On October 16th, 2012 the Interagency Giant Salvinia Control Team convened in Karnack at the community center to discuss recent research findings, speak of control successes and plan for the future. Representative from the Caddo Lake Institute, Cypress Valley Navigation District, Louisiana Department of Wildlife and Fisheries, Louisiana State University Ag Center, Northwestern State University, Texas A&M AgriLife Research and Extension, Texas Parks and Wildlife Department, Texas Water Resources Institute's Center for Invasive Species Eradication, U.S. Army Corps of Engineers, and U.S. Fish and Wildlife Service personnel all spoke of efforts underway to combat giant salvinia biologically and chemically.
Biological control using the salvinia weevil (Crytobagous salviniae) garnered the bulk of discussion. LSU Ag Center, Texas A&M AgriLife, Texas Parks and Wildlife and the U.S. Army Corps of Engineers are all working to mass produce and research the salvinia weevil and each had progress/success to report as well as planned research to discuss.
Some brief highlights from these groups include:
- effective giant salvinia control is being seen in several location including southern Louisiana and B.A. Steinhagen Lake near Jasper, TX.
- cold tolerance studies revealed significant differences in weevils from Texas, Louisiana, Florida and Australia to tolerate extended freezing
- chemical toxicity trial show that neither chemical nor surfactants commonly used to treat giant salvinia are toxic to the salvinia weevil
- chemical trials reveal effectiveness of chemical/surfactant combinations, but none tested are 100% mortal to giant salvinia
Ongoing and planned work includes:
- evaluate what factors cause weevils to take flight; assess how well they can fly and what distance they can cover
- work to import weevils from colder climates such as the Argentinian highlands or southern Brazil
- evaluate combined biological and chemical treatments and evaluate control success
- test impacts of aerial chemical applications in winter through dormant tree canopy
Collectively, the meeting was filled with positives and all parties involved were optimistic about the progress being made. With fair weather and time, the salvinia weevils seem to be well on their way to making a significant dent in giant salvinia infestations. The threat of cold temperatures loom though, and more work to identify strains of the weevil that can tolerate these colder temperatures and begin reproducing earlier in the spring are critical to the successful use of weevils in areas like Caddo Lake that experience periodically cold winters.