Shane Parker (1), Bruce Martin (1), James Camberato (1), Steven Jeffers (2)
(1) Pee Dee Research and Education Center, Florence, SC 29505
(2) Clemson University, Clemson, SC 29635

Introduction

     Bermudagrass is commonly used for greens and fairways on South Carolina golf courses. Bermudagrass is noted for its heat, disease and drought tolerance, making it well adapted to the warm, humid conditions prevalent during South Carolina summers. Overseeding of bermudagrass with rough bluegrass is performed annually to provide a smooth, green putting surface during the dormancy period of the bermudagrass. The spring transition from rough bluegrass to bermudagrass can be particularly difficult due to sudden climatic changes such as periods of high and low temperature extremes, and the subclinical activity of soil-borne pathogens, such as Pythium, Bipolaris, Fusarium and others. The utilization of sound management practices during spring transition are of particular importance to South Carolina golf courses because this is the period of premium golf prices and high volume of play. In previous experiments, Martin, Camberato, and Liu showed that fungicides applied in the spring for disease control on rough bluegrass could affect the quality of the turf during and after transition. This report describes further experiments conducted to investigate potential effects of fungicides targeted for Pythium species that might affect health of bermudagrass and spring transition.

Methods and Materials

     In this study, experiments were established at two locations, Pee Dee Research and Education Center in Florence, S.C. and the Sun City golf courses at Hilton Head, S.C. At each location, TifDwarf and TifEagle bermudagrass cultivars were utilized. The TifDwarf and TifEagle putting greens were selected for uniformity and 3’ x 5’ plots were laid out with four replicates per cultivar and six fungicide treatments per replicate. The experimental design was a randomized complete block.
     Each fungicide treatment was applied at labeled rates. The rates were: Aliette Signature (4 oz./1000 sq. ft.), Fore Rainshield (8 oz./1000 sq. ft.), Heritage (0.4 oz./1000 sq.ft.), Subdue Maxx (1 fl. oz./ 1000 sq. ft.), Aliette Signature + Fore Rainshield tank mix (4 & 8 oz./1000 sq. ft., respectively), and an untreated control. Treatments were applied on a 21 day schedule with applications on 25/26 April, 16/17 May, and 6/7 June. Prior to each of the last two applications the plots were rated for turf quality (0-9, 9=perfect). Plot rating continued on a 21 day schedule until 11 July. The Least Significant Difference Test (LSD) with a P<0.05 was utilized to determine treatment differences.
 

     Significant improvements in turf quality occurred with the application of several fungicides on TifEagle greens while similar quality improvement trends were noted in TifDwarf greens. Significant treatment effects were found at the first rating date in TifEagle on 6 June, 21 days after the second treatment application. The greatest treatment effect on this date was with the combination of Aliette Signature + Fore Rainshield (Figure 1). The Fore Rainshield treatment and Heritage treatment were also found to have significant effects when compared to control plots on the 6 June date. Thirteen days after the final treatment application of the 19 June rating date, significant treatment effects were noted for Fore Rainshield, Heritage, Aliette Signature and the combination of Aliette Signature + Fore Rainshield when compared to the control. The 11 July rating date for TifEagle, 35 days after the last treatment application, resulted in significant treatment effects noted in the Aliette Signature + Fore Rainshield combination only.

    Similar results were noted in TifDwarf compared to TifEagle, with the greatest improvements in turf quality form Aliette Signature + Fore Rainshield 21 days after the second treatment application on 6 June (Figure 2). Significant improvements in turf quality were also noted 13 days after the last treatment application on 19 June with Aliette Signature, Fore Rainshield, and the Aliette Signature + Fore Rainshield combination. By 35 days after the last treatment application on 11 July, the treatment effects in TifDwarf had dissipated to a level that was not statistically significant.

 
     Subdue Maxx did not affect the turf quality of either TifDwarf of TifEagle when compared to the control plots. Subdue Maxx has an activity range limited to Oomycetes, thus these results suggest that Pythium spp. were not adversely affecting the rough bluegrass or the bermudagrass during the period of spring transition. These data suggest that the combination treatment of Aliette Signature + Fore Rainshield provided the earliest, greatest, and longest lasting improvements in turf quality of rough bluegrass and bermudagrass greens in this study.

Photo 1. Turf quality improvement of TifEagle bermudagrass treated with Aliette Signature + Fore Rainshield (4 + 8 oz/1000 sq.ft., 2x, 21 day) on left, compared with Subdue Maxx (1 fl oz/1000 sq.ft., 2x, 21 day) on right.

Photo 2. Turf quality improvement of TifDwarf bermudagrass treated with Aliette Signature + Fore Rainshield (4 + 8 oz/1000 sq.ft., 2x, 21 day) on right, with untreated turf on the left.
 

Poster presentation at the Clemson University Turfgrass Field Day, Sept. 10, 2002

 

Highlights from Turfgrass Field Day 2002      Disease Management Bermudagrass