LAKE COUNTY — Another 10 hydrilla plants were spotted in Clear Lake over the past several days by agricultural technicians out looking for the invasive weed as part of the California Department of Agriculture”s (CDFA) hydrilla eradication program for Clear Lake. That brings the total count of hydrilla found this year to 28, most of those finds being in Soda Bay.
Patrick Akers, CDFA”s supervising scientist for the hydrilla project, said while the prolific aquatic plant is in several water bodies throughout the state, Clear Lake is one of the CDFA”s biggest projects.
“We were expecting hydrilla to reappear after we stopped treating,” said Akers in a Wednesday interview with the Record-Bee. “We didn”t know how much, but were expecting it to come back. That”s part of the reality of this plant.”
The CDFA has battled the hydrilla plant on Clear Lake since 1994. Akers explained that the herbicide fluridone, known by the trade name Sonar, has been used to combat the weed since 1996 in conjunction with a copper compound called Komeen. Since then, 2006 was the first time CDFA stopped applying the herbicide in order to determine if the eradication effort was effective.
“Hydrilla can look like it”s gone for a long time, and once the control pressure is off they can come back,” said Akers, adding that the CDFA bumped its crew up 50 percent this year in anticipation of just that.
The plant sprouts from tubers, which are potato-like seeds the size of navy beans. Akers said they can sit dormant in the sediment on the bottom of a water body for five to seven years waiting for ideal conditions to sprout into plants.
And once they do, they can double their biomass in a week to 10 days under ideal conditions, Akers explained.
Akers said while the weed has taken over water bodies stretching from Virginia to Florida across the southern U.S. including parts of Texas and Indiana, California is the only state that tries to eradicate the weed. It forms large mats that can take up 90 to 100 percent of a lake”s surface, growing from an average depth of 30 feet, cutting off sunlight for other aquatic plants and sucking enough oxygen to create problems for freshwater fish.
“We”re kind of running a big experiment here,” said Akers of the CDFA”s eradication efforts. “We don”t have a lot of experience to draw on from other places to see how the game will play out with this plant.” Akers added that the plant has reduced water delivery in the Imperial Irrigation District by 85 percent.
Florida spends roughly $30 million a year just controlling the weed, not eradicating it, said Akers. CDFA spends about $800,000 a year, which Akers said could go up by as much as $400,000 depending on how much Sonar is used. “We”re probably going to put out 300 40-pound pales of Sonar, and they”re about $800 per pale. Right there that”s $240,000 of Sonar.”
Approximately 150 acres on Clear Lake will get the treatment, and will continue to get the same treatment for at least the next three years.
“We take it very seriously about controlling the plants as young as we can possibly get them,” said Akers, adding that in prime conditions the plants can produce new tubers in three weeks.
Akers said September is the time the plant usually starts producing tubers, although the particular type found in Clear Lake ? monoecious, a biotype of the hydrilla verticillata ? can produce tubers any time of the year.
Prime conditions for the plant to grow are when the water is above 50 degrees Fahrenheit, lots of sun and plenty of nutrients.
“The thing about Clear Lake is it”s so murky that down at the bottom of the lake there”s not a lot of sunlight, so it doesn”t grow as fast,” said Akers, adding that he”s not convinced the plants agricultural technicians have been finding could make new tubers in three weeks. Still, he said, he knows they”re getting close.
Contact Tiffany Revelle at trevelle@record-bee.com. Contact Tiffany Revelle at trevelle@record-bee.com. To comment on this story or any others, look at the end of this story for “Comments,” fill in the web form, and the click “Publish”
