Plant Growth Regulators on Overseeded Hybrid Bermudagrass Tee

and Fairway Turf

A. R. Mazur

Horticulture Department

Introduction

Hybrid bermudagrass is the standard turfgrass for golf course tee turf in the Southern United States. Hybrid bermudagrass provides high quality with proper management during the warm months; however, it must be overseeded during the winter to provide green color and resilient playing surfaces. Plant growth regulators (PGRs) provide the potential to reduce bermudagrass competition during the Fall transition as well as enhance turfgrass color, reduce mowing and reduce fertilizer requirements. Some PGRs have also shown a potential to control invasion and/or survival of annual bluegrass a major weed species in turf.

Objectives

Determine the influence of several plant growth regulators on the on quality, maintenance and weed control on overseeded bermudagrass tee turf.

Procedures

PGR treatments included paclobutrazole at .25 and .38 ai/A and cyclohydroxymethylene 0.25 oz/1000 sq. ft. The PGRs were applied as per label recommendations using a CO2 sprayer in water at a rate of 20 gal/A. Treatments were applied to a Tifway (419) hybrid bermudagrass tee mowed at 1/2". The tee was overseeded with annual bluegrass on 9/15/95 at a rate of 1 lb per 1000 sq ft to insure a uniform weed population. The tee received 4 lb N (methylene urea), 1 lb P2O5 and 2 lb K2O from a complete fertilizer. The tee received standard cultural practices to include thatching and aeration. Turf was irrigated so as to avoid wilt. The tee was overseeded with Yorktown II perennial ryegrass at the rate of 14.4 lb per 1000 sq ft on 10/11/95 using standard overseeding practices.

Results

During October and November paclobutrazole at both rates had significantly higher quality than cyclohydroxymethylene and the control. Paclobutrazole treated plots , particularly the .38 rate, had less turf quality than the control and cyclohydroxymethylene during January. During April, May, and early June paclobutrazole at the .38 rate had significantly higher turf quality than the control and cyclohydroxymethylene treatments. This was true again in July. The 1995-96 average showed that cyclohydroxymethylene prior to establishment increased turf quality over paclobutrazole treatments and the control.

The average population of Poa annua in the control plots during the study was 36%. Paclobutrazole treatments significantly reduced the level of Poa annua to 18 and 12% at the .25 and .38 rates respectively. Cyclohydroxymethylene treated plots were not significantly different than the control.

Table 1. Turf scores of Tifway hybrid bermudagrass overseeded with Yorktown II perennial ryegrass and treated with plant growth regulators and herbicide at Clemson, SC.

Table 2. Percent Poa annua in Tifway hybrid bermudagrass overseeded with Yorktown II perennial ryegrass and treated with plant growth regulators and herbicide at Clemson, SC.