Our first 2017 weed of the month is ivy! You’ve probably seen it carpeting the ground in a natural area, or perhaps completely covering a wall, or possibly climbing high up a tree. Like many invasive plants, it was introduced as an attractive ornamental plant for landscaping. However, it escaped! Ivy has become highly invasive […]
Deck the Halls with Boughs of Holly! December is the month when our busy lives get busier. The December mad dash of shopping, baking, wrapping, and mailing, ultimately gives way to the holidays spent surrounded by our loved ones. December should be a time of enjoying each others company, not concerning ourselves with weeds. After […]
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” refers 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 weeds are 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 that they:
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.
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 exceeds 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.
Priority: These weeds are the highest priority that 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.
Maintenance: These weeds are damaging and widespread. The WeedWise Program encourages control by landowners and can assist with development of a plan to control these weeds.
Class A – a weed of known economic importance which occurs in the state in small enough infestations to make eradication or containment possible; or is not known to occur, but its presence in neighboring states make future occurrence in Oregon seem imminent. Recommended action: Infestations are subject to eradication or intensive control when and where found.
Class B – a weed of economic importance which is regionally abundant, but which may have limited distribution in some counties. Recommended action: Limited to intensive control at the state, county or regional level as determined on a site specific, case-by-case basis. Where implementation of a fully integrated statewide management plan is not feasible, biological control (when available) shall be the primary control method.
Class T – a priority noxious weed designated by the Oregon State Weed Board as a target for which the ODA will develop and implement a statewide management plan. “T” designated noxious weeds are species selected from either the “A” or “B” list[/quote]
Class A noxious weeds are usually newcomers. They are often found in only a few places in the state, and state and local weed boards hope to completely eradicate them before they get a foothold in Washington. Class A weeds are the ones you are least likely to see – but the ones that are most important to report. (If you see a plant you think might be a Class A noxious weed, please report it to your County Weed Board.)
Class B noxious weeds are abundant in some areas of the state, but absent or rare in others. The goal for Class B weeds is to control and reduce their occurrence where they are abundant, and to prevent them from spreading to those parts of the state where they are rare or absent.
Class C Noxious weeds are already widespread in Washington. In some cases, counties may require property owners to control Class C weeds, but more often counties simply try to educate residents about why controlling them is a good idea.
A = red alert, most invasive, still controllable on a regional or local scale or limited spread
B = most invasive, locally abundant
C = most invasive, widespread
D = less aggressive, wildland invaders, less impact on natural systems
E = aggressive primarily in horticultural/agricultural situations; note: this category is incomplete
F= needs more info, should be noted if and where it’s a problem
W= watch list
‘A’ Listed Weeds: Early Detection. Some of these weeds are found outside the CWMA region but could invade the region at any time in the future. Some have been found in the CWMA in isolated populations. Management focuses on developing an Early Detection Rapid Response (EDRR) network of people and organizations to identify sites.
‘B’ Listed Weeds: High Importance. These weeds can be locally abundant, but may also occur in spotty distribution across the landscape. Management focuses on inventory to determine distribution, followed by eradication of small, isolated populations, and control or containment of larger infestations.
‘C’ Listed Weeds: Common. These weeds occur across the landscape at a level where eradication, containment or control is not economically feasible. Management focuses on removing them from ecologically, socially and economically important sites and slowing their spread through prevention actions. When available, biological controls should be used.
‘W’ Listed Weeds: Watch list. These weeds display invasive qualities in our area or similar ecosystems, but they have not yet proven to be problematic. Management focuses on inventory to determine if the plant is behaving aggressively followed by eradication or close observation going into the future. The purpose of the “Watch list” is to gather more information on suspect weeds, as well as monitor for occurrence or spread. Information collected may be used to justify future inclusion on the state
| Common Name | Scientific Name | Oregon Classification | Washington Classification | WeedWise Classification | 4-County CWMA | Columbia Gorge CWMA |
|---|---|---|---|---|---|---|
| Velvetleaf | Abutilon theophrasti | B | B | B | B | |
| Barbed Goatgrass | Aegilops triuncialis | A,T | not listed | priority | A | W |
| Tree of Heaven | Ailanthus altissima | B | C | maintenance | B | C |
| Garlic mustard | Alliaria petiolata | B,T | A | priority | B | A |
| Wild chervil | Anthriscus sylvestris | not listed | B | maintenance | not listed | B |
| Italian arum | Arum italicum | not listed | C | maintenance | B | B |
| False brome | Brachypodium sylvaticum | B | A | priority | B | A |
| Butterfly bush | Buddleja davidii (Buddleja varabilis) | B | B | maintenance | B | B |
| Drooping sedge | Carex pendula | W | not listed | priority | W | B |
| Meadow knapweed | Centaurea × moncktonii (C. pratensis) | B | B | maintenance | B | B |
| Spotted knapweed | Centaurea stoebe (C. maculosa) | B,T | B | maintenance | B | B |
| Canada thistle | Cirsium arvense | B | C | maintenance | C | C |
| Bull thistle | Cirsium vulgare | B | C | maintenance | D | C |
| Old man's beard | Clematis vitalba | B | C | maintenance | B | C |
| Poison hemlock | Conium maculatum | B | B | maintenance | B | B |
| English hawthorn | Crataegus monogyna | not listed | C | maintenance | C | C |
| Yellow nutsedge | Cyperus esculentus | B | B | maintenance | B | B |
| Scotch broom | Cytisus scoparius | B | B | maintenance | C | B |
| Spurge laurel | Daphne laureola | B | B | priority | B | B |
| Goatsrue | Galega officinalis | A, T | A | priority | A | A |
| Herb robert | Geranium robertianum | B | B | maintenance | C | B |
| English ivy | Hedera helix | B | C | maintenance | C | B |
| Irish ivy | Hedera hibernica | B | C | maintenance | C | B |
| Small broomrape | Orobanche minor | B | not listed | maintenance | D | A |
| African rue | Peganum harmala | A,T | not listed | priority | A | W |
| Ribbongrass | Phalaris arundinacea var. picta | B,T | C | maintenance | not listed | C |
| Reed canarygrass | Phalaris arundinacea | W | C | maintenance | not listed | C |
| Bohemian knotweed | Fallopia × bohemica ( Polygonum × bohemicum ) | not listed | B | priority | C | B |
| Japanese knotweed | Fallopia japonica ( Polygonum cuspidatum ) | B | B | priority | B | B |
| Giant knotweed | Fallopia sachalinensis ( Polygonum sachalinensis ) | B | B | priority | B | B |
| Curly-leaf pondweed | Potamogeton crispus | not listed | C | maintenance | C | C |
| Lesser celandine | Ranunculus ficaria | B | B | maintenance | B | B |
| Armenian (Himalayan) blackberry | Rubus bifrons (R. armeniacus, R. procerus, R. discolor) | B | C | maintenance | C | C |
| Evergreen blackberry | Rubus laciniatus | not listed | C | maintenance | C | C |
| Tansy ragwort | Senecio jacobaea | B | B | maintenance | B | B |
| Common groundsel | Senecio vulgaris | not listed | C | maintenance | not listed | C |
| Blessed milk thistle | Silybum marianum | B | A | priority | A | A |
| Perennial sowthistle | Sonchus arvensis ssp. arvensis | not listed | C | maintenance | D | C |
| Common tansy | Tanacetum vulgare | not listed | C | maintenance | C | C |
| Garden yellow loosestrife | Lysimachia vulgaris | A,T | B | priority | A | W |
| Spiny cocklebur | Xanthium spinosum | B | C | priority | D | C |
| Syrian bean-caper | Zygophyllum fabago | A | A | priority | A | A |
| Biddy-biddy | Acaena novae-zelandiae | B | not listed | not listed | W | |
| Russian Knapweed | Acroptilon repens | B | B | priority | A | B |
| Pheasant eye | Adonis aestivalis | B | not listed | priority | not listed | not listed |
| Jointed goatgrass | Aegilops cylindrica | B | C | priority | not listed | C |
| Ovate Goatgrass | Aegilops ovata | A | not listed | priority | A | W |
| Camelthorn | Alhagi pseudalhagi | A | B | priority | A | A |
| Blackgrass | Alopecurus myosuroides | not listed | C | A | W | |
| Yellow tuft | Alyssum corsicum | A,T | not listed | priority | A | W |
| Yellow tuft | Alyssum murale | A,T | not listed | priority | A | W |
| Ragweed | Ambrosia artemisiifolia | B | not listed | priority | D | B |
| Skeletonleaf bursage | Ambrosia tomentosa | A | not listed | priority | A | not listed |
| False indigo bush | Amorpha fruticosa | B | B | not listed | B | |
| Annual bugloss | Anchusa arvensis | not listed | B | not listed | B | |
| Common bugloss | Anchusa officinalis | B,T | B | priority | A | B |
| Absinth wormwood | Artemisia absinthium | not listed | C | not listed | C | |
| South African capeweed | Artotheca calendula | W | not listed | not listed | W | |
| Giant reed | Arundo donax | W | not listed | priority | not listed | A |
| Common barberry | Berberis vulgaris | not listed | C | not listed | W | |
| Hoary allysum | Bertoa incana | A,T | B | priority | A | B |
| White bryonia | Bryonia alba | A | B | priority | A | A |
| Flowering rush | Butomus umbellatus | A,T | A | priority | W | A |
| Fanwort | Cabomba caroliniana | not listed | B | not listed | W | |
| Plumeless thistle | Carduus acanthoides | A,T | B | priority | A | A |
| Welted thistle | Welted thistle | A,T | not listed | priority | not listed | not listed |
| Musk thistle | Carduus nutans | B | B | priority | E | B |
| Italian thistle | Carduus pycnocephalus | B | A | priority | D | A |
| Slender-flowered thistle | Carduus tenuiflorus | B | A | priority | D | A |
| Smooth distaff thistle | Carthamus baeticus | A | not listed | priority | A | W |
| Woolly distaff thistle | Carthamus lanatus | A,T | not listed | priority | A | W |
| Whitestem distaff thistle | Carthamus leucocaulos | W | not listed | not listed | W | |
| Wild safflower | Carthamus oxyacantha | W | not listed | not listed | W | |
| Longspine sandbur | Cenchrus longispinus | not listed | C | not listed | C | |
| Purple starthistle | Centaurea calcitrapa | A,T | A | priority | A | A |
| Diffuse knapweed | Centaurea diffusa | B | B | B | B | |
| Iberian starthistle | Centaurea iberica | A,T | not listed | priority | A | A |
| Brown knapweed | Centaurea jacea | not listed | B | F | B | |
| Big-headed knapweed | Centaurea macrocephala | W | A | not listed | A | |
| Black knapweed | Centaurea nigra | not listed | B | not listed | B | |
| Vochin knapweed | Centaurea nigrescens | not listed | A | not listed | A | |
| Yellow starthistle | Centaurea solstitialis | B | B | priority | A | B |
| Feather-headed knapweed | Centaurea trichocephala | W | not listed | not listed | W | |
| Squarrose knapweed | Centaurea virgata | A,T | not listed | priority | not listed | A |
| Rush skeletonweed | Chondrilla juncea | B, T | not listed | priority | D | B |
| Oriental clematis | Clematis orientalis | not listed | A | not listed | A | |
| Field bindweed | Convolvulus arvensis | B,T | C | C | C | |
| Jubata grass | Cortaderia jubata | B | C | priority | W | B |
| Pampass grass | Cortaderia selloana | not listed | C | not listed | C | |
| Common crupina | Crupina vulgaris | B | A | not listed | W | |
| Smoothseed alfalfa dodder | Cuscuta approximata | not listed | C | not listed | C | |
| Japanese dodder | Cuscuta japonica | A | not listed | priority | A | W |
| Dodder | Cuscuta spp. | B | not listed | not listed | B | |
| Houndstongue | Cynoglossum officinale | B | B | priority | D | B |
| Purple nutsedge | Cyperus rotundus | A | not listed | priority | A | A |
| Portuguese broom | Cytisus striatus | B,T | not listed | W | W | |
| Wild carrot | Daucus carota | not listed | C | maintenance | C | C |
| Cape ivy | Delairea odorata | A | not listed | priority | A | W |
| Common teasel | Dipsacus fullonum | not listed | C | maintenance | C | C |
| Cutleaf teasel | Dipsacus laciniatus | B | not listed | priority | not listed | W |
| Tree echium | Echium pininana | W | not listed | not listed | W | |
| Paterson's curse | Echium plantagineum | A,T | not listed | priority | A | W |
| Viper bugloss | Echium vulgare | W | B | not listed | B | |
| South American waterweed | Egeria densa | B | B | maintenance | C | B |
| Water hyacinth | Eichhornia crassipes | W | not listed | not listed | not listed | |
| Russian olive | Elaeagnus angustifolia | not listed | C | not listed | C | |
| Hairy willow-herb | Epilobium hirsutum | not listed | B | not listed | B | |
| Spanish heath | Erica lusitanica | B | not listed | W | W | |
| Toothed spurge | Euphorbia dentata | W | not listed | not listed | W | |
| Leafy spurge | Euphorbia esula | B, T | B | priority | B | A |
| Myrtle spurge | Euphorbia myrsinites | B | B | maintenance | E | B |
| Oblong spurge | Euphorbia oblongata | A,T | A | priority | A | A |
| Common fennel | Foeniculum vulgare | not listed | B | C | B | |
| French broom | Genista monspessulana | B | A | W | A | |
| Shiny leaf geranium | Geranium lucidum | B | A | maintenance | B | A |
| Reed sweetgrass | Glyceria maxima | not listed | A | not listed | A | |
| Babysbreath | Gypsophila paniculata | not listed | C | not listed | C | |
| Halogeton | Halogeton glomeratus | B | not listed | priority | not listed | W |
| Texas blueweed | Helianthus ciliaris | not listed | A | not listed | A | |
| Spikeweed | Hemizonia pungens | B | C | priority | not listed | C |
| Giant hogweed | Heracleum mantegazzianum | A, T | A | priority | A | A |
| Yellow hawkweed | Hieracium × floribundum | A,T | B | priority | A | A |
| Polar hawkweed | Hieracium atratum | not listed | B | not listed | W | |
| Orange hawkweed | Hieracium aurantiacum | A,T | B | priority | A | A |
| Meadow hawkweed | Hieracium caespitosum | B,T | B | priority | A | B |
| Whiplash hawkweed | Hieracium flagellare | not listed | B | not listed | W | |
| Queen-devil hawkweed | Hieracium glomeratum | not listed | B | not listed | W | |
| Common hawkweed | Hieracium lachenalii | not listed | B | not listed | B | |
| Pale hawkweed | Hieracium lactucella | not listed | B | not listed | W | |
| Smooth hawkweed | Hieracium laevigatum | not listed | B | not listed | W | |
| Spotted hawkweed | Hieracium maculatum | not listed | B | not listed | W | |
| Wall hawkweed | Hieracium murorum | not listed | B | W | W | |
| Mouse-ear hawkweed | Hieracium pilosella | A,T | B | priority | A | A |
| King-devil hawkweed | Hieracium piloselloides | A,T | B | priority | A | A |
| European hawkweed | Hieracium sabaudum | not listed | B | not listed | W | |
| Hydrilla | Hydrilla verticillata | A | A | priority | W | A |
| Common frogbit | Hydrocharis morsus-ranae | A | not listed | priority | A | W |
| Black henbane | Hyoscyamus niger | not listed | C | not listed | C | |
| St. Johnswort | Hypericum perforatum | B | C | maintenance | C | C |
| Common catsear | Hypochaeris radicata | not listed | C | maintenance | C | C |
| Spotted jewelweed | Impatiens capensis | W | not listed | maintenance | C | W |
| Policeman's helmet | Impatiens glandulifera | B | B | priority | B | B |
| Yellow flag iris | Iris pseudacorus | B | C | B | B | |
| Dyers woad | Isatis tinctoria | B | A | not listed | A | |
| Kochia | Kochia scoparia | B | B | priority | not listed | B |
| Yellow archangel | Lamiastrum galeobdolon | B | B | maintenance | B | B |
| Perennial peavine | Lathyrus latifolius | B | not listed | maintenance | C | C |
| Lens-podded whitetop | Lepidium chalepensis | B | not listed | priority | A | B |
| Hoary cress | Lepidium draba | B | C | priority | A | B |
| Perennial pepperweed | Lepidium latifolium | B,T | B | priority | A | B |
| Hairy whitetop | Lepidium pubescens | B | C | priority | not listed | C |
| Lepyrodiclis | Lepyrodiclis holosteoides | not listed | C | not listed | W | |
| Oxeye daisy | Leucanthemum vulgare | not listed | C | maintenance | C | C |
| West Indian spongeplant | Limnobium laevigatum | A | not listed | priority | A | W |
| Dalmatian toadflax | Linaria dalmatica | B, T | B | B | B | |
| Yellow toadflax | Linaria vulgaris | B | C | maintenance | B | C |
| Water primrose | Ludwigia grandiflora | B, T | not listed | maintenance | not listed | B |
| Water primrose | Ludwigia hexapetala | B | B | maintenance | not listed | B |
| Water primrose | Ludwigia peploides ssp. montevidensis | B | A | maintenance | A | A |
| Rose campion | Lychnus coronaria | W | not listed | not listed | W | |
| Purple loosestrife | Lythrum salicaria | B | B | priority | B | B |
| Wand loosestrife | Lythrum virgatum | not listed | B | not listed | W | |
| Scentless mayweed | Matricaria perforata | not listed | C | not listed | C | |
| Wild four o'clock | Mirabilis nyctaginea | not listed | A | not listed | W | |
| Variable-leaf milfoil | Myriophyllum heterophyllum | not listed | A | not listed | A | |
| Eurasian watermilfoil | Myriophyllum spicatum | B | B | priority | C | B |
| Parrots feather | Myrophyllum aquaticum | B | B | maintenance | B | B |
| Matgrass | Nardus stricta | A,T | not listed | priority | A | W |
| Fragrant water lily | Nymphaea odorata | not listed | C | D | C | |
| Yellow floating heart | Nymphoides peltata | A, T | B | priority | A | A |
| Scotch thistle | Onopordum acanthium | B | B | priority | A | B |
| Taurian thistle | Onopordum tauricum | A,T | not listed | priority | A | W |
| Mile-a-minute weed | Persicaria perfoliata | W | not listed | not listed | W | |
| Japanese butterbur | Petasites japonica | not listed | not listed | W | B | |
| Common reed | Phragmites australis ssp. australis | B | B | priority | A | B |
| American pokeweed | Phytolacca americana | W | not listed | B | A | |
| Hawkweed oxtongue | Picris hieracioides | not listed | B | not listed | B | |
| Himalayan knotweed | Polygonum polystachyum | B | B | priority | not listed | B |
| Sulfur cinquefoil | Potentilla recta | B | B | priority | A | B |
| Kudzu | Pueraria lobata | A,T | A | priority | A | A |
| Austrian fieldcress | Rorippa austriaca | not listed | C | not listed | C | |
| Creeping yellow cress | Rorippa sylvestris | B | not listed | not listed | A | |
| Sweet briar rose | Rosa rubiginosa ( R.eglanteria ) | W | not listed | not listed | W | |
| Ravennagrass | Saccharum ravennae | A | A | priority | A | A |
| Grass-leaved arrowhead | Sagittaria graminea | not listed | B | not listed | W | |
| Delta arrowhead | Sagittaria platyphylla | W | not listed | A | not listed | |
| Mediterranean sage | Salvia aethiopis | B | A | not listed | A | |
| Meadow clary | Salvia pratensis | not listed | A | not listed | W | |
| Clary sage | Salvia sclarea | W | A | not listed | W | |
| Ricefield bulrush | Schoenoplectus mucronatus | W | A | D | A | |
| Cereal rye | Secale cereale | not listed | C | not listed | C | |
| White cockle | Silene latifolia ssp. alba | not listed | C | not listed | C | |
| Silverleaf nightshade | Solanum elaeagnifolium | A | A | priority | A | A |
| Buffalobur | Solanum rostratum | B | C | D | C | |
| Sticky nightshade | Solanum sisymbriifolium | W | not listed | not listed | W | |
| Field Burrweed | Soliva sessilis | not listed | C | not listed | W | |
| Johnsongrass | Sorghum halepense | B | A | priority | E | A |
| Smooth cordgrass | Spartina alterniflora | A, T | A | priority | A | W |
| Common cordgrass | Spartina anglica | A,T | A | priority | A | W |
| Dense-flowered cordgrass | Spartina densiflora | A,T | A | priority | A | W |
| Saltmeadow cordgrass | Spartina patens | A,T | A | priority | A | W |
| Spanish broom | Spartium junceum | B | A | priority | F | A |
| Swainsonpea | Sphaerophysa salsula | B | C | not listed | C | |
| Water soldiers | Stratiotes aloides | A | not listed | priority | A | not listed |
| Medusahead rye | Taeniatherum caput-medusae | B | not listed | priority | C | C |
| Saltcedar | Tamarix ramosissima | B,T | B | W | B | |
| Spurge flax | Thymelaea passerina | not listed | A | not listed | W | |
| European water chestnut | Trapa natans | A | not listed | priority | A | A |
| Puncturevine | Tribulus terrestris | B | B | priority | C | B |
| Coltsfoot | Tussilago farfara | A | not listed | priority | A | A |
| Narrowleaf cattail | Typha angustifolia | not listed | C | not listed | C | |
| Southern cattail | Typha domingensis | not listed | C | not listed | W | |
| Miniature cattail | Typha minima | not listed | C | not listed | W | |
| White cattail | Typha x glauca | not listed | C | not listed | W | |
| Gorse | Ulex europaeus | B,T | B | priority | A | A |
| North Africa grass | Ventenata dubia ( V. avenacea ) | W | not listed | not listed | C | |
| Japanese eelgrass | Zostera japonica | W | C | not listed | W |
