Management of Aquatic Weeds

Abstract

Plants growing in aquatic environments can have positive impacts, such as producing dissolved oxygen and absorbing toxins. However, they are usually regarded as a nuisance and therefore labeled as “weeds.” Prevention is a much more reliable approach than trying to treat them after they are established. Proper pond construction (providing adequate water depth), fertilization (to promote phytoplankton rather than macrophytes), aquatic dye application (to block out sunlight), manual harvest as the weeds appear, stocking grass carp (eat the weeds) or koi (create water turbidity), and water drawdowns (stranding weeds along the shore) can be effective preventive measures. Once the weeds are present, however, controlling them with herbicides is usually the most effective recourse. Algae are typically controlled with copper sulfate or copper-based complexes, while higher aquatic plants/weeds are controlled by properly selected herbicides that include bispyribac-sodium, carfentrazone-ethyl, diquat dibromide, endothall compounds, flumioxazin, fluridone, 2,4-D, glyphosate, imazamox, imazapyr, triclopyr, penoxsulam, sodium carbonate peroxyhydrate, and nutrient reducers.