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Oregon's war on weeds helps save agriculture and natural resources
Photo of distribution of biological control agents in tansy ragwort field. 
ODA began using biocontrol in the 70s for tansy ragwort.
Governor proclaims Oregon Invasive Weed Awareness Week
Governor Kitzhaber has proclaimed May 20-26 as Oregon Invasive Weed Awareness Week, signifying the importance of the state's long battle with noxious weeds. The week provides another opportunity to educate Oregonians about the value of invasive weed detection and control efforts in protecting natural resources and agricultural production.

"Currently, there are 117 state listed noxious weeds that we and our partners are working to contain and/or control to protect our natural resources," says Tim Butler, supervisor of the Oregon Department of Agriculture's Noxious Weed Control Program. "Noxious weeds challenge Oregon's environment, natural resources, and agricultural economy through negative impacts."

The problem of weeds goes far beyond dandelions and other common undesirable plants in lawns and gardens. The plants that make the so called "A" and "B" list of noxious weeds in Oregon could cause havoc in many ways. 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.

Invasive weeds are a major concern to Oregon agriculture, with its farmgate value of $5.1 billion. Successfully managing noxious weeds is critical to maintaining and improving sustainability.

"The cost of controlling weeds effect the bottom line and highly invasive populations can permanently degrade and render lands unusable," says Butler. "Indirect impacts by weeds to agriculture-such as impairing water quality, affecting stream flows, and contributing to erosion- have a lasting effect on our resources that affect the industry. Maintaining environmental health and a healthy agriculture industry are directly tied to effective weed management programs and cooperative efforts."

More directly, noxious weeds negatively impact crop and forage production through competition for space, water, and nutrients. Noxious weeds can contaminate and decrease seed and hay quality, often leading to quarantines that impact trade and sales. It's estimated that about $30 billion is attributed annually to losses in crops, pasture, and forest productivity in the US because of noxious weeds.

ODA's Noxious Weed Control Program evolved out of statewide efforts in the mid 1970s to deal withtansy ragwort, a toxic weed that was taking over many pastures and poisoning horses and cattle. Livestock owners collectively faced $4.2 million a year in livestock losses because of tansy. That's when the Oregon Legislature allocated funds to deal with the problem. Through pioneering biological control efforts- using insects that were natural enemies of tansy ragwort- the "scourge of the seventies" was eventually brought under control.

There are more recent cases of controlling invasive weeds specifically tied to Oregon agriculture:
  • Paterson's curse was first detected in Linn County in 2003. In 2004, a second infestation was confirmed on a Douglas County hillside pasture. The weed, toxic to livestock, is a serious invader in Australia. A rapid response effort was implemented to avert the potential impact in Oregon. As with tansy, Paterson's curse could result in serious livestock losses. A partnership including Roseburg Forest Products and the Cow Creek Band of Umpqua Tribe contributed funds for the project. Douglas County Soil and Water Conservation District provided contracted labor and ODA supervised the project. The infestations have been contained.
  • Small broomrape, also known as clover broomrape, is a parasitic federal and state listed noxious weed first detected in Clackamas County red clover seed production in 1999. The initial field was quarantined and the crop destroyed in order to protect the ability to export red clover seed out of the state. Intensive surveys over the next two years found more infested fields. ODA worked closely with the industry, Oregon State University, and USDA-APHIS to come up with some viable solutions. OSU conducted research on effective control methodology and provided red clover growers effective best management practices for control of small broomrape. USDA-APHIS conducted an evaluation of seed cleaning procedures and provided effective cleaning protocols for red clover seed growers. Today, the industry needs to continue diligence in educating growers about surveying for and detecting small broomrape if it present in their field so they can implement OSU control protocols since cleaning alone may not keep small broomrape seed out of red clover seed lots.
  • Italian thistle, also known as slender flower thistle, was a major problem on Douglas County hillside pastures during the 1980s where it often out-competed desirable forage and excluded livestock. ODA released three biological control agents that had a dramatic positive effect on bringing Italian thistle under control.
  • On Oregon's eastern flank, county programs, federal agencies, cooperative weed management areas, farmers, and ranchers are controlling skeletonweed to prevent its spread from Idaho. This a challenge with some 3.5 million acres of skeletonweed in northern and southwest Idaho, and another 2 million acres in Washington. The defense includes an integrated management strategy of biological control and chemical treatments.

Butler stresses the importance of having a full slate of cooperators- from county weed control districts and cooperative weed management areas to such federal partners as the US Forest Service and the Bureau of Land Management. That list includes private farmers, ranchers, and all Oregonians.

"If we can find these new invader weeds early before they become significant problems, that's what we are striving for," says Butler. "The ag community can be very active in letting us know if they find new weeds. They can also help keep existing weed populations from spreading. Standard practice in the industry involves cleaning combines and equipment, so that farmers aren't moving weeds from field to field."

This year's theme for Oregon Invasive Weed Awareness Week is "Report and Remove Invasive Plants", a good message for all Oregonians all year long. Noxious weeds can be reported to the Invasive Species Hotline at 1-866-INVADER or by ODA's Weedmapper.

For more information, contact Tim Butler at (503) 986-4625.

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