We are doing a trial of eleven aquatic herbicides for their potential to control Brazilian waterweed (Egeria densa). The active ingredients being tested are bispyribac sodium, carfentrazone, copper-ethylenediamine complex, diquat, dipotassium salt of endothall, the dimethylalkylamine salt of endothall, florpyrauxifen-benzyl, flumioxazin, fluridone, imazamox, and penoxsulam. The study is a twelve-week static exposure of a single initial treatment, using all of the 50 tanks in the mesocosm facility. While not all of these aquatic herbicides would be allowed in the Sacramento/San Joaquin River Delta, we should at least know what might be useable in other habitats near the Delta. Currently, California State Parks Division of Boating and Waterways relies entirely on fluridone for managing Brazilian waterweed, but other active ingredients need to be considered for control across the spectrum of sites in the Delta.

Prepared by John Madsen, USDA. This project is conducted in cooperation with the Delta Region Areawide Aquatic Weed Program (DRAAWP).