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| Oregon still a leader in biological control of noxious weeds | ||
| 05/14/2008 | ||
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May 18-24 proclaimed Invasive Weed Awareness Week Once thought of as just agriculture's problem, the issue of invasive noxious weeds has spilled over into Oregon's natural environment, threatening native plants and established ecosystems. That has triggered a heightened public awareness and a realization that the problem of noxious weeds touches all Oregonians. Invasive Weed Awareness Week, May 18-24 as proclaimed by Governor Kulongoski, strongly suggests that all Oregonians can be a part of the solution. Meanwhile, the Oregon Department of Agriculture continues to be a national leader in using biological control agents against unwanted plant species- essentially using good bugs to fight bad weeds. It is conservatively estimated that the annual damage caused by noxious weeds in Oregon is in excess of $100 million. Early detection and rapid response is the most effective strategy to keep introductions of invasive weeds from fully establishing. When a noxious weed is in abundance and Oregonians have to learn to live with it, ODA considers biocontrol whenever possible. The combination of strategies has kept invasive noxious weeds from becoming an even greater threat to Oregon. "The increase in trade and travel has brought more invasive species to Oregon," says Tim Butler, supervisor of ODA's Noxious Weed Control Program. "But it's a battle worth fighting to protect Oregon's agricultural economy and natural resources as a whole. The governor's proclamation shows the state's commitment to address noxious weeds." Part of the battle plan involves public education and outreach. Mention the problem of weeds and most Oregonians probably think of dandelions and other common undesirable plants in lawns and gardens. However, the kind of plants that make the so called "A" and "B" list of noxious weeds in Oregon could have extreme impacts to the state's natural resources as well as the economy. Some of these plants may look pretty, but have nasty characteristics- reproducing prolifically and crowding out desirable native plant species. In some cases, they can change an entire habitat important to wildlife. "We have worked for years to educate the public and heighten the awareness of why invasive noxious weeds are bad," says Butler. "By looking at the interest level today, I think we've achieved some success. More and more groups are involved in weed management programs. We are moving in the right direction, but we still have a long way to go. Funding and resources are limiting factors. That's why we have to prioritize our noxious weed species and target those where we feel we can make a difference." The public can best help by reporting new invasive weed species. The Invasive Species Hotline (1-866-INVADER) is a good place to pass along information. But for weeds firmly entrenched with no chance of eradication, biocontrol is one of the few hopes for keeping the invasive species in check. No other state has had the kind of success enjoyed by Oregon when it comes to the use of biocontrol on noxious weeds. To date, ODA has used 71 biocontrol agents against 31 weed species. About one out of every three has proven successful. Positive results range from the battle against tansy ragwort in the 1980s to the more recent success stories involving purple loosestrife and diffuse knapweed. "Once a noxious weed becomes so widespread and abundant that other methods of control are either too costly or prohibitive, the program turns to biological control," says ODA entomologist Eric Coombs. "For every dollar spent in our biocontrol program, the public gets back about $15 in benefits due to the impact of reuniting a noxious weed with its natural enemies." Biocontrol agents, once they are strategically released into targeted, weed-infested areas, are allowed to grow in population to the point where the good bugs are in surplus. They are then harvested and deployed to other locations to battle the target weed. The process can take from three to five years. ODA has found varying degrees of success using biocontrol on established noxious weeds. A stem weevil that attacks Dalmatian toadflax has reduced the weed by up to 99 percent in some sites. "We are now emphasizing the harvest of the weevil so it can be redistributed throughout Eastern Oregon in Klamath County, and the areas near the John Day and Snake river systems," says Coombs. There also continues to be good success with Larinus minutus, a seed head weevil and arch enemy of diffuse knapweed. In some areas near Heppner and The Dalles, the weed is now almost non-existent. ODA has at least a decade of good results from a quartet of insects working on purple loosestrife. But the leaf-eating beetle Gallerucella has had the greatest success. Most of the Baskett Slough National Wildlife Refuge west of Salem has been reclaimed from the showy noxious weed thanks to the beetle's effectiveness. Biocontrol agents have been enlisted the past few years in the war against Scotch broom, which is so well established in Oregon that even control efforts seem daunting. ODA's success rate is mixed at best. "We've used a seed weevil that is now in high numbers, but research shows there must be 95 percent of the Scotch broom seeds controlled in order to make an impact on the weed's population," says Coombs. "A few years ago, we added a seed beetle as a complimentary agent. Last year was the first time that beetle was at decent enough numbers to be collected and redistributed. My prediction is that in 50 years, Scotch broom won't be the problem it is now, because of our biological control efforts." On the horizon are biocontrol agents to control gorse and knotweed, among other targeted weeds. Meanwhile, ODA emphasizes the need for good land management to promote the growth of natural vegetation. Relying only on biocontrol could lead to replacing one weed for another. Invasive Weed Awareness Week in Oregon should bring more attention to the fight against noxious weeds. But it will continue taking a variety of efforts 52 weeks a year to truly make a difference. For more information, contact Tim Butler or Eric Coombs at (503) 986-4621. Story of the Week pdf version http://oregon.gov/ODA/docs/pdf/news/080514weeds.pdf Audio Story of the Week http://oregon.gov/ODA/news/080514weeds_audio.shtml |
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