| Section four: noxious weed control |
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| Introduction |
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Our mission is to protect Oregon’s natural resources from the invasion and proliferation of exotic noxious weeds. The Noxious Weed Control Section does this by
- providing leadership and coordinating noxious weed management.
- serving as a technical resource for noxious weed issues.
- providing public outreach, education, and awareness.
- conducting weed risk assessments.
- detecting new invaders and implementing rapid response control projects.
- coordinating and implementing biological control of weeds.
- administering the State Weed Board Grant Program.
From left to right rear: Ken French, Tom Forney
Middle: Eric Coombs, Dave Langland
Front: Glenn Miller, Jo Davis, Beth Meyers, Bonnie Rasmussen, Bob Barrett, Tim Butler, Dan Sharratt (staff includes Shannon Brubaker, not pictured).
The following is an overview of the Noxious Weed Control Program and a brief summary of major activities for 2006.
The Noxious Weed Control Program has 12 technical staff located in Salem, Canyonville, Klamath Falls, Redmond, Burns, and Union. The program also employs seasonal staff during the field season to assist in the implementation of noxious weed control projects statewide.
The Noxious Weed Control Program provides statewide leadership for coordination and management of state listed noxious weeds. The state program focuses on early detection and rapid response projects for new invasive noxious weeds, implements biological control, implements statewide inventory and survey, assists the public and cooperators through technology transfer and noxious weed education, maintains noxious weed data, and provides assistance to land managers and cooperators with integrated weed management projects. The Noxious Weed Control Program also supports the Oregon State Weed Board with administration of the OSWB Grant Program, develops statewide management objectives, develops weed risk assessments,and maintains the State Noxious Weed List.
Noxious weeds do not respect ownership and watershed boundaries; effective management requires support and participation from all affected parties. Cooperative management of noxious weeds allows for prioritizing activities and the best use of limited resources to meet the challenging needs of noxious weed management. Partnerships allow management across jurisdictional and ownership boundaries. For these reasons, we seek to increase communication, improve coordination, gain cooperation, and assist planning and implementation of projects among cooperators. The State Noxious Weed Control Program encourages and supports partnerships between private landowners, state agencies, federal agencies, tribal governments, counties, weed management areas, watershed groups, conservation organizations, and other weed control entities in the state.
The Oregon State Weed Board (OSWB) is a seven-member board appointed by the director of the Oregon Department of Agriculture. The primary mission of the OSWB is to guide statewide noxious weed control priorities and to award noxious weed control funds. Priorities are developed in part through the state noxious weed control policy and classification system by listing and prioritizing noxious weeds.
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| 2006 weed program highlights |
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- During 2006 the Noxious Weed Control Program implemented 135 projects. There were 672 noxious weed treatments made by staff using integrated control. Of these, 569 sites were treated with herbicides and 91 sites were treated either manually or by mechanical methods. There were 419 treatments made on federal lands, and 253 treatments on private, county or state lands.
- Biological agents were released at more than 100 sites in Oregon during 2006. Over 146 biocontrol sites were monitored to determine establishment and impact of biocontrol agents. Eighty-eight releases of various bio agents were collected during 2006 and made available to cooperators in the region. Pre-treatment or post-treatment monitoring was done at 220 sites.
- OSWB grants: Reviewing noxious weed control grants and submitting recommendations to the Oregon State Weed Board for approval and monitoring of awarded grants were key accomplishments once again in 2006. The OSWB received 51 grant proposals in 2006.
- Blackberry rust, Phragmidium violaceum: in spring 2005, an exotic pathogen that attacks Himalayan blackberry was detected in Curry and Coos counties by ODA staff and follow-up monitoring was done in 2006.
- Giant hogweed, Heracleum mantegazzianum: Five new sites were found in the 2006 season, most occurring in the north Willamette Valley near Portland.
- Kudzu, Pueraria lobata, was identified for the first time in Oregon in 2000; follow-up monitoring for possible re-growth was done in 2006.
- Meadow hawkweed: During 2006, treatment of the Lolo Pass hawkweed site continued. Hawkweed was also a point of interest in Central Oregon. A Bend area nursery was found to be selling orange hawkweed in 2005 and follow-up treatment was done in 2006.
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| 2006 noxious weed list update |
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An important function of the Noxious Weed Control Program is identifying new invasive weed species before they become firmly established in Oregon. Plant risk assessments are tools that assist in the listing of new species by gathering background information. Priority activities include networking with weed professionals worldwide, identifying the highest risk species, and conducting yearly surveys to detect new populations as they occur.
Not all recently recognized invasive species are new to North America. Certain ornamental species that have been planted for years are now raising concerns because of their invasive nature. Species that have come to the forefront include English ivy, pampas grass, and butterfly bush. Discussions between ODA, State Weed Board, and the nursery industry are essential so that solutions acceptable to interested groups can be attained.
Noxious weeds are defined by the Oregon State Weed Board as exotic, non-indigenous plant species that are injurious to public health, agriculture, recreation, wildlife, public or private property. As of February 2006, there were 104 species of state-listed noxious weeds in Oregon.
Below, lists the changes made to the State Noxious Weed List in February 2006:
- Jubata grass, Cortaderia jubata, was listed as a “B” rated weed.
- Paterson’s curse, Echium plantagineum, was added to the “T” list.
- Knotweed complex, Polygonum, was added to the “T” list.
Two weeds were removed from the State Noxious Weed List in February 2006:- Wild proso millet, Panicum miliaceum
- Short-fringed knapweed, Centaurea nigrescens
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| Noxious weed control grants |
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The Oregon State Weed Board (OSWB) received approximately $1.3 million of Measure 66 Lottery Funds for noxious weed control grants, during the 2005-2007 biennium. Priority projects were those that restore, enhance, or protect fish and wildlife habitat and watershed function. There continues to be a substantial amount of time allocated by Noxious Weed Control Program staff in the review, administration, and monitoring of the Noxious Weed Grant Program. Two cycles for the biennium were completed in 2006. Fifty-one grants were awarded by the OSWB, totaling $660,105.
Chart: OSWB grants applied and approved
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| Summary of early detection and treatment activities |
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Annual treatments for the control of “A” (highest priority) and “T” (target) designated weeds have reduced the net acreage of many large weed populations. Annual intensive control efforts for distaff thistle, Carthamus lanatus, and purple/Iberian starthistle, Centaurea calitrapa, C. iberica, have achieved 99 percent control on most sites. Douglas County contains most known distaff thistle sites; one site is known from Josephine County. Purple/Iberian starthistle is found only in Clackamas County and is fully contained. Purple/Iberian starthistle has the potential to invade 1.5 million acres in Oregon, which equates to a potential economic impact of $12 million per year.
Early detection and rapid response (EDRR) is a primary activity of the ODA program. ODA approaches EDRR by working with cooperators and developing partnerships to identify species of concern, distribute information, and implement projects. A primary activity is utilizing a risk assessment process with the Oregon State Weed Board to list species on the State Noxious Weed List as “A,” “B,” or “T.” Priority listed species are incorporated into presentation and outreach activities to cooperators and the general public. Surveys for early detection are conducted; pest alerts and other information are produced and distributed to increase awareness in an effort to find and report infestations. Rapid response projects are implemented to eradicate or contain new invaders. An economic analysis reveals a 33:1 benefit to cost ratio for projects of this type.
ODA continues to meet program goals to limit or reduce acreages of all “A” rated weeds and implement project for “A” and “T” listed species. Statewide management plans for “T” weeds are updated each January to identify priorities for the field staff as new problems arise. Weed awareness and weed site reductions continue to be achieved through public education, implementation of chemical control and containment projects, and biological control projects targeting susceptible weed species. The following are a few highlights of “A” and “T” weed projects for 2006.
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| Distaff thistle |
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In 1987, wooly distaff thistle was discovered in Oregon. The potential danger to Oregon’s native plant communities, forage production, and watershed health was made evident by California’s and Australia’s experiences where huge acreages were dominated by the thistle. Control was initiated in Oregon in 1987. Four new sites were found in 2004, two in 2005, one in 2006. Now 37 ownerships, are known to be infested in 19 locations in Douglas County, one in Josephine County, and one in Curry County.
This project involves the control, survey and monitoring of all known infestations of distaff thistle. An annual thistle, all distaff sites are being intensively treated, with total elimination of distaff thistle the goal. Each site is worked two to three times each season, with crews using herbicides, backpack sprayers and manual methods. Hard seed germinating each fall are the source of each season’s infestation. Plant counts show reductions of well over 90 percent from historic levels. It is important to continue to protect Oregon’s riparian areas and watershed health from further invasion by this non-native thistle.
ODA will continue to provide supervision and coordination for this project, involving but not limited to, landowner contacts, treatment schedules, mixing and application of herbicides, pre- and post- treatment monitoring, survey, public education, etc. Contract labor totaling 1,400-1,600 man hours and a lead worker are both supplied by Douglas Soil and Water Conservation District through funding from an Oregon State Weed Board Grant.
- Treatment 2006: 6.9 net acres of distaff thistle were treated on over 3,655 gross acres.
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| Patterson's curse |
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Ken French spraying for Patterson’s curse in Douglas County.
Paterson’s curse, Echium plantagineum, was first detected in August of 2003 in Linn County. In 2004 a second infestation was confirmed on hillside pasture in Douglas County. Paterson’s curse is originally from Western Europe and the Mediterranean region; it is widespread in temperate zones and extends into the tropics. In Australia it has become a serious weed of grazed pastures, grain production areas and natural areas. Paterson’s curse is a prolific seeder and can germinate under a broad range of environmental conditions.
Delimiting surveys were completed for the project area in central Linn County in 2003 and additional survey was done at the new site location in Douglas County during 2004 to determine the distribution and spread of the population. The Linn County population is limited to four locations on field borders in the Lebanon area. These sites were regularly monitored in 2006 and a number of new plants that emmerged were treated.
In May 2004, a large infestation consisting of 100 net acres/300 gross acres of Paterson’s curse was identified southeast of Dillard in Douglas County. Meetings were held with landowners and neighbors. Eighty net acres of the project area were sprayed by a helicopter in 2004, with 20 net acres of additional ground treatment. All 2005 treatment were done by ground application, with most areas requiring five treatment sessions for complete control and to prevent seeding. In 2006, the heaviest 100 acres were treated by ODA staff, using a Polaris RTV with a 50 gallon sprayer and 18 foot folding booms and foam marker. This proved to be much more effective than spot treating. Roseburg Forest Products supplied the herbicide for treating their lands. Two spot treatments were made during the summer with contract crews, to clean up any missed plants. The Cow Creek Band of Umpqua Tribe of Indians and ODA contributed funds for the contract labor, while Douglas County Soil and Water Conservation District helped with contract administration.
- Treatment 2006: 102.8 net acres were treated over 310 gross acres
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| Central Oregon orange hawkweed |
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In September 2005, a new detection of orange hawkweed, Hieracium aurantiacum, a state “A” listed noxious weed, was found being sold at a nursery in Deschutes County. Oregon Department of Agriculture staff confiscated and destroyed 157 orange hawkweed plants. ODA staff worked with the nursery, was very cooperative in resolving the issue. Program staff developed and distributed a noxious weed alert sheet on orange hawkweed and distributed it to cooperators through our weed list serves and through a letter and mailing to all the nursery producers and retailers throughout Oregon. There was also a newspaper article in the Bend paper that generated 16 calls from private landowners who thought that they could have orange hawkweed in their ornamental plantings. All sites were followed up on in 2006 by ODA staff and both manual and chemical control was used. Also in 2006, two new sites were detected in ornamental plantings in Harney and Union counties. Sites will be monitored and treated as necessary in 2007.
- Treatment 2006: 4.75 gross acres; 0.44 net acres
orange hawkweed noxious weed alert (pdf, 645 KB)
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| Barbed goatgrass |
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Barbed goatgrass, an “A” rated weed, was detected along Highway 199 near Rough and Ready Creek, south of Cave Junction in June of 2003. The site was treated but it was late and the plants were mature. Fewer plants were observed in 2005, than in 2004. Bridge construction started in May 2005 with major soil disturbance. In 2006 plant numbers were greatly reduced, with the only active infestation found outside the construction zone. The infestation was chemically treated in spring 2006 and any remaining plants were hand pulled and bagged in early summer 2006. No plants produced seed in 2006.
- Treatment 2006: 252 plants were found and treated using both chemical and manual control.
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| Yellow floating heart |
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Yellow floating heart, Nymphoides peltata, is an ornamental pond plant. The first wild population was reported in 2004 in a pond adjacent to Fanno Creek in Washington County and was listed as an “A” weed by the OSWB in 2005. The Washington County site was treated in late summer. Fall monitoring showed re-growth and indicated a need for additional treatment in 2006. A second site was detected in 2005 near Springfield in Lane County. In 2006 both sites received treatment and sites will be monitored during 2007.
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| Giant hogweed |
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Giant hogweed, Heracleum mantegazzianum, is an Oregon state “A” listed noxious weed, a federal listed noxious weed and is on the Western Region CAPS Pest List. Hogweed is a human health concern; the sap is highly toxic and causes phytophotodermatitis. This noxious weed is also invasive in natural areas and can be a pest in agricultural and recreation areas. At risk habitats include wetland margins, riparian zones, deciduous and mixed conifer woodlands, agriculture production margins, recreation areas and residences. Giant hogweed was first detected in Oregon in 2001 and, since then, an early detection and control project has been implemented in Northwestern Oregon in an effort to reduce public health risks and prevent widespread establishment in the state.
Weed control staff treating giant hogweed in Portland Metro area.
Hogweed surveys are conducted in the field by staff as well as through mail and phone queries of property owners with known infestations. Hogweed control is done primarily by property owners with ODA staff assisting with high priority sites. Small infestations of giant hogweed respond well to both mechanical and chemical treatments. Once a site has no giant hogweed reported for five consecutive years, it is verified by staff and considered eradicated at that location.
Chart: Net acres giant hogweed in Oregon
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| Kudzu |
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In July 2000, kudzu, Pueraria lobata, was detected on a road bank in Clackamas County. This was the first infestation detected west of Texas. Kudzu is an aggressive climbing vine that smothers other plants. It is a native of China and Japan and is a major problem in the southeastern US where an estimated seven million acres are infested. In August 2000, the second kudzu site for Oregon was detected in Multnomah County, and in June 2001, a third site was detected in Multnomah County. All sites were initially treated with the selective herbicide clopyralid, which is very effective for kudzu control.
Survey and detection efforts were conducted throughout Western Oregon during 2006 and no new sites were detected. All three known sites were monitored throughout the 2006 season and all sites will be monitored in 2007.
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| Plumeless thistle |
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Plumeless thistle, Cirsium acanthoides, a state listed “A” weed was known to exist only at one site in Fox Valley (Grant County) prior to 2004. In 2004, new sites were found prompting ODA to take a lead in the project. As a result of these expanded infestations, ODA staff undertook an intensive survey of much of Fox Valley and alerted landowners of the expanding population. Plumeless thistle was found and treated on 0.8 acres scattered over 1,200 acres in the south end of Fox Valley and four very small populations in the north valley on five private ranch properties. John George, Grant County Weed Control, and ODA attempted to regain the upper hand in the battle with Plumeless thistle in Grant County in 2004. Some 50 acres were treated on six ownerships. John left the program in late fall of 2004 and Shannon Springer took over. In 2005, Grant County made the spring treatment at all of the sites treated in 2004. ODA joined with Grant County to cover the affected area when the plants were easily identifiable. The 2004 treatment was very effective, with rosette numbers being markedly reduced. Treated acreage was not reduced much because the thistle rosettes were scattered and mixed with other thistles in many sites. Landowner interest and cooperation is high in Fox Valley with many of the new sites coming from local ranchers. Grant County Weed Control supervisor, Tom Rush, and his summer crew, surveyed and treated the infested area during the 2006 season. ODA staff assisted on two of the larger ownerships. Thistle treatments were combined with Mediterranean sage treatment at three of the ownerships. Treatment efficacy appears to be good.
- 2006 Treatment: 10 net acres / 1,200 gross acres
- Surveyed: 4,000 acres
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| Squarrose knapweed |
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Squarrose knapweed, Centaurea virgata, a state listed “A” weed, has been found at five locations in Oregon in the past. The largest site is near Long Creek in Grant County, in good quality bunchgrass range on three private ranches. This site has been under intensive treatment since the late 1980s to contain the spread and reduce the infestation. During the 2005 field season the containment area was intensively surveyed to find and treat existing plants. The 2004 treatment was very successful yielding a reduction from 15 acres treated in 2004 to three acres in 2005. Grant County weed supervisor, Tom Rush, with funding from an Oregon State Weed Board grant, performed the summer survey under ODA direction, treating plants as they were found. ODA will continue to take the lead on the squarrose knapweed project in the future.
- 2006 Treatment: 3 acres Net/ 700 acres gross
- Surveyed: 1,200 acres
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| Matgrass treatment project |
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Matgrass, Nardus stricta, is a state listed “A” weed and occurs at only one known site in Oregon. It is a bunch type, low growing perennial grass that is not palatable for grazing by cattle, horses, elk, or other animals. Matgrass starts growing early in the spring before most other pasture grasses and sets seed early in June in the Fort Klamath area at the foot of Crater Lake. Matgrass seedlings are very hard to see amongst other pasture grasses, as their crowns will range from the size of a dime to the size of a quarter. Seedlings have very fine leaf blades that are only about one to two inches tall and the seedlings will set seed in their first growing season. Matgrass seeds are thrown from the mature seed head several inches making a colony of plants, roughly circular in shape, and from one to three feet in diameter, in just one or two years. Second year plants usually are two or three inches in diameter and often with some brown leaves at the center of the crown. Spotting the second year plants is somewhat easier although still difficult if the other pasture grasses are growing.
Matgrass was first noticed in a peat pasture about 35 years ago by the landowner. The matgrass was not noticed until there were established colonies several feet in diameter, which were not grazed by cattle on the pasture. The infestation is located approximately one mile west of Fort Klamath, Oregon, and is the only matgrass known to occur in Oregon. It has been speculated that the matgrass seed was brought to the site by a migratory bird from Siberia or Scandinavia where it is native. The farming practices of dragging the pastures to break up cattle manure clumps in the early spring and flood irrigation have moved the matgrass plants across 180 acres of pasture.
Control efforts on the matgrass infestations were begun about 33 years ago by the landowner. About 20 years ago, Klamath County Noxious Weed Control personnel began to help the landowner treat the matgrass and continue treatment efforts for the next 10 years. During the last 13 years, the Oregon Department of Agriculture has joined the effort to eliminate or contain the matgrass infestation.
Eradication of the matgrass infestation is probably not possible unless the grasses on the entire pasture area were eliminated for the life of the matgrass seed in the soil seed bank. At this time there does not appear to be an alternate cropping program to take the pasture out of grass production. Containment of the matgrass infestation to the one pasture has been successful to date, as no other infestations have been found in the area. Infestation levels of matgrass have varied from year to year depending on how many plants were missed when treating the area. The matgrass infestation level in the pasture has been declining since the owner has discontinued dragging the field and delayed flood irrigation until after treatment has been finished.
In 2006, ODA crews treated the matgrass using ATVs carrying chemical tanks with powered handguns as was done in previous years. Matgrass treatment was made by walking over each site multiple times, and spraying all plants found using glyphosate and a marker dye. The entire pasture was surveyed to find any plants that may have spread into previously clean areas.
- 2006 Treatment: 4.1 net acres / 95 gross acres
- Surveyed: 180 acres
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| Special projects for 2006 |
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The weed control program works on a variety of special projects and with a host of public and private cooperators to implement noxious weed control projects around the state. The following are a few of the projects completed in 2006:
Blackberry rust monitoring
In spring 2005, an exotic pathogen that attacks Himalayan blackberry was detected in Curry and Coos counties by ODA weed specialist Ken French. After consultation with state and federal pathologists, the pathogen was identified as Phragmidium violaceum. This is the rust that has been used in Australia and Chile as a biological control agent for wild infestations of blackberries (Rubus fruticosus group). Earlier this year, the pathogen was also detected in New Zealand, where it arrived as an unapproved adventive natural enemy. In Oregon, it has been found to occur on two species of blackberry, Himalayan (Rubus procerus, = R. armeniacus, = R. discolor) and on a thornless variety of evergreen blackberry (R. laciniatus). No one knows how the rust arrived in Oregon, or when, but it is suspected to have been around for at least two years. The rust has been found in all western counties of Oregon except Jackson and Josephine. It has been found in Washington as far north as the Canadian border and over 300 miles south of the Oregon border in California. The rust can cause die-back on blackberries and severely reduce fruit set. Affected vines have shriveled leaves covered on the underside with orange rust pustules that rain a yellowish-orange powder when disturbed. During 2006, the rust was monitored and even though the rust was found in most areas it did not make significant impacts on wild blackberry infestations in most areas. The lack of impact in 2006 is presumably thought to be due to climatic conditions that were not favorable to the rust. The rust will continue to be monitored during the 2007 season. The full economic and ecological impacts are not yet known. Scientists at OSU are working with caneberry producers to find fungicides to help protect the evergreen blackberry crop. No adverse effects of the rust were reported in 2006. This pathogen is not an approved agent for biological control of blackberry and it should not be moved around because of the risk to native Rubus and crop species. In Australia, susceptible varieties of the weedy blackberry were reduced 50 percent after several years of exposure to the rust fungus. However, resistant varieties required the introduction of additional strains of the rust to provide additional control. USDA-ARS is looking at identification of other isolates of the rust that may be approved for release if determined that they are safe to non-target Rubus species.
WeedMapper project
WeedMapper (www.weedmapper.org) is a Web site that provides distribution maps of all state-listed weeds in Oregon as well as information on the identification and impacts of those weeds. It also provides a weed sighting report form to allow land managers to notify ODA of a new weed sighting. Weeds are mapped at the state and county levels. The Web site is a joint project of the Oregon Department of Agriculture and Oregon State University with support from BLM, USFS and many data contributors.
Weed maps are shown at two different resolutions. When GPS or township, range and section data is available, maps at the state and county level are produced with each weed location pinpointed. General state distribution maps are also displayed that show the abundance of a weed by county based on the knowledge of Noxious Weed Control Program staff.
Data is accepted from many different cooperators. WeedMapper maps are compiled with data from ODA, USFS, BLM, county weed programs, SWCDs, cities and non-profit groups, such as weed working groups. Data is also accepted from the weed sighting report form located on the Web site after it is reviewed for completeness and reliability.
After the Web site is updated, the distribution data is forwarded to OSU for use in modeling weed spread to help target areas for surveying and prioritize prevention activities.
2006 accomplishments
Data contributed to WeedMapper increased greatly in 2006, due to extensive outreach efforts. In 2005, 17 agencies contributed data to WeedMapper, in 2006 there were 41. Data was processed and displayed with updated GIS software, allowing for more efficient transition from raw data to mapped data as well as producing maps that are clearer and easier to view.
WeedMapper is a valuable tool in early detection and rapid response efforts. Review of data shared by agencies has turned up two instances of high-priority “A” weeds that were unknown in the area. The Web site has also been used to verify the identification of “A” weeds and has prompted users to call the Invasive Species Hotline which is listed in conjunction with all information about these high-priority weeds.
A function was added in response to user requests that allows users to sort maps by county. Reports from users continue to be overwhelmingly positive. The Web site is being used by a wide range of people including land managers from federal, state and local agencies, property owners and students. Preliminary usage reports from OSU indicate that the Web site is viewed an average of 250 times a day.
WeedMapper data was used in 2006 to model the spread of yellow starthistle, perennial pepperweed and gorse.
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| Biological control |
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Since 1947, 71 species of classical biological control agents have been introduced against 27 species of noxious weeds. Several of these biocontrol agents have become reassociated with six additional species of weeds for which they were not originally introduced. The Oregon Department of Agriculture manages 112 biocontrol projects (weed/agent combinations), the most of any state in the US. The ODA biocontrol database contains more than 11,500 records of biocontrol agent releases. Several biocontrol projects have been successful in controlling targeted weeds, including tansy ragwort, St. Johnswort, musk thistle, Mediterranean sage, purple loosestrife, yellow starthistle, and diffuse knapweed, especially at sites that are managed to improve competitive vegetation. ODA strives to adhere to the International Code of Best Practices for classical biological control of weeds in order to better implement a safer and more effective biocontrol program.
Chart: Cumulative number of weeds targeted (gray) and cumulative number of classical biological control agents (dark) released in Oregon by year.
New releases and recoveries
Dalmatian toadflax
The toadflax moth, Calophasia lunula, was discovered in Oregon at several sites in the Hells Canyon area. The moth originated from populations in Idaho and Washington. However, it has not been demonstrated as a very effective agent in other states.
Field bindweed
The field bindweed gall mite, Aceria malherbae, was found established in Oregon for the first time. A healthy population of mites was recovered in the Tygh Valley area in Wasco County. Some redistribution efforts were made in the local site in order to provide a larger nursery site for redistribution to other areas in the state in 2007.
Salt cedar
The leaf beetle, Diorhabda elongata, was released in 2003 for the first time in Oregon. Three additional releases were made in Malheur County in August of 2005, after meeting extensive pre-monitoring requirements set by US Fish and Wildlife Service. In 2006, Gary Brown, USDA-APHIS, provided ODA over 10,000 adult beetles from Lovelock, Nevada, which were released at several sites in Malheur County. Ant predation appears to be affecting establishment of this agent. Additional collections in Nevada are planned for 2007, along with more intensive surveys being coordinated with BLM.
Scotch broom
The Scotch broom gall mite, Aceria genistae, was discovered near Portland, Oregon. This was the first finding of this adventive natural enemy of Scotch broom in the US. It was later found to be established in several areas around Tacoma, Washington. ODA is cooperating with Jennifer Andreas, WSU, to conduct host specificity studies to determine if the mite is safe enough for redistribution into new areas.
Significant accomplishments
Biological agents were released at more than 100 sites in Oregon during 2006. Over 100 biocontrol sites were monitored to determine establishment and impact of biocontrol agents. The USDA APHIS-PPQ (APHIS) biocontrol program, under the direction of Gary Brown, remains a very important partner in implementing biocontrol in Oregon. ODA and APHIS typically supply surplus biocontrol agents to many local agencies and other states. The ODA program continues to work on cooperative research projects with Dr. Jeff Miller and Dr. Peter McEvoy and their staff at Oregon State University. The ODA biocontrol program also serves as the state level biological control of weeds data center for the US.
Dalmatian toadflax
The stem-boring weevil, Mecinus janthinus, is emerging as a very promising biocontrol agent which drastically reduced toadflax density in several counties in Oregon in 2005 and 2006. Collection for redistribution in Oregon began in 2006 and will continue for several years.
Knotweed
Prerelease studies on Japanese knotweed and its allies were conducted at several sites in Oregon in cooperation with ODA. These studies are necessary before any new agents can be released in Oregon. A new quarantine facility, the first in Oregon, was opened at Oregon State University Forestry Sciences, which will be used to conduct host specificity studies for prospective biocontrol agents. The project is being coordinated by Dr. Fritzi Grevstad and primarily funded by USFS, with ODA as a major partner. Prospective biocontrol agents are expected to arrive in quarantine in early 2007.
Mediterranean sage
An ongoing cooperative study with Dr. Jeff Miller, OSU Department of Range Science, is studying the regional long-term impacts of the root/crown weevil Phrydiuchus tau. Most ODA release sites from 1970-1983 have shown significant control, especially at sites now dominated by perennial grasses and shrubs. Results from regional studies will be submitted for publication in 2007.
Purple loosestrife
The Galerucella leaf beetles have reduced numerous infestations of purple loosestrife throughout Oregon by more than 90 percent. Cooperative biocontrol projects continued with APHIS staff, Dr. Ralph Garono, Earth Designs Inc., and Dr. Peter McEvoy of OSU, to monitor and redistribute the biocontrol agents throughout the lower tidal zones of the Columbia River area. Many purple loosestrife stands are declining following severe defoliation by the leaf beetles.
Tansy ragwort
In 2005, numerous sites in the Willamette Valley experienced a resurgence of tansy ragwort, especially in Marion County. Biocontrol agents were found at all of the recalcitrant infestations. Fewer ragwort rosettes were observed during fall of 2006 (less than 10 percent of the density of the 2005 outbreak) therefore the severe local outbreaks are expected to be short-lived. No livestock deaths associated with the 2005 outbreak have been reported to ODA.
Garlic mustard
In 2006, ODA began pre-release monitoring studies in conjunction with Dr. Bernd Blossey, Cornell University, NY. Host specificity testing is currently underway and releases could be made in the next several years.
Economic benefits
Classical biological control of weeds has a good safety record, but a somewhat scanty track record of documented economic benefits. Most of the funding for biocontrol projects is utilized during the foreign exploration, host specificity testing, and introduction phases, with little appropriated for long term efficacy studies. Reported benefits cost ratios from around the world vary from 112:1 to 2:1. Biocontrol of tansy ragwort in Oregon yielded an 85 percent internal rate of return and a 15:1 benefit-cost ratio. On successful long-term projects, benefits can occur as steady stream returns, i.e., $5 million per year for the ragwort project in Oregon, where annual agency expenditures on this weed is now less than $20,000 per year.
Where feasible, it is economically advantageous to implement biocontrol in order to reduce annual losses. By actively redistributing ragwort biocontrol agents, ODA accomplished a successful regional project 5-10 years sooner than by the natural spread of the insects, averting $25-$50 million in losses to agriculture.
A partially successful biocontrol project, i.e., one that reduces weed infestations by variable percentages over large areas, can provide a positive benefit-cost ratio, even though the degree of weed control may be less than desired. If biocontrol in Oregon reduced the top 12 weeds by 30 percent, annual losses could decrease by $20 million. A 10 percent reduction of Scotch broom alone by biocontrol agents would yield $1.5 million in annual benefits.
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