LAKE COUNTY – Dalmation toadflax. Skeletonweed. Hydrilla.
No, they're not characters from a Harry Potter novel, but for agriculture officials they can be just as scary.
They're invasive weed species – both terrestrial and aquatic – that have made themselves right at home in Lake County. In the process, they've disrupted local species and, in the case of hydrilla, cost the state Department of Food & Agriculture millions in an eradication effort.
This week is Invasive Weed Awareness Week, which will include a public meeting this evening at 6 p.m. in the Board of Supervisors chambers in Lakeport (see “How you can get involved”) and a driving tour of the county on Thursday to point out weed species and eradication efforts.
Invasive weed species arrive in a new area through a manner of avenues, including traveling in water, coming by air as thistles do, in animal fir and in hay or seed, said county Deputy Agriculture Commissioner Chuck Morse. Travel from farther distances usually results from human involvement, whether intentional or not.
When it comes to aquatic weeks, hydrilla is probably the best known. Food and Agriculture has given the weed an “A” rating because it's so pernicious, said Morse.
A-rated weeds like hydrilla warrant help from the state. Food and Agriculture Jay Van Rein said in recent years the agency has spent $2 million annually in its statewide battle against hydrilla.
“Over the last several years we've had about 20 infestations in about 10 counties,” said Van Rein, who didn't have the specific breakdown of how much money has been spent just in Lake County.
The governor declared an emergency in the mid-1980s because of hydrilla, said Van Rein. Since then, Food and Agriculture, the state's Boating and Waterways division, federal agencies such as the Army Corps of Engineers and the Bureau of Reclamation, and local agriculture and public works departments have joined forces to eradicate hydrilla.
The infestation on Clear Lake was discovered Aug. 1, 1994, during a routine inspection survey conducted by Food and Agriculture and the county agricultural commissioner's office, said Van Rein. Treatment started within days.
Clear Lake was the largest body of water where hydrilla was found, said Van Rein, and because of the lake's size the potential for impacts was high.
Initially, the infestation was between 175 and 200 infested surface acres throughout the lake's upper arm, said Van Rein. By 2001, that had grown to 1,150 surface acres of the lake presumed infested.
However, the number of plants had already peaked by that point, with the largest number – 210 – found in 1997 and going steadily downhill from there, said Van Rein, thanks to a variety of control methods including small-scale dredging, hand removal, biocontrol and registered aquatic herbicides.
Van Rein said hydrilla is now mostly controlled in Lake County. “It is still infested, but it's at a fairly low level.”
In the last three years, a total of only three plants have been found in all of Clear Lake.
“That's pretty amazing progress,” said Van Rein.
Especially considering what a tough weed it is to eradicate. Van Rein said it reproduces easily and can become both a water supply and water quality issue, and can be a nuisance for dam operators. “This thing is nobody's friend.”
The battle on land
Morse said the county agriculture department focuses on the state's A- and B-rated weeds, which require certain enforcement actions. He said he is working on about 14 such weeds.
They include Scotch thistle, Dalmatian toadflax, plumesless thistle and the recently found skeleton weed, all of which affect agricultural environments and are extremely hard to eradicate, said Morse. Luckily, he added, these more pernicious weeds don't have large populations locally.
B-rated weeds in Morse's sites are purple star thistle – “like yellow star thistle on steroids,” he said – as well as artichoke thistle, perennial pepper weed and dyer's woad.
In the 2005-06 fiscal year, Morse said the county spent $7,000 from its general fund on weed eradication, in addition to grants used to fund the program.
One place where they've been successful is attacking the population of Arundo donax, the false bamboo often seen growing along the lakeshore.
Morse said they took Arundo donax on because they believed they could control it, and because of Clear Lake's location at the top of the Cache Creek watershed. That effort also is being supported through grant funding through Food & Agriculture, even though it only has a C rating.
“We're making really great progress,” said Morse.
They've had a tougher time with oblong spurge, a B-rated pest that has infested a large area from Buckingham to Anderson Road off Point Lakeview.
It became completely unmanageable, said Morse, and with expensive treatments not working, the agriculture department stopped the treatments.
Morse said it's important for landowners to keep a watch for invasive weeds, because early action is one of the most effective control methods.
Early treatment combined with ongoing and consistent followup and monitoring is the best strategy for success, he added.
The county's weed management area is now applying for grant funding to help expand its efforts to include other invasive species like Scotch broom.
How you can get involved
Go to the meeting
A public meeting on invasive weed species will be held at 6 p.m. today, Wednesday, July 18, in the Board of Supervisors chambers at the courthouse in Lakeport.
Deputy Water Resources Director Pam Francis will discuss the zebra mussel and hydrilla, as well as other invasive water plants, algae an viruses and offer a question and answer session.
Deputy Agricultural Commissioner Chuck Morse will discuss terrestrial weeds including yellow star thistle – “everyone's favorite weed to hate”– Arundo donax, salt cedar, tree of heaven, perennial pepper weed, brooms, Italian thistle, bull thistle, fullers teasel, Himalayan blackberry, Goatshead and more. A question and answer session will follow.
Take the tour
The Lake County Weed Management Area will lead an invasive weed tour on Thursday, July 19, beginning in Lakeport and proceeding to Nice, Rodman Slough, Main Street Bridge in Kelseyville, ending in Lakeside Park as their final “weed” stop and barbecue lunch.
Participants will see a demonstration areas where invasive weeds have been successfully controlled through a variety of methods.
Registration begins at 8:15 a.m. at Lake County Department of Agriculture’s parking lot (883 Lakeport Blvd.). The tour will leave from the parking lot at 8:45 a.m. and end by 11:30 a.m. at Lakeside Park. Please RSVP at 263-0217 if you plan to attend.
While the end-of-tour lunch is free of charge, a donation to offset the costs of the lunch and refreshments would be appreciated.
Keep your eyes open
Morse said the public has an important part to play in controlling invasive weeds.
If you see something unusual, contact the county agriculture department and get it identified, he suggested.
“If it's an unusual native that's not an issue, water it and nurture it,” he said.
But if it's something that doesn't belong here and can hurt the local environment, eradicate it immediately.
For more information call the Lake County Agriculture Department, 263-0217.
E-mail Elizabeth Larson at
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