Plant Growth Regulators on Bentgrass Putting Green Turf
Horticulture Department
Introduction
Creeping bentgrass is the preferred turfgrass for golf course putting green turf. In the Southern United States bentgrass, a cool season turfgrass, is often under increased environmental stress. Bentgrass with proper management; however, will provide 12 months of green color. Plant growth regulators (PGRs) provide the potential to enhance turfgrass color, reduce mowing and reduce fertilizer requirements. Some PGRs have shown a potential to control invasion and/or survival of annual bluegrass, a major weed species in putting green turf.
Objectives
Determine the influence of several plant growth regulators on the quality, maintenance and weed control of bentgrass putting green turf.
Procedures
PGR treatments included paclobutrazole at .125 ai/A, ethofumesate at .38 ai/A and cyclohydroxymethylene 0.5 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 Penncross creeping bentgrass green mowed at 3/16". The green 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 green received 8 lb N (methylene urea), 2 lb P2O5 and 4 lb K2O from a complete fertilizer. The green received standard cultural practices to include preventative fungicide sprays, aeration and topdressing. Turf was irrigated so as to avoid wilt.
Results
Both paclobutrazole and cyclohydroxymethylene enhanced bentgrass quality over the control during the Fall of 1995. Ethofumesate reduced turf quality with respect to the control during the same period. During January and February paclobutrazole enhanced turf quality over the other treatments. During March and April ethofumesate had higher quality than the other treatments. Cyclohydroxymethylene was superior in turf quality to other treatments during May and June. The 1995-96 average showed that paclobutrazole and cyclohydroxymethylene enhanced turf quality with respect to the control during the test period. Ethofumesate reduced turf quality with respect to the control during the same period.
The average population of Poa annua in the control plots during the study was 16%. Both paclobutrazole and ethofumesate treatments significantly reduced the level of Poa annua to 9.3 and 2.4%, respectively. Cyclohydroxymethylene treated plots had 24%, which was significantly greater than the control.
Table 1. Turf scores of Penncross creeping bentgrass treated with plant growth regulators and herbicide at Clemson, SC.
Table 2. Percent Poa annua b in Penncross creeping bentgrass treated with plant growth regulators and herbicide at Clemson, SC.