A New WeedWise Publication The WeedWise Program is pleased to announce a new publication entitled, Woody Weeds of Clackamas County. This resource guide is intended for use by local landowners and land managers to help them identify and manage woody weeds and naturalizing plants on their property. The Woody Weeds of Clackamas County covers a […]
It isn’t everyday that a weed manager feels the need to trade in their work boots for a day spent surrounded by home decor and scented candles. Remarkably, such was the case this week for WeedWise program manager Sam Leininger. Early in the week Sam was alerted to the possibility that a national retailer, Pier […]
Since 2016, the WeedWise program has been working to control the largest known infestation of goatsrue (Galega officinalis) in Oregon. Goatsrue is an Oregon class A noxious weed and has been deemed a high priority for control and eradication because it is toxic to livestock and spreads easily. This federal and state noxious weed is only known at a handful of other sites across Oregon and the Pacific Northwest.
Goatsrue flowers
About Goatsrue
Goatsrue is a deep-rooted perennial, with hollow stems and compound alternate leaves. The compound leaves have a terminal leaflet and 6-10 pairs of leaflets. The tip of each leaflet rapidly narrows to a fine tip. Goatsrue has pea-like flowers that vary in color from purple to white. Flowers bloom from June to October and are clustered at the end of its branches or at the leaf axils. Unlike some other members of the pea family, goatsrue lacks tendrils and grows in a more upright and bushy form rather than as a vine. The seeds are contained in pods with up to 9 mustard-colored, oblong seeds. Each plant can produce 15,000 pods a year. Additionally, these seeds may remain viable for 5-10 years in the soil.
Goatsrue closely resembles some regionally rare native plants, so we encourage landowners to contact us if they think they may have goatsrue on their property.
Robust goatsrue growth
What we Found
In May of 2016, during one of our planned weed surveys, one of our contracted survey crews discovered a large population of goatsrue on two adjacent riparian properties along the Clackamas River. This infestation affects 14 acres and is the largest known infestation of goatsrue in Oregon. We quickly began a management effort to contain and control this priority weed with the goal of eradicating the goatsrue as well as several other priority invasive plants present at these sites.
This discovery was part of an extensive survey plan for streamside properties along the Clackamas River, initiated in 2015 and continuing into the present. Twenty-five priority invasive plant species are on our target list for these surveys. Some of these species have been documented in our region and some have not. These surveys are helping us to address new priority invasive plants and better manage priority invasive plants already established here. We thank private landowners for allowing us to access their properties for these surveys!
Goatsrue herbicide application
What we are doing
The WeedWise Program initiated control soon after detecting this large goatsrue infestation. Our approach began by confirming the identity of the plant. We then followed up with a thorough review of the biology of goatsrue. Most notably, we learned that goatsrue can have a long seed dormancy period allowing seeds to grow after 10 years in the soil. As a perennial weed with a deep taproot, it is also difficult to remove by hand. Therefore, our management goals were to prevent all seed production and to target the large root systems of existing plants.
Next, we researched management strategies appropriate for this plant and this site. We consulted with the Oregon Department of Agriculture Noxious Weed Control Program and the City of Portland Bureau of Environmental Services who both have prior experience managing goatsrue. Based on this research, we selected two herbicides to treat the infestation: one to target upland populations and a second aquatically-approved herbicide to treat infestations that occur near water. The herbicide applications were planned by the WeedWise program and implemented using licensed restoration contractors.
What’s Next?
To date, our management efforts have been highly successful, but with the size and complexity of the site, we noted new seedlings emerging, as well as some patches with regrowth after herbicide application. On follow-up monitoring visits, we also found several overlooked patches that had grown in an among other vegetation. In response, we have continued to scout for missed populations and have also removed interspersed invasive Himalayan blackberry (Rubus bifrons) stands which may hide goatsrue plants. We are carrying out multiple rounds of control each year to ensure that we are not letting any plants go to seed and to continue to address regrowth.
After two years of intensive control, we have dramatically reduced the populations and are on track to eradicate this population. Eradication will require ongoing monitoring and control to address the long seed dormancy. Although we won’t be walking away from the site anytime soon, we are optimistic, knowing that the population is significantly reduced, and that we are committed to eradicating goatsrue from Clackamas County!
Project Photo Gallery
Goatsrue has pinnately compound leaves and an upright growth habit
Goatsrure growing in drainage ditch
Goatsrue growing along the edge of a small pond.
Goatsrue growth habit
Goatsrue growing in an opening within the floodplain of the Clackamas River.
Professional weed control contractors were mobilized to control this large goatsrue infestation
Goatsrue herbicide application
Goatsrue herbicide application
Goatsrue removed along pond
Successfull goatsrue control
Goatsrue regrowth after herbicide application
Goatsrue growing along the bank of a beaver pond
Goatsrue flowers
WeedWise Specialist, Jeff Lesh pulling goatsrue (Galega officianalis) near the Clackamas River
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Garden loosestrife (Lysimachia vulgaris) is one of the most recent additions to Oregon’s noxious weed list. As a class A noxious weed, the goal of land managers is to rapidly control infestations before they have a chance to gains a foothold. One critical component of this is approach is to increase awareness of this new […]
The old adage “many hands make light work” could not be truer when it comes to weed management. The WeedWise Program routinely works with a number of partnering entities and organizations across our region to combat invasive weeds. This include local, state, and federal agencies as well local non-profits and watershed councils. Our partnerships also […]
This past season we have seen a rise in the number of Oblong spurge (Euphorbia oblongata) sites appearing in Clackamas County. Oblong spurge is a class A noxious weed in the state of Oregon, and eradication of this species is required across the state. It is known to be highly aggressive and can displace native […]
There are a whole host of terms to describe weeds. The term “weeds” itself can refer to any plant that occurs in an undesirable location. Terms like “non-native“, “exotic“, “alien” or “non-indigenous” refer to plants that occur in areas where they historically did not occur. These terms make no distinction whether plants are desirable or undesirable. The term “invasive” refers to a plant or animal that exhibits aggressive growth and displace other species. Other terms like “noxious” or “nuisance” refer to plants that have special designation by the state or by a municipality the prohibits their sale or cultivation. With this broad diversity of terms, it is no wonder that many people find themselves confused and wondering how to make sense of it all.
At the WeedWise program, we hope to clarify this issue by focusing on plants we refer to as “invasive weeds”. Invasive weedsare plants that live outside their historic geographical range, and whose aggressive growth habit has a detrimental effect on our social, economic, or ecologic resources. The three key components of invasive weeds are:
They did not historically occur in our area but have been brought in either intentionally or unintentionally through human action.
They exhibit aggressive growth that displaces native or desirable vegetation and will continue to spread unless actively controlled.
They have a negative impact on our community.
These three characteristics clarify invasive weeds as those plants that pose the greatest threat to our community. By focusing on invasive weeds the WeedWise program is working to maximize its limited resources to realize the greatest benefit to Clackamas County.
Defining our priorities
All invasive weeds pose a major threat to the residents of Clackamas County, but some of these pests can be more damaging than others. In addition, the costs to control these invasive weeds greatly exceed the resources available for their management. As a result, the WeedWise program has prioritized its efforts to target invasive weeds that pose the greatest risk, have the greatest negative impact, and may still be limited enough in their distribution to allow for eradication or containment in Clackamas County. For these “priority” invasive weeds, the WeedWise program may have resources available to assistance Clackamas County landowners to control or manage these weeds. For more common invasive weeds, the WeedWise program offers technical information and consultations to improve your efforts and to make your management practices more effective.
WeedWise Classifications
Priority: These weeds are the highest priority and are actively being targeted for eradication by the WeedWise Program. Landowners are encouraged to notify the WeedWise program for assistance with these weeds and to actively control them on their property.
Containment: These weeds are a priority for management. In some areas, these weeds are so widespread that treatments are not feasible in all locations. For these weeds, infestations will be targeted for eradication when they occur outside of established containment areas. For infestations within containment areas, landowners are encouraged to contact the WeedWise program for technical assistance in developing plans to improve the management of these invasive weeds.
Maintenance: These weeds are damaging and widespread. The WeedWise Program encourages control by landowners and can assist with the development of a plan to control these weeds.
No designation: Some weeds listed below have no designation. This is because the listed weed is either not a state-listed noxious weed or because it is not known to occur in or near Clackamas County.