A 10-year evaluation of plant growth regulator carryover in roadside test plots in Indiana

Abstract

Three primary growth regulators/ herbicides, mefluidide, chlorsulfuron and sulfometuron, alone and in combinations with and with-out surfactant or 2,4-dichlorophenoxyacetic acid (2,4-D), were applied annually eight to 10 times the cost-effective rates of application to roadside stands of mixed tall fescue (Festuca arundinacea Schreb.) and native bluegrass (Poa pratensis L). The plots were not mowed. Applications were during the first week of May prior to elongation of culms bearing seed heads. With all of the materials and at all rates of applications, the grass had recovered fully by the end of the growing season (August). Even in the final year of the trial, all plots still supported strong stands of perennial grasses. The results show that the growth retardant mefluidide alone or in combination with the sulfonylurea herbicides, chlorsulfuron or sulfometuron, can be applied to established turf at cost-effective rates on an annual basis with-out permanent damage to turf or detrimental carry-over of materials.