Dubose Declares War on Salvinia
Oliver “Jackson” Schrumpf
Special To The Record
Precinct 3 County Commissioner John Dubose has declared war on Salvinia. No, it’s not a state in Western Europe near Bosnia-Herzegovina. It is the aquatic plant that grows exponentially and, unless controlled, covers whole waterways, spreading by clinging to boats, and eventually, causes oxygen depletion in the water, leading to fish kills.
Dubose was alerted to the problem this fall when large outbreaks of salvinia occurred in several areas of Orange County, including Adam’s Bayou, Clark’s Channel, Old Channel of Cow Bayou and several areas of Cow Bayou in the vicinity of Bridge City.
Dubose sought the assistance of Texas Parks and Wildlife Department. A plan was developed to perform an aerial photographic survey to assess the extent of the problem. Consideration was given to contracting for aerial application of herbicides. But several delays occurred in carrying out the aerial survey. And many questions arose about the use of herbicides. Would the herbicides kill fish? Would they effect foliage not intended to be killed? Can an appropriate herbicide be found that will kill the Salvinia? Is aerial application of herbicides economically feasible? Complicating the problem was that the Salvinia infestations are not static. They float. They move with the wind and tides, and they can sink below the surface of the water. They can be one or two feet thick.
Dubose is still pushing for an aerial survey to locate all areas affected in the County.
Research revealed that the U.S. Department of Agriculture and Corps of Engineers had already done the heavy lifting and had a solution waiting in the wings: Biocontrol.
Salvinia is a floating fern. Giant Salvinia (Salvinia molesta) is native to South America. It is considered an invasive weed in warm climates. It is a prohibited Federal noxious weed. It cannot be legally imported, but unfortunately it is already growing uncontrolled in many North American warmer climates, including Texas, Louisiana, and other Gulf states and Hawaii. It grows rapidly and forms dense mats over still waters. It’s only currently known economic use is as a floating decoration in aquariums. Salvinia’s small, oval leaves form dense mats—green, yellow-green, or brown—that can easily double in size in just a few days. Sometimes two feet thick or more, the mats can cover the surface of an entire pond or small lake, blocking out sunlight that other plants need. And the mats use up oxygen that fish, insects, and other aquatic dwellers require.
Giant salvinia is a bother to humans as well. It ruins conditions for fishing, boating and waterskiing. The weed also clogs irrigation and electrical generating systems. Salvinia is already blamed for closing off large areas of the water in Lake Bistineau near Doyline in Webster Parish, La. and the Caney Lakes Recreation Area near Minden, La. Salvinia grows aggressively and multiplies quickly without natural controls.
So what is the magic bullet that will control this invasive weed threatening our bayous and waterways? A tiny weevil, Cyrtobagous salviniae, has been used successfully to control giant salvinia and its smaller cousins. The helpful insect has already been used—with great success—in more than 13 countries over 3 continents. The native South American beetle is only one-tenth of an inch long. Yet the beetles have a documented success rate. When the weevils were used in Lake Moondarra in Australia, they destroyed more than 8,000 tons of giant salvinia in less than a year.
Is there a downside? Will the weevils start eating rice crops when they run out of Salvinia? Tests already completed provided additional evidence that the weevils attack only salvinia and won’t pester other plants.
So where do we go from here?
John Dubose is in contact with Julie Nachtrieb, at the Lewisville Aquatic Ecosystem Research Facility, in Lewisville, Texas, who is working on the problem as part of the Aquatic Plant Control Research program. In mid October, Julie reported she had a colony of weevils ready for release that are used to control salvinia. She said the weevils are completely host specific (i.e., feed ONLY on salvinia and not other vegetation), and have been found to be very successful at controlling salvinia. In the past, due to a grant from USDA-APHIS, the cost of releasing the beetles in multiple locations in multiple states was minimal, but the current federal budget for this program is unclear.
However, Ms. Nachtrieb indicates that a final solution may require an integrated approach using both biocontrols (such as the beetles) and herbicides. In September and October, the salvinia infestation covered all of Clark’s Channel (west of Highway 87, south of Cow Bayou), but too little was known about the solution at that time: Who had authority to take action?; Should poison be used? Which poison? How should poison be applied? Is there an alternative? What area of Orange County is in greatest need? How much will it cost to treat all the waterways that need treatment? Now research has answered many of these questions, but the current infestation has dwindled, sunk, or floated out to sea so that only patches remain where they can be seen. These patches are an eyesore and a potential problem for fishermen, boaters, and skiers, and they will balloon again in the spring.
The problem is that the fast-growing aquatic weed is far ahead of the efforts to control it. If the weevils are released early in the spring (as soon as temperatures stabilize around 70 degrees) they can reproduce every three to four weeks. Getting enough weevils out, early enough, is one of the logistical problems which must be solved in order to BEGIN to attack the festering problem.
One thing is sure, in the battle for control of our waterways, Salvinia has the jump on us.
But an answer is in the wings. And the issue now is, will we sit back and watch our waterways get covered with one or two feet of useless plantlife? Or will we counter-attack?
If you are interested in this issue, or for more information on this subject please see http://salvinia.org/Docs/guidance_Feb2010.pdf ].
If John Dubose has his way, and with cooperation from all the other agencies involved, we will be spring-loaded to release the counter attack in the spring.
Oliver “Jackson” Schrumpf
Sulphur, La. and Bridge City, Texas