Aquatic weed problems are common in the Panhandle of Florida. Common Salvinia (Salvinia minima) is a persistent invasive weed problem found in many ponds in Gadsden County. There are ten species of salvinia in the tropical Americas, but none are native to Florida. They are actually floating ferns that measure about 3/4 inch in length. Typically it is found in still waters that contain high organic matter. It can be found free-floating or in the mud. The leaves are round to somewhat broadly elliptic, (0.4–1 in long), with the upper surface having 4-pronged hairs, and the lower surface is hairy. It commonly occurs in freshwater ponds and swamps from the peninsula to the central panhandle of Florida.
Reproduction is by spores, or fragmentation of plants, allowing Salvinia to proliferate rapidly and become an aggressive invasive species. When these colonies cover the surface of a pond, as pictured above, they need to be controlled as the risk of oxygen depletion and fish kill is a possibility. If the pond is heavily infested with weeds, it may be possible (depending on the herbicide chosen) to treat the pond in sections and let each section decompose for about two weeks before treating another section. Aeration, particularly at night, for several days after treatment may help control the oxygen depletion.
Control measures include raking or seining, but remember that fragmentation can propagate the plant. Grass carp will consume salvinia, but are usually not effective for total control. Chemical control measures include :carfentrazone, diquat, fluridone, flumioxazin, glyphosate, imazamox, and penoxsulam. For recommendations for controlling Common Salvinia and other pond weeds, consult with your local Extension Agent.
For more information reference these UF/IFAS publications: