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Abstract
Star-of-bethlehem (Ornithogalum umbellatum) commonly invades turfgrass stands throughout the transition zone. Field experiments were conducted to evaluate sulfentrazone and mixtures of mesotrione and topramezone with bromoxynil and bentazon for selective star-of-bethlehem control in cool-season turf. At 4 weeks after treatment (WAT), applications of sulfentrazone at 0.25 and 0.38 lb/acre provided >95% control of star-of-bethlehem in 2008 and 2009. Star-of-bethlehem control following applications of commercial prepackaged mixtures containing sulfentrazone was not significantly different from applications of sulfentrazone alone, at either rate, at 4 WAT in 2008 and 2009. Control with carfentrazone-ethyl at 0.03 lb/acre measured to <75% at 4 WAT each year. Star-of-bethlehem control at 2, 3, and 4 WAT with topramezone at 0.033 lb/acre was increased by 77%, 50%, and 46%, respectively, from the addition of bromoxynil at 0.50 lb/acre. Similarly, the inclusion of bromoxynil at 0.50 lb/acre increased the level of control observed following treatment with mesotrione at 0.28 lb/acre by 77%, 30%, and 32% at 2, 3, and 4 WAT. These data suggest that sulfentrazone and mixtures of topramezone and mesotrione with bromoxynil can be used to provide postemergence control of star-of-bethlehem in cool-season turf.
Star-of-bethlehem is a perennial weed of managed turfgrass areas throughout the upper transition zone of the United States. Plants grow from bulbs that are 2 to 3 cm long, producing channeled leaves that are 3 to 8 mm in diameter. Leaves are characterized by their pale, whitish-green midrib (Goetz et al., 2003; McCarty et al., 2001). Bulbs produce lateral bulblets containing alkaloids poisonous to grazing animals (Facciola, 1990). In Tennessee, star-of-bethlehem begins to flower in early May and enters dormancy by early June (Main et al., 2004).
Star-of-bethlehem can invade open areas lacking plant competition (Haragan, 1991; Uva et al., 1997). Infestations have been reported on golf course fairways in Tennessee that have been associated with core aerification practices (Main et al., 2004). These star-of-bethlehem infestations negatively affect the aesthetic and functional quality of golf course fairways (Main et al., 2004).
Herbicides increasing the production of reactive oxygen species have shown activity against star-of-bethlehem. Bromoxynil is a member of the nitrile herbicide family that inhibits photosystem II by occupying the QB-binding domain on the D1 protein, inhibiting electron flow from photosystem II to...