Support for the Fight Against Giant Salvinia Spreading

Just like Giant Salvinia, support for any and all efforts to fight this floating aquatic invasive plant is spreading. In a Saturday article from the Marshall News Messenger, additional funding from the Harrison County Commissioners Court was on the agenda for their Monday, September 8th meeting.

US Congressman Louie Gohmert who represents the area also provided his support for the efforts and need to continue them out at Caddo Lake. Not only did he encourage everyone to visit Caddo Lake and enjoy the lake's unique natural beauty, he also commended the efforts of the Center for Invasive Species Eradication's weevil rearing operation at the Caddo Lake National Wildlife Refuge and the work being done with the salvinia weevil. As the Congressman mentioned, the salvinia weevil does show promise for being able to manage giant salvinia levels in lake at some point in the future, but it will take time and a large number of weevils....both of which are in short supply. 

For now, research at the weevil rearing facility is focused on producing weevils and trying to identify a more cold tolerant strain of weevil that may be more able to withstand the sometime harsh winters that Caddo Lake can experience.

Congressman Gohmert takes a closer look at the salvinia weevil during an August 2012 visit to the weevil rearing facility at the Caddo Lake National Wildlife Refuge

In addition to support from elected officials, local support has greatly increased as well. People are volunteering time and resources to try and get a handle on the giant salvinia issue. Hopefully, weevil production capacity will increase through this increased interest and a step closer to managing giant salvinia can be taken.

Until then, keep up the good fight. And to borrow the "Take Care of Texas, It's the Only One We've Got" tag line from TCEQ and Kevin Fowler; Take Care of Caddo, It's the Only One We've Got"

Support for Weevils Grows...So does Giant Salvinia

This year has turned out to be a bad one for Caddo Lake in terms of giant salvinia coverage. Recent estimates have put the total number of acres covered in the Texas portion of the lake alone somewhere north of 6,000 acres. This level of infestation has drastically reduced use of the lake as boats easily get stuck in the floating mats of giant salvinia that cover the upper ends of the lake.

On a positive note, local support has grown significantly and the use of salvinia weevils is now viewed as the best, long term solution to the problem. In fact, the Greater Caddo Lake Association is hosting a benefit barbeque this Labor Day weekend that will expand the production capacity of weevils around Caddo Lake. An article in Sunday's Marshall News Messenger provides details of the event and further describes the dire situation at Caddo Lake this summer. If you can, please make plans to attend this great event and help support efforts to protect this beautiful lake.

Giant salvinia completely covers Boat Road C on Caddo Lake. Similar coverage of salvinia is present across more than 6,000 acres of Caddo Lake in Texas this summer.

Caddo Lake Giant Salvinia Control Program Updates

It has been a while since the last blog post, but rest assured that the fight against giant salvinia at Caddo Lake has been in high gear. With a relatively mild winter experienced this last year, giant salvinia levels on the lake coming into the spring were already nearing their highest levels in years. One positive of the mild winter was that weevil populations did survive the winter; however, higher water around the first of the year dispersed the remaining weevils widely across the lake.

Extensive giant salvinia coverage during May 2013 along boat road C near Joe Moore Hole

On the biological control front, one weevil release has been made from the Caddo Lake Salvinia Weevil Rearing Facility so far this year and a second release is being planned for the near future. An estimated 34,400 adult weevils were released along with an untold number of larvae and eggs. These weevils were released into backwater areas of the lake where they are least likely to be disturbed.

Weevil research has continued as well and is showing promising results:

- Small frame studies showed that salvinia weevils were able to reduce giant salvinia biomass by 50%

- A "Chill Coma Recovery Test" was conducted to evaluate salvinia weevils resuscitation time following an extended period freezing. Weevils from Australia resuscitated first followed by those from North Texas (Lewisville), South Louisiana (Houma) and from Florida. This suggests that weevils can adapt to localized weather conditions to some extent.

- "Solid Freeze Time Trials" were also conducted to evaluate the weevil's ability to tolerate weather extremes. Weevils were frozen solid for 24, 30 and 36 hours respectively and survival was documented. At 24 hours, survival was good for all weevils; however at 30 hours, Australian weevils survived far better than any weevils from the U.S. At 36 hours of freezing, weevil survival in all samples was greatly reduced.

- Efforts are also underway to collect weevils from higher elevations (cooler areas) in their native ranges in Argentina. Once received, their genetic make up will be evaluated and they will be subjected to "Chill Coma" and "Solid Freeze" tests to determine their ability to tolerate cold weather extremes.

The Problem Spreads

Earlier this week, an article in the Austin American Statesman revealed a growing problem in northeast Texas lakes....giant salvinia. According to Texas Parks and Wildlife Biologist Lynn Wright, lakes with recently reported giant salvinia infestations include Lake O’ The Pines, Gilmer, Murvaul, Wright Patman and Lake Welch.

This recent rash of infestations highlights the need to raise awareness about the dangers of this plant. It's rapid growth rate and lack of natural enemies in Texas give it a competitive advantage in almost any water body. Preventing new infestations is much easier than managing infestations once they arrive and as such TPWD is asking boaters to be extra vigilant about checking and cleaning their boats and trailers both before they launch and after they load.

 

To read the full article in the Statesman, click the link below.

http://www.statesman.com/news/sports/troublesome-plant-continues-to-spread-in-texas-lak/nWHkH/  

How Should Homeowners Deal with Salvinia?

In a recent article in the Marshall News Messenger titled "Before treating salvinia, residents must file paperwork", Tim Bister, Texas Parks and Wildlife Department's district supervisor and fisheries biologist in the Caddo Lake area discussed appropriate steps for homeowners and landowners around Caddo Lake to take if they want to fight giant salvinia on their own.

Caddo Lake is a public water body and as such, is managed by the state.  To deal with nuisance or invasive aquatic vegetation like that commonly present at Caddo Lake, the state requires that a document known as an Aquatic Vegetation Treatment proposal be filled out. What these documents do is outline the type of aquatic vegetation (floating, emergent or submerged), the target aquatic vegetation species name, the estimated amount of aquatic vegetation acreage to be treated, and the proposed treatment type (mechanical, biological or chemical). A map also accompanies these treatment proposals as well and helps TPWD ensure that there aren't any conflicting treatments planned.

While the article provides more specific information about Aquatic Vegetation Treatment proposals, it is always a good idea to contact the TPWD District office to discuss plans. In the Caddo Lake area, TPWD's District Office is located at 3802 East End Blvd. So., Marshall, Texas 75672. You can also contact them by phone at (903) 938-1007.

http://www.marshallnewsmessenger.com/news/before-treating-salvinia-residents-must-file-paperwork/article_50f99050-e992-55b3-bf62-409eab8f50de.html

Cautiously Optimistic About Progress

Through the summer and into the fall salvinia weevils were released by the Center for Invasive Species Eradication team and local volunteers in the upper portions of Caddo Lake where giant salvinia had firmly established itself.  While results were not dramatic, optimism is building that weevils are having an impact on giant salvinia. Lee Eisenberg described this small success in a recent article in the Marshall News Messenger.

http://www.marshallnewsmessenger.com/news/researcher-cautiously-optimistic-weevil-is-eating-salvinia/article_c8d23f7a-87c7-5751-9ae0-b33abd6c4cc3.html

Efforts will continue in the spring with the release of additional weevils into the back water areas of the lake in hopes of weevil populations expanding enough to yield visible results.

Lee Eisenberg wades through damaged salvinia in September 2012. The browning of the salvinia indicates that it is not a healthy plant and is in the process of dying.

Interagency Giant Salvinia Control Team Meeting Highlights

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.