomically sound practices based on recommendations from local turfgrass specialists (8).

Pre-plant fertilizer was incorporated into approximately the upper 2.54 cm of the rootzone with a hand rake prior to seeding. Post planting/germination, the accelerated treatment received fertilizer applications weekly, the controlled treatment received fertilizer applications every two weeks. All fertilizers were obtained from The Andersons Co. (Maumee, OH) . Pre-plant and post-plant fertilizer applications constituted 20% and 50% water soluble nitrogen, respectively. The total amount of N, P, and K applied in the accelerated treatment was two times and four times the amount of the controlled treatment for pre-plant and post-plant applications, respectively, in the establishment year. A more comprehensive description of nutrient inputs can be found in McClellan et al (8).

Experimental Design

Within each year, treatments were arranged in a 2 × 2 (rootzone mixture × establishment procedure) factorial. Each experimental unit was 4.6 × 7.6 m. Experimental design was a randomized complete block design with three replications. The first experimental area was constructed in 1996. The rootzones settled over the winter and were seeded 30 May 1997. The same procedures were used for construction and seeding of experimental greens in 1998 to 1999. Management practices included: (i) mowing daily at 3mm with clippings removed; (ii) irrigation at 80% of potential evapotranspiration; (iii) sand topdressing applied at 4.9 × 10^-4 m³/m² combined with vertical mowing every 10 to 14 days based on turfgrass growth; and (iv) preventative pest management practices.

All plots received preventative fungicide applications of mancozeb (Fore, Dow AgroSciences, Indianapolis, IN), azoxystrobin (Heritage, Syngenta, Greensboro, NC), propamocarb hydrochloride (Banol, Bayer, Montvale, NJ), mefenoxam (Subdue, Syngenta, Greensboro, NC), aluminum tris (Aliette, Aventis Environmental Services, Montvale, NJ and Signature, Bayer, Montevale, NJ), iprodione (26GT, Bayer, Research Triangle Park, NC and Chipco 26019, OHP Inc., Mainland, PA) and chorothalonil (Daconil Ultrex, Syngenta, Greensboro, NC). Preventative applications began in early June and continued on approximately 14-day intervals thereafter until early September in each year. Specific fungicides rates and application dates are shown in Table 1. 

Table 1. Fungicide application schedule for establishment year on ‘Providence’ creeping bentgrass for USGA specification greens located at Mead, NE, from 1997 to 1999.

Data Collection and Analysis

A treatment related turfgrass cover decline was observed in late June or early July of all four establishment years with a causal agent identified as a Pythium aphanidermatum. Identification of the Pythium species involved was achieved by platting infected foliage onto water agar and isolating the causal agent. Virulence of the pathogen was confirmed by Koch’s postulates. Purified isolates were maintained in culture for observations to identify the species by standard methods to initiate sexual structures for observation (1,7). Based on morphological characteristics of oospores and antheridia, the causal agent was identified as P. aphanidermatum. Visual estimates of Pythium foliar blight injury were taken when disease symptoms became evident, using a visual rating scale of 1 to 9 with 1 = no injury and 9 = 90-100% injury.

Turfgrass quality and color ratings were taken two to three weeks after disease symptoms were observed. Turfgrass quality measurements were made using a visual rating scale of 1 to 9, with 1 = poorest, 6 = acceptable, and 9 = best. Turfgrass color ratings were made using a 1 to 9 visual rating scale with 1 = straw brown, 6= light green and 9 = dark green.

Data were analyzed by ANOVA using SAS in a mixed model design, and means were separated using Fisher’s protected least significant differences (LSD) at P = 0.05. Hartley’s F-max test (P = 0.05) was performed for test of homogeneity of variance across years (5).

Establishment Treatment Influences on Pythium Foliar Blight

The Hartley’s F-max test indicated that data across all three years could be combined for turfgrass color and quality, but not for Pythium foliar blight injury. Establishment treatments were a significant source of variability for Pythium foliar blight (Table 2). The greatest amount of Pythium foliar blight occurred in the accelerated treatment. Pythium foliar blight developed even though preventative fungicide treatments were applied. Elevated N-nutrition may have caused succulent shoot growth and increased susceptibility to P. aphanidermatum. Other researchers have reported similar observations (4,9,10,13). The sand-peat-soil rootzone had lower Pythium foliar blight injury in 1999 (data not shown). While this response was only significant in one of three years the addition of soil in the rootzone mixture may have increased water holding capacity and nutrient retention, which would improve turfgrass growing conditions and enhance recuperative potential (15).

Table 2. Mean turfgrass Pythium injury as affected by establishment treatment and rootzone mixture for USGA putting greens located at Mead, NE. Data were collected from the establishment year of three putting greens constructed from 1997 to 1999.

*, **, ***, and NS = significant F test at the 0.05, 0.01, 0.001 level of probability and non-significant, respectively.

 ^x Visual estimates of Pythium blight severity were taken when disease symptoms became evident, using a visual rating scale of 1 to 9 where 1 is no injury and 9 is 90 to 100% injury.

 ^y Means in the same column followed by a different letter are significantly different based on Fisher's protected LSD (P = 0.05).

The accelerated treatment had higher turfgrass color ratings. This response likely reflected the higher nitrogen, iron and other nutrients applied in the accelerated treatment. The accelerated establishment treatment received lower turfgrass quality ratings than the controlled treatment, primarily due to increased Pythium foliar blight injury, reduced turfgrass cover, and slower recovery (Table 3).

Table 3. Pooled turfgrass quality and color as affected by establishment treatment and rootzone mixture for USGA putting greens located at Mead, NE. Data were collected from the establishment year of three putting greens constructed from 1997 to 1999, two to three weeks following Pythium foliar blight infection. Data were pooled from the establishment year of the putting greens based on homogeneity of variance.

*,**,***, and NS = significant at the 0.05, 0.01, 0.001 and non-significant, respectively.

 ^x Turfgrass quality measurements were taken visual using a 1 to 9 rating scale, where 1 is poorest, 6 is acceptable, and 9 is best turfgrass quality.

 ^y Turfgrass color ratings were taken visually using a 1 to 9 rating scale, where 1 is straw brown and 9 is dark green turfgrass color.

 ^z Means in the same column within the same factor followed by the different letter are significantly different based on Fisher's protected LSD (P = 0.05).

Rootzone mixture had little influence on turfgrass color and quality ratings. A high nutrient fertilizer program aimed at increasing turfgrass cover development may result in increased Pythium foliar blight injury and less turfgrass recovery, even when preventative fungicides are applied. The controlled treatment was more agronomically sound for creeping bentgrass establishment on sand based putting greens. Under our growing conditions, the accelerated treatment did not enhance turfgrass cover development or readiness for play, indicating that elevated nutritional levels may not facilitate rapid establishment due to increased disease incidence and probable environmental stress susceptibility. When suboptimal seeding times are used and/or in areas prone to Pythium spp. outbreaks, excessively high nutritional inputs during grow-in should be avoided.

Acknowledgments

The authors express thanks to the United States Golf Association, The Environmental Institute for Golf, and the Nebraska Turfgrass Association for providing financial support for this research. The authors would also like to thank Leonard Wit and Jeff Witkowski for their assistance in plot maintenance.

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