ERDC/TN APCRP-BC-19, Effect of Dried Mycoleptodiscus terrestris Inoculums on Fluridone-Susceptible and Fluridone-Resistant Hydrilla Biotypes

INTRODUCTION: Hydrilla verticillata (L.f.) Royle, a member of the Hydrocharitaceae, was introduced into Florida in the 1950’s (Schmitz et al. 1991). The introduction was the dioecious biotype with only gynoecious plants making up the original infestation. Today hydrilla has invaded at least 21 states either as dioecious or monoecious biotypes or both (Richardson 2008). Called “the perfect aquatic weed” by Langeland (1996), the plant has several characteristics that make it an excellent competitor in freshwater systems. It has low light and carbon dioxide compensation points (Van et al. 1976) and it reproduces by several means including fragmentation, stolons, and turions that develop in leaf axils or subterraneously from rhizomes (Langeland 1996). Seeds have been reported in monoecious hydrilla populations (Langeland and Smith 1984) but are in all likelihood not a major reproductive mechanism.