Hydrilla (Hydrilla verticillata L.f. Royle) is a submerged macrophyte introduced to Florida
in the 1950s and today infests over 50,000 ha of Florida's freshwater lake systems. This
species can fill the entire water column of these warm, shallow lakes, causing substantial
ecological and economic harm. Whole lake fluoridone treatments were the standard
practice in the 1990s until resistance was discovered in 2000, leaving management
programs with limited options. ProcellaCOR TM SC (active ingredient: Florpyrauxifen-
benzyl; SePRO Corp. Carmel, IN) is a new herbicide registered for aquatic use to control
hydrilla in Florida. Mesocosm studies proved this new active ingredient capable as a
selective, short exposure treatment effective on hydrilla. With this knowledge, we further
examined these attributes in an operational treatment, applied in August 2018, in a 50-
acre section of Fish lake (230 acres) at the maximum use rate of 5 prescription dose
units per acre-foot (48.3 µg ai L-1). Here, we report on biovolume reduction of hydrilla
extending over 200 days after treatment into late spring. We further report on the
selectivity and sensitivity by other native submersed and floating species at this high
rate.
