Gapway Swamp Giant Salvinia Management Project
Photos of Salvinia molesta in Richardson Pond (Cherry Grove, NC)
July 2020
The following 6 photos show areas adjacent to the dam. The first 5 photos provides an on-the-water perspective (via kayak). The last photo was taken from the top of the dam.... the lime-green area is the pond and the boat ramp is in the far left side of the image.
The following photos are of the two water-level-control structures at Richardson Pond. One structure is a flashboard riser and the other is a spillway. Giant Salvinia plants were being carried by water flow leading to downstream spread.
The following photos are of the far upstream reach of Richardson Pond. This bridge is along SR-1346 (Gapway Church Rd.). This area is ~300' downstream of the Buffkin Pond dam. This area was heavily infested with Giant Salvinia.
The following photos are of Buffkin Pond. Both photos were taken from the lower end of the pond, on the north side. The trees in the background of the first photo are growing on what remains of the dam; the dam failed (circa 1970's?). Giant Salvinia can be seen in the the forefront of the photo. The second photo shows the area adjacent to the dam. This photo was taken with a telephoto lens. This lower reach of Buffkin Pond (adjacent to the dam) is occupied, almost entirely, by floating mats of vegetation called tussocks.
March 26 2021
A dense mat of Giant Salvinia covers the pond. These photos were taken from the boat ramp, which is at the eastern end of the dam. The salvinia plants are in a winter dormancy. Frost has browned the uppermost layer of the mat. That layer has protected the plants below, which remain green and viable. The patches of green vegetation is Pennywort (Hydrocotyle spp.). Looking straight out from the boat ramp is a southwest direction.
June 16th 2021
The photos below were taken 4 weeks into a fluridone treatment. Fluridone is an herbicide that is used in aquatics. Herbicide products containing fluridone are typically used to perform in-water treatments vs. applying as a foliar spray. For this project a slow-release pellet formulation was applied. The objective was to achieve a target concentration (of fluridone in the water) and maintain that concentration throughout the growing season. Fluridone is slow-acting and works best by exposing the Giant Salvinia to a relatively low concentration (measured in ppb) for 90+ days. On this day, chlorosis and browning of target vegetation, was obvious from a distance.
June 29th 2021
The following photos were taken ~6 weeks into the fluridone treatment. This was also ~2 weeks after the second application of fluridone herbicide products. Chlorosis and browning of vegetation was obvious from a distance. A few close-up photos show the "bleaching effect" that fluridone causes. The hues of red seen in some of the photos is Alligatorweed that is being impacted by the fluridone. Alligatorweed is also recognized by NCDEQ as a noxious aquatic weed.
July 21st & 22nd 2021
The following photos were taken 9 weeks into a fluridone herbicide treatment. This was also 5 weeks after the second application of herbicide products. On this day wind had driven the floating vegetation up against the boat ramp. Condition of Salvinia plants can be seen at all stages here; from relatively healthy bright green, to hues of yellow, to brown, and black necrotic plant tissue that had not yet completely decayed. The floating mats of vegetation are primarily Giant Salvinia, and to a lesser extent, Alligatorweed, Water-spider Orchid, and Pennywort.
August 25th 2021
The following photos were taken 14 weeks into a fluridone treatment. This was also ~2 weeks after the 3rd application of herbicide products.
November 3rd 2021
The following photos show staff conducting Salvinia Weevil monitoring work. Salvinia Weevils are a biocontrol agent used to manage Giant Salvinia. Salvinia Weevils were released at Richardson Pond and at Buffkin Pond on 8/24/2021. These photos are of an area of Richardson Pond that was outside of the herbicide treatment. The floating mat of Giant Salvinia is ~6" thick and the vegetation is responding to autumnal conditions.
