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ODA and partners turn giant hogweed into smaller problem
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7/14/2010
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Article Content Progress is being made in Portland and other sites
An invasive noxious weed in Oregon that poses both environmental and human health impacts is still around, but local, state, and federal efforts to control and eradicate giant hogweed appear to be working. This is the time of year the plant's flowers are blooming. The last thing Oregon needs is for the plants to produce more seeds. So, in addition to treating known infested sites, weed control officials would like to know about any new sightings of giant hogweed.
"Our initial focus is on the known sites and to bring them under control, but we are actively surveying for new sites as well," says Tim Butler, supervisor of the Oregon Department of Agriculture's Noxious Weed Control Program.
Since its discovery in Oregon in 2001, giant hogweed has been found statewide at 120 sites located in 10 counties from Lane County north. Many sites have been in the Portland area. Currently, 82 sites remain active. But that means 38 sites have been eradicated of the invasive species through a combination of digging up plants, cutting and bagging its seed heads, and herbicide application, The progress is measured more by the number of plants at each site rather than the number of sites.
"In 2001, we had locations where there were as many as a thousand plants per site," says ODA's Shannon Brubaker, special projects coordinator with the Noxious Weed Program. "Now, many of these same sites have just a couple of plants coming back each year or they have no plants at all. We need five years of zero plant count to declare a site eradicated of giant hogweed. So each year with zero plants is one year closer to eradication at that site."
Giant hogweed can spread into riparian areas and outcompete native plant species. But it is also a public health hazard. Its watery sap can cause photo-dermatitis. Sap on a person's skin and exposed to sunlight can cause painful blisters and scarring. Contact with eyes can cause temporary or even permanent blindness. Homeowners are advised not to try and treat the noxious weed themselves unless they use extreme caution and wear protective clothing. It's better to report the plant to weed control officials. Giant hogweed is often mistaken for other members of the carrot family, most commonly cow parsnip. But hogweed grows much taller- as high as 15-feet- and has tell-tale bumps on its stem. Oregonians can go online for information on how to distinguish giant hogweed from lookalikes.
Native to Eurasia, giant hogweed was introduced into North America originally as a novelty plant for gardeners. Now, it carries both state and federal designations as a noxious weed. Its introduction to Oregon appears to have been intentional.
"We think it was intentionally planted as an ornamental at some point," says Butler. "People in the Portland area where it has been found have told us they didn't realize the plant was a problem, and simply thought it was attractive because it grows so large and is showy-looking. That's probably how a lot of it has been moved around."
Progress in the battle against giant hogweed is made possible through partnerships. The U.S. Department of Agriculture's Animal Plant Health Inspection Service has provided grant money for survey work. Local partners have taken an active role in control and eradication efforts. The City of Portland's Early Detection and Rapid Response (EDRR) program is a prime example.
"Our group has been treating hogweed for the last two years," says Mitch Bixby, a botanic specialist with the city's Bureau of Environmental Services. "Since hogweed is not only an ODA target species, but also a city-wide ‘required eradication' species, it makes sense for us to work together. Primarily, city staff is assisting ODA staff in the field- navigating, giving neighborhood context, and researching property ownership. But we also monitor recent treatment, watch for new sites, map old sites, and get occasional permits-of-entry. These all dovetail nicely into our existing program. Plus, it's nice to have the weight of ODA behind us."
Bixby has not experienced dealing with noxious weed control outside of an urban setting, but he can see how unique the challenges might be in the city.
"For one thing, there are so many properties in a small space that even relatively small infestations require working with and getting access from multiple landowners," says Bixby. "Also, these properties are often fenced or hedged in. So finding the extent of a patch, or finding the patch at all, can take a lot of effort."
On a positive note, cities also offer unusual opportunities for fighting weeds.
"There is a whole range of organizations- walking clubs and neighborhood associations- that make very effective allies," says Bixby. "Strategic outreach to these groups, combined with effective networking, help us to decentralize our efforts and increase our survey capacity. Also, when one group plugs into the discussion, suddenly the discussion moves off in all directions. Marketing people once called this ‘buzz', and it's one fun thing about doing weed work in an urban setting."
The buzz about giant hogweed is helping change some attitudes about the showy plant turned bad weed.
"The mentality has changed since 2001," says ODA's Brubaker. "Landowners used to say they like the plant and did not want it removed. Now they say they want the plant gone and would like our help. They understand more about the threat giant hogweed poses to our watersheds and to public health."
Proactive efforts to detect giant hogweed early and eradicate when possible has kept the invasive plant from becoming a giant problem in Oregon. Progress is being made, but now is no time to ease up the vigilance.
For more information, contact Tim Butler or Shannon Brubaker at ODA at (503) 986-4621 or Mitch Bixby, City of Portland EDRR, at (503) 823-2989.
Story of the Week pdf version
http://oregon.gov/ODA/docs/pdf/news/100714hogweed.pdf
Audio Story of the Week
http://oregon.gov/ODA/news/100714hogweed_audio.shtml
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