Laboratory response of monoecious Hydrilla to four slow-acting, enzyme-inhibiting herbicides

摘要

The submersed, invasive plant hydrilla {Hydrilla verticillata (L. f.) Royle] has been described as "the perfect aquatic weed" (Langeland 1996), and it often requires management via use of registered aquatic herbicides and/or grass carp (Haller 2014).There are two genetically different biotypes of hydrilla found in the United States (dioecious and monoecious). Within the United States, the biology, phenology, and invasion range for these plants are distinct (McFarland and Barko 1987, Van 1989, Madeira et al. 1997, Madeira et al. 2004, and Benoit 2011). The monoecious biotype is found mainly in the northern-tier states (including North Carolina and Tennessee), spreading southward into Georgia and Alabama and northward toward Canada, whereas the dioecious biotype is found primarily in southern-tier states (U.S. Geological Survey 2016). The continued spread of monoecious hydrilla (M. hydrilla) into northern waters of the United States is of significant concern to resource managers (Netherland and Greer 2014). A recent literature review indicated that, of 1,246 articles on hydrilla, only 53 specifically mentioned the monoecious biotype (True-Meadows et al. 2016). The disparity in the published literature between the dioecious and monoecious hydrilla biotypes includes studies on ecology, plant biology, and management information, including the response to herbicides.Prior herbicide research conducted on M. hydrilla has been limited to only 3 of the 15 registered aquatic herbicides: diquat, endothall (Van and Steward 1986, Van et al. 1987, Poovey and Getsinger 2010), and fluridone (Nawrocki 2011, Netherland 2015). Bensulfuron-methyl has also been studied (Van and Vandiver 1992), but that chemistry is not registered for aquatic use.