TifGrand bermudagrass seedhead control with herbicides and plant growth regulators.

Abstract

TifGrand™ bermudagrass has desirable color, texture, and shade tolerances for fine turf, but prolific seedhead
production may reduce quality. Acetolactate synthase (ALS) inhibiting herbicides have potential to regulate bermudagrass growth, and may provide alternatives to growth regulators for seedhead control. Field experiments
were conducted to evaluate efficacy of six ALS inhibitors for TifGrand bermudagrass seedhead control over 9 wks. Sequential applications of flucarbazone-sodium at 60 g a.i. ha-1 3 wk-1 and nicosulfuron at 53 or 105 g a.i. ha-1 3 wk-1 provided good (80 to 89%) to excellent (90%) control of bermudagrass seedheads on the majority of evaluation dates in both years, and were comparable to ethephon plus trinexapac-ethyl at 3820 + 44 g a.i. ha-1 3 wk-1. Ethephon plus trinexapac-ethyl, flucarbazone-sodium, and both nicosulfuron rates caused unacceptable (>20%) injury on 5, 2, and 0 out of 17 evaluations, respectively. Sequential applications of other herbicides including, flazasulfuron at 26 or 52 g a.i. ha-1, foramsulfuron at 44 g a.i. ha-1, metsulfuron-methyl at 21 g a.i. ha-1, and trifloxysulfuron-sodium at 29 g a.i. ha-1, provided poor (<70%) seedhead control on most evaluations, but caused <10% injury. Overall, flucarbazone-sodium and nicosulfuron appear to have potential for controlling TifGrand bermudagrass seedheads as an alternative to PGRs currently used in turfgrass.