Abstract

Supina bluegrass (Poa supina) is being increasingly used for shaded lawns and golf course tees due to its excellent shade tolerance. The herbicide tolerance, however, is undocumented because herbicide use on amenity turfs is banned in the European countries where supina bluegrass has been used for over 30 years. Several commonly used turf and ornamental herbicides are capable of harming or eradicating close relatives of supina bluegrass. In particular, Prograss (Ethofumesate) is used to selectively remove annual bluegrass (Poa annua) from mixed turf stands. Supina bluegrass is a putative ancestor of annual bluegrass and may have similar susceptibilities to chemicals. Fifteen pre and postemergence turf and ornamental herbicides were tested for their potential to damage or kill a mature stand of supina bluegrass. Field trials were conducted twice over two growing seasons. Herbicides with the active ingredients triclopyr, MCPP, quinclorac, and ethofumesate caused temporary phytotoxicity in at least one of the two years. Fall applications of Prograss (Ethofumesate) and Turflon Ester (Triclopyr) caused phytotoxicity the spring following autumn application in both years, while Strike 3 (Dicamba, MCPP, 2,4-D) and Confront (Triclopyr + Clopyralid) caused phytotoxicity in one year only. None of the compounds showed potential for selectively removing supina bluegrass from a mixed turf stand.