Effects of Glyphosate and Siduron on Turfgrass Establishment

The effects of several concentrations of glyphosate [N-(phosphonomethyl)glycine] and siduron [1-(2-methylcyclohexyl)-3-phenylurea] on germination and seedling growth of Kentucky bluegrass (Poa pratensisL. ‘Nugget,’ ‘Prato,’ ‘Fylking,’ ‘Park’), creeping bentgrass (Agrostis palustrisHuds. Penncross,’ ‘Seaside’), and red fescue (Festuca rubraL. ‘Pennlawn,’ ‘Wintergreen’) were evaluated in petri dishes under controlled environmental conditions. A high concentration of glyphosate (10-4M) reduced shoot growth in all but two cultivars. Siduron had no effect. Glyphosate or siduron applied to the soil and incorporated did not affect turfgrass germination or growth. When the glyphosate was sprayed over the soil and on the seed lying on the soil surface, red fescue germination was reduced and shoot growth of Kentucky bluegrass, creeping bentgrass, and red fescue was inhibited at the high rate of glyphosate application (17.9 kg/ha). Under field conditions, none of the glyphosate treatments reduced turfgrass germination or growth.