LAKE COUNTY — As the California Department of Food and Agriculture (CDFA) moves forward with efforts to eradicate hydrilla found recently in Clear Lake, two agents will be used to combat the invasive aquatic weed.
The first is a copper-based herbicide used to kill, or “burn off” the plants found by CDFA agricultural technicians, whose numbers have doubled this year in anticipation of the recent hydrilla finds after it stopped treatments that have been ongoing since 1996 in an effort to gague how effective the treatment has been.
It goes by the trade name Komeen, and photos taken of recent treatments make it appear to be a big purple bruise on the waters of Clear Lake from a distance for about an hour after it”s applied.
CDFA scientist Patrick Akers explained that the copper is only used once in an area where hydrilla is found because it is an element that does not break down but goes away by dilution.
Known by the trade name Komeen, the copper-based herbicide kills hydrilla on contact by disrupting its cells, Akers explained. “The copper gets rid of competing vegetation that would suck up the Sonar, so there”s more of it there to kill little plants as they come out,” said Akers.
Sonar is the trade name for fluridone, which is dispersed four to six days after a Komeen treatment as pellets. The pellets settle in the sediment layer on the lake bottom, where hydrilla tubers can lay in wait for five to seven years for the right conditions to sprout into new plants, Akers said.
“The way this particular (herbicide) works is it interferes with the ability of the plant to make orange pigment, or the pigment that protects chlorophyll from ultraviolet rays,” Akers explained. Without the ultraviolet protection from orange pigment, any new hydrilla plant rearing its head out of the sediment would break down and die. Akers said the Sonar pellets stay effective for about a year, making ongoing treatment necessary.
The CDFA typically treats for three years and then takes a break to see how effective the treatment has been. “We”ve made a lot of progress on Clear Lake with hydrill, and I wnt to continue to keep it under control,” said Akers, noting that Hydrilla can spread until it covers most if not all of a water body.
California is the only state that tries to eradicate the weed, said Akers, and of several water bodies in the state, Clear Lake is the CDFA”s biggest project.
He noted Clear Lake looks to be in a good trend. At the peak treatment period for hydrilla on Clear Lake around 2002, Akers said the CDFA cleared 1,200 acres. With several recent finds, most of them in Soda Bay, he said the CDFA plans to treat a total of 150 acres.
CDFA Agricultural Technician Russ Huber noted that a recently delayed shipment of Komeen arrived Wednesday, and treatment is due to continue in Soda Bay today.
Complicating the CDFA”s detection efforts are other, native aquatic plants like sago weed, which can be found in mats towrd the west end of the lake, said Akers. Since hydrilla can grow from a greater depth than other plants, it can come from underneath and become entangled.
Generally it chokes out the light and sucks a carbon ion from the water called carbonate, changing the water”s PH in a way that isn”t beneficial for the other plants. It can also lower oxygen levels to below what fish can tolerate, said Akers.
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