Class B-Designate Control Noxious Weeds:

Control is defined as the prevention of all seed production within a single program year. With the eventual aim being a reduction of the total acreage of the plant to a point where eradication is deemed possible. In addition to the species listed below are present in the County. The board shall adopt by reference other species listed by the Washington State Noxious Weed Control Board as B-Designate species in Okanogan County. 

Listed in Okanogan County are:

LEAFY SPURGE: (Euphorbia esula L.) non-native PICTURE

Biology of Plant: is a perennial plant standing 1 to 3 feet tall. The stems are erect and usually single, some branch towards the top. Leaves are alternate, narrow, and crowded. They are yellow-green in color. Breaking a stem, leaf or root readily sees a distinctive milky sap. The flowers are a greenish-yellow in color without petals. More noticeable than the flowers are the broad, heart shaped bracts that occur opposite each other near the bases of the flowers. The bracts turn yellow as the plants approach maturity and are often mistaken for the flowers. An extensive root system containing large nutrient reserves makes leafy spurge extremely difficult to control. It reproduces by both root rhizomes and seeds.

Environment: likes ravines, pastures and roadsides. It is a problem in land that has limited cultivation, and likes semiarid to shallow aquatic environments. Most spurges contain a chemical that is toxic to humans and cattle. It also has a root sap that gives off a substance that inhibits the growth of desirable plants in the surrounding soil.

Rate of Spread: As the chambers of the seed capsule ripen, unequal pressures cause the capsule to explode, throwing the seeds as far as 20 feet. The plant’s numerous vegetative buds and its ability to spread rapidly. Spread is accelerated when tillage equipment, vehicles, and animals move seeds and root sections.

Rec./Control Methods:

    1. Manual control is not a practical method of control due to the reproduction to this plant.
    2. Chemical control has proven most effective during the Fall season if applied correctly. Application of hormone herbicides in the fall proves to be the most effective.
    3. Cultural control requires cutting off all top growth every 14 days throughout three to four growing seasons. To completely eradicate old plants with cultivation will take 3 to 4 years. Careful grazing and heavy stocking rates, of sheep and goats can help contain this plant. Neither sheep nor goats have significantly suppressed leafy spurge without carefully managed grazing.
    4. Biological Control methods have not yet been developed to the point of practical or acceptable suppression of leafy spurge. Grazing Sheep is accepted as bio-control.

      Herbicide Control: This per acre cost depends entirely on many variables, example: backpack, ATV, truck boom, or helicopter applications. Each method has a different cost rate per acre, also depending on the type of Herbicide selected, the size of the infestation and the price paid per gallon of selected Herbicide. We can give close estimates based upon the 2002 bid price cost for ground application. An applicator can cover many acres over one hour of time, so his fee charge will vary according to the difficulty of the terrain and time involved. Escort and Plateau are the recommended Herbicides to be the most effective and the cost per acre will change according to the cost of this herbicides, if it is used instead of Tordon. Also we recommend a Silicone surfactant to be used with both.

      Affects on Water Quality: Leafy Spurge increases adverse affects on fish and wildlife by water runoff and soil erosion on stream banks and sediment in lakes and rivers. Habitats and food sources are affected and greatly changed in their ecosystems. Stream flows can also altered and this affects all systems of water quality. Leafy Spurge grows along the banks of rivers and can be carried downstream to start satellite infestations.

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SCOTCH THISTLE: (Onopordum acanthium) non-native PICTURE

Biology of Plant: is a two stage biennial. The first stage of the plant is a rosette of spiny, thistle-like leaves. The second stage of the plant can grow 8-12 foot tall. The stems are upright, branched and have broad spiny wings. The leaves are large, spiny and covered with fine hair. The plant is blue-green in color with a purplish to pink flower. Flowers are numerous and are 1 to 2 inches in diameter. It reproduces primarily by seed.

Environment: best adapted for sites along rivers and streams but can be a problem in pastures, meadows, burned areas, roadways, campsites railroads, and abandoned fields.

Rate of Spread: This weed is aggressive dominating other plants with its size. Once established it’s rigid growth and spines protect the plant against grazing and trampling. The seed contains a chemical that delays germination thus allowing the seeds to germinate for up to five years. This chemical also stops the germination of other nearby plants. One scotch thistle plant can produce 20,000 seeds.

Rec./Control Methods:

    1. Manual control digging with a shovel and hand pulling is effective if completed before the plant is in full bloom. Manual control must be done a minimum of two times during the growing season.
    2. Chemical control has proven very effective if done correctly. Spraying should be done early while the plant is still young, for the most cost effective use of herbicides.
    3. Cultural control should be used in conjunction with another method of control. Reseeding and planting competitive plants, good land management, and grazing young plants with sheep can help control scotch.
    4. Biological control practices have not been successfully developed to control this pest, but the weed office has released bio-agents the same as Musk thistle.

Herbicide Control, Estimated Cost per Acre: This per acre cost depends entirely on many variables, example: backpack, ATV, truck boom, or helicopter applications. Each method has a different cost rate per acre, also depending on the type of Herbicide selected, the size of the infestation and the price paid per gallon of selected Herbicide. We can give close estimates based upon the 2002 bid price cost for ground application.

Affects on Water Quality: Scotch thistle increases adverse affects on fish and wildlife by water runoff and soil erosion on stream banks and sediment in lakes and rivers. Habitats and food sources are affected and greatly changed in their ecosystems. Stream flows can also altered and this affects all systems of water quality.

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MUSK THISTLE: (Carduus nutans L.) non-native PICTURE

Biology of Plant: Biennial and winter annual, tap root, spreads by seed, 1,000 seeds per head, 50 to 100 heads per plant, 7-8 feet tall, 90% germinate the first two years, viable 10-15 years.

Environment; prefers open direct sunlight, but will also grow in forested, shaded and moist covered areas, Musk adapts to a variety of environmental areas. Musk seems to grow in draws, steep hillsides, rocky bluffs and open slopes.

Rate of Spread; This weed is aggressive and moves rapidly moves into rangeland, waste areas, pastures and roadsides. No other documentation is found on the rate of spread for this plant.

Rec./Control Methods;

Manual control, using a shovel, is effective. We have controlled many thousands of acres with our County Hand-pull crews and it has worked very effectively.

Chemical control has proven to be extremely effective in controlling and preventing the spread for a longer period of time. The population of this noxious weed can be rapidly reduced. Spring and Fall are the ideal times to apply Herbicides, site selected herbicides can increase the growth of native vegetation and grasses to out compete the Musk thistle.

Cultural method can control Musk thistle. It does not become a problem in spring planted crops because cultivation kills the young seedlings. Mow hay fields before the seed forms to reduce the thistle population. Vigorous stands of grass also offer competition.

Biological Control, Rhinocyllus Conicus (seed head weevil), & Cheilosia corydon (crown weevil)

Herbicide Control, Estimated Cost per Acre: This per acre cost depends entirely on many variables, example: backpack, ATV, truck boom, or helicopter applications. Each method has a different cost rate per acre, also depending on the type of Herbicide selected, the size of the infestation and the price paid per gallon of selected Herbicide. We can give close estimates based upon the 2002 bid price cost for ground application;

Handpull Crew, Estimated Cost per Hour: A crew of 6 people @ 8.25 per hour = $49.50. This also depends on the amount of infestation per acre. Most of our crew covers more than 10-20 acres per hour.

Affects on Water Quality; Musk thistle usually does not grow along stream banks to cause erosion effects, but it will grow in some wetlands and crowds out native vegetation and wildlife habitat.

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DALMATIAN TOADFLAX: (Linaria dalmatica Mill.) non-native PICTURE

Biology of Plant: Toadflax is a perennial that grows 1 to 3 feet tall. The leaves are waxy, blue-green in color, dense, and alternating. The flowers are two liped, bright yellow petals with an orange bearded throat. The flowers are very similar to a snapdragon. It has an extensive and deep root system. It reproduces by seed and by root.

Soil Types: Toadflax is found in various soil types but does especially well in sandy soils.

Environment: Toadflax has been found in abandoned gardens, along roadsides, and on rangeland.

Rate of Spread: seed-eating birds and human activities spread the seeds, so this plant can spread very rapidly.

Rec./Control Methods:

    1. Manual control by hand-pulling is only effective if performed repeatedly during a season and over several years.
    2. Chemical control can be effective if applied correctly in the Fall. It should be treated in the Fall to reach the maximum control, during the dormancy stage. Due to the waxy leave adding a silicone surfactant can help improve control.
    3. Cultural control can control effectively if it is done in the spring and repeated so the plant does not have time to grow.
    4. Biological control a leaf and flower eating moth called Calophsia lunela has been released and is being monitored by Kittitas County Noxious Weed Board.

Herbicide Control, Estimated Cost per Acre: This per acre cost depends entirely on many variables, example: backpack, ATV, truck boom, or helicopter applications. Each method has a different cost rate per acre, also depending on the type of Herbicide selected, the size of the infestation and the price paid per gallon of selected Herbicide. We can give close estimates based upon the 2002 bid price cost for ground acre.

Affects on Water Quality: Same as all other Noxious weeds invading sites and affecting the habitat and wildlife areas

 

HOARY ALYSSUM:  (Berteroa incana)  non-native

Biology of Plant: Member of the Mustard family and is considered an annual or short lived perennial. The small white flowers have four petals, but it often appears to have eight because of the deep split down the middle. The leaves are grayish green and covered with hair, are also covered with rough hairs. The seeds, which are also covered with hair, are its only source of reproduction. 

Environment: Most common on gravelly soils, establishes in dry, disturbed habitats, such as roadsides and railway embankments. It is also found on meadows pastures and hayfields.

Rate of Spread:  Spreads rapidly due to the high number of seeds per plant. The plant emerges early in spring and continues to flower and produce seed until frost.

Rec./Control Methods:

  1. Manual control by hand pulling or digging can be very effective for small infestations but should be done before flowering.
  2. Chemical control several effective at label rates but may require more than one application.
  3. Cultural control good vegetative cover helps but does not prevent establishment or spread.
  4. Biological control no known biological control.

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