Efficacy of Fluridone, Penoxsulam, and Bispyribac-sodium on Variable-leaf Milfoil

摘要

Variable-leaf milfoil (Myriophyllum heterophyllum Michx.) is a native perennial submersed plant ranging from southwestern Quebec and Ontario to North Dakota and southward to New Mexico and Florida (Godfrey and Wooten 1981). It is classified as a species of concern in Kentucky and is endangered in Ohio and Pennsylvania (USDA 2007). In the northeastern United States, however, variable-leaf milfoil is not native and is considered an invasive and weedy species. Variable-leaf milfoil is listed as invasive in states such as Connecticut and Maine, prohibited in Massachusetts and New Hampshire, and is a class A noxious weed in Vermont (NH-DES 2007, USDA 2007). As an invasive milfoil, it causes many of the same problems as Eurasian watermilfoil (Myriophyllum spicatum L.), including shading out native submersed vegetation and interfering with recreational activities and water supplies (NH-DES 2002, Halstead et al. 2003). Variable-leaf milfoil has been estimated to reduce lakefront property values by as much as 20 to 40 percent in New Hampshire (Hal-stead et al. 2003). Variable-leaf milfoil has been described as an aggressive invader that can grow up to one inch per day under optimal nutrient, temperature, and light conditions and spreads mainly via fragmentation (NH-DES 2002).