Herbicide spraying begins at Lake Wilson
By Zenaida Serrano Espanol
Advertiser Staff Writer
The state Department of Agriculture is stepping up its attack against Lake Wilson's Salvinia molesta, beginning herbicide application today — a supplement to the excavation effort — following two days of testing.
Richard Ambo • The Honolulu Advertiser
"Spraying the herbicide Rodeo is one of the most critical components of this whole (cleanup)" of the noxious weed, said Peter Young, director of the state Department of Land and Natural Resources.
John Lopez watches the Salvinia molesta removal operation at Lake Wilson from his fifth-floor unit in the Kemo'o By The Lake condominium in Wahiawa.
About two weeks ago, workers from DLNR's Aquatic Resources Division began spraying areas on a small scale with a 20-gallon spray unit, Young said. But the agriculture department will increase efforts with a 100-gallon gas engine sprayer.
Sprayings on Friday and yesterday acted as somewhat of a test run, said Larry Nakahara, plant pest control manager of the agriculture department.
With a 26-foot motorboat and a 100-gallon spray unit, agriculture workers yesterday mainly wanted to calibrate the equipment, Nakahara said, "so that we can measure the amount of herbicide that we're putting out so that we're not putting out too little or too much. (Today) we'll be doing the full-on treatment."
The Rodeo herbicide, also known as AquaMaster, is labeled for aquatic weed control. The herbicide moves through the plant from the point of foliage contact into the root system, eventually killing the plant.
"It's a nonrestrictive pesticide, so in other words you could wear a long-sleeve shirt, pants and you don't need a mask," Nakahara said. "So it's a very safe pesticide."
In addition to AquaMaster, workers will likely use another herbicide called Diquat, said Lyle Wong, administrator for the Plant Industry Division of the agriculture department.
"Of the commercial herbicides tested by the (U.S. Army) Corps of Engineers that are approved for use for aquatic weed control by the U.S. Environmental Protection Agency, these were the two that were the most effective," Wong said.
The sprayings will be "high volume for good coverage, low pressure so that we're not airborning the spray," Wong said.
"We're going to (spray) every day except weekends," Nakahara said.
Richard Ambo • The Honolulu Advertiser
The weekend clean-up hold worries area residents like John Lopez, who has been concerned with the rapid spread of the noxious weed. It can produce as much as 400 tons of new growth per day.
Efforts to eradicate Salvinia molesta from Lake Wilson in Wahiawa will be stepped up today as agriculture department workers begin spraying the noxious weed with herbicides. Test sprayings were done Friday and yesterday in small areas.
"What they cleaned this morning, it's already covered," said Lopez, who lives on the fifth floor of the Kemo'o By The Lake condominium. "I'm looking outside right now, and I see no spots," where the weed is gone and the water shows through, he said yesterday.
Nakahara said it's hard to say whether the salvinia growth has increased in the past few days.
"You cannot just look at it and say there's an increase, because salvinia has a tendency to move with the wind," Nakahara said. "So if it's a windy day, it'll bunch up in a corner."
Officials plan to add more clean-up sites to battle the weed. The active site right now is the city and county site, Young said, behind Kemo'o By The Lake condominium on Wilikina Drive.
"We're mobilizing (today) and should be in operation (tomorrow), the second of the excavation sites, and that will be the state site," Young said. "And we're discussing with the military when they will open their site, which will be a third site."
The second site will be near the boat ramp at the Lake Wilson Recreation Area. Officials are still discussing the location for a third excavation site and when work will begin there.
The state also hopes to add an airboat and operator to its spray arsenal. The decision is pending word from the U.S. Army Corps of Engineers in Florida, which will supply the boat and operator.
"The concern that we have is that in areas where the mat is very thick, it's going to be hard to push the boat through," Wong said. "Airboats, like they have in Florida, those swamp buggies, these things can glide right over."
Reach Zenaida Serrano Espanol at zespanol@honoluluadvertiser.com or 535-8174.
