Crooked River Weed Management Area

Central Oregon

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C-Listed Species ... Crooked River Weed Management Area

 Common Mullein
Verbascum thapsus

Common mullein, also known as wooly mullein, is an erect herb. First year mullein plants are low growing rosettes of bluish gray-green, felt like leaves that range from 4-12 inches in length and 1-5 inches in width. Mature flowering plants are produced the second year, and grow to 5 to 10 feet in height, including the conspicuous flowering stalk. The five-petaled yellow flowers are arranged in a leafy spike and bloom a few at a time from June-August. Leaves alternate along the flowering stalks and are much larger toward the base of the plant. The tiny seeds are pitted and rough with wavy ridges and deep grooves and can germinate after lying dormant in the soil several decades.
What to look for:
Look for fuzzy gray-green rosettes and yellow flower stalks
When & where to find mullein:
Look for mullein on roadsides, waste areas, open forests land and disturbed sites.
Mullein can be manually pulled in loose soils or dug up. Keep in mind to pull before the seeds have set to reduce seed production. Chemical control can be effective as well. Roundup or milestone can be used in the rosette stage.
 Russian Thistle
Salsola kali . L
OTHER COMMON NAMES: prickly Russian thistle, saltwort, tumbleweed, windwitch, prickly glasswort
Russian thistle is an annual tap-rooted forb that grows one to three-feet tall. Seedlings look very similar to pine tree seedlings. The plant stands erect and is spiny and profusely branched. The stems of young plants have red or purple stripes. The green leaves are alternate, thread-like, stalkless, cylindrical or awl-shaped with pointed tips. Flowers are small and greenish, and lack petals. Papery, spine-tipped bracts are at the base of each flower. It typically blooms from July through October.
- Many-branched spiny shrubs that look like a “tumbleweed”
- Stems with red stripes
- Plants bristly (from spiny bracts) at maturity
- Leaves spine-tipped
Russian thistle germinates in spring (March - April), blooms from July through October, and breaks off to form “tumbleweeds” at maturity. It can flower and produce seed until the temperature drops below -3.9° C (25° F).
It commonly grows in cultivated fields, pastures, waste areas, irrigated areas, river bottoms, rangeland, disturbed areas, forest edges, and along roadsides, trails, streams and lakes. It also favors inland and coastal dunes and sandy beaches.
Russian thistle can be hand pulled so long as you are sure of its identification. Take care not to spread seeds.
Bur buttercup
Ranunculus testiculatus

Bur buttercup is an aggressive weed that can be seen after the snows have left and temperatures begin to rise. For our area this is typically March. It is an annual reproducing by seed and often within 3 weeks of leaf emergence. These plants are 2-5” tall have small 5 pedaled yellow flowers, which will turn into stiff brown burs at maturity. Leaves are alternate about 1-4” and divided into fingered segments resembling
 a bird’s foot. Bur buttercup is originally from Western
Europe and is highly toxic to livestock, especially sheep
unless dried. 

Bur buttercup can be dug out by hand if you’ve the mind to, but herbicides exist that can do a very good job. If you are spraying an area such as a driveway products containing glyphosate, like roundup, can be used to keep all vegetation out. If you are spraying areas such as pastures or lawns, then Cimmaron products are preferred. As always read and follow label rates. Your local Ag Chemical dealership carries these products and can give you more information on use. However, you decide to control the key is to get it early before it goes to seed. 
Yellow Sweet Clover
Melilotus officinalis
Yellow sweet clover is an annual or short lived perennial reaching 2 to 7 feet tall. Larger plants branch frequently and are somewhat bushy in appearance, while shorter plants are less branched and rather lanky. The stems are usually more or less erect, although sometimes they sprawl across the ground. They are glabrous, furrowed, and angular; occasionally the lower stems are ribbed light red. The leaves are alternate and divided into three finely toothed leaflets; the middle leaflet grows on a short stalk. Flowers are crowded densely at the top four inches along a central stem; each flower is attached by a minute stalk. Sweet clover blooms from June through August on second year plants.
What to look for:

Long racemes full of small yellow pea-like flowers
When & where to find yellow sweet clover:
Late spring to early fall when in bloom along roadsides, vacant lots or fallow fields
Methods of control include prescribed burning, a hot early complete first year burn followed by a hot late spring second year burn, (repeat after two years). Hand pulling is effective on small infestations when the soil is moist. Cutting can be successful if done before flowers emerge. Herbicide use is most effective when using 2,4-D or mecamine on emerging seedlings, especially following a fall burn, or after a spring burn before native vegetation emerges.
Field bindweed
Convolvulus arvensis
Field bindweed is a deep rooted perennial vine. It produces stems 2 to 4 feet in length. The leaves are alternate and 1 to 2 inches long and most often arrow-shaped, but can vary slightly. Long slender petioles connect the leave to the stem. A slender flowering stalk may develop from this petiole. This stalk occasionally branches and will produce 1 to 3 flowers. The flowers are funnelform and up to 1 inch across and white with the occasional light pink pattern. Up to 1 inch below the flower head is a pair of small green bracts.
What to look for:

Funnel form white to pink streaked flowers.
When & where to find Field bindweed:
Blooming can be seen from late spring to early fall (even though the flowers only persist for a single day) in areas like roadsides, stream banks, and cropland.
Field bindweed is difficult to eradicate because the seeds remain viable in the soil for up to 20 years and one plant can produce up to 500 seeds. The deep, extensive root system stores carbohydrates and proteins and allows it to sprout repeatedly from fragments and rhizomes following removal of aboveground growth. Herbicides such as 2,4-D or glyphosate (Roundup) can be effective. Research suggests that shading will help control this species; mulching using, paper, straw, wood chips, or black plastic can be effective in certain areas

Cichorium intybus

Perennial herb, reproducing by seeds and from roots.  The taproot is fleshy, deep, branched, with a milky sap.  The stems are hollow often rough-hairy, becoming woody and reddish with rigid branches.  The leaves are alternate, mainly clustered near the base, also long-petioled, irregularly toothed to deeply lobed, glabrous or rough-hairy.  The upper leaves are entire and dentate, oblong lanceolate and clasping the stem.  Flower-heads are numberous, 2-5-3 cm in diameter, 1-5 in clusters along branches or at tip of short stiff branches that often have gland tipped hairs. Flowers are strap-shaped ray flowers, sky-blue, sometimes white or rarely pink; bracts surrounding flower-heads in 2 rows, outer 5 about half as long as 8-10 inner, thickened and yellowish at the base, sometimes with gland-tipped hairs.  The fruits are inutely spiny; achene (seed or fruit) 2-3 mm long, obovate, light brown and darker mottled, finely granular, obscurely 4- to 5-angled, the tip blunt, beakless; pappus a minute fringed crown of tiny bristle-like scales. Fl. June to October, or in early March in southern United States and in the Pacific Northwest (Reed, 1976).
What to look for:
Sky blue to purpilish ray flowers.
When & where to find Chicory:
Blooming can be seen from summer to early fall (even though the flowers only persist for a single day) in areas like roadsides, stream banks, and cropland.


Ventenata dubia



Ventenata is a winter annual grass that germinates in the late fall and produces a seed head the following spring, about one month after annual weedy brome species (cheatgrass). Ventenata grows to be 6–18” tall

and has several distinguishing characteristics: Roots are shallow; Stems are wiry with few leaves; Awns are bent when dry.




Ventenata can outcompete perennial bunchgrasses, but the mechanism for this ability is not clear. It is high in silica, making it poorly palatable to grazing livestock. Plants dry early in the season, similar to cheatgrass and medusahead rye creating similar fire risks.




Because of the high silica content of Ventenata a dense thatch will begin to form if left untreated. Therefore, in many cases fire is used in the fall to burn of the thatch and then a residual chemical is applied. Treatment in the spring can also be effective. Multiple years of treatment is needed to deplete the seed bank in the soil.

Copyright 2019 by CRWMA