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Weed of the Week – Spotted Knapweed

Thursday, August 26th, 2010

Notice the dark spots on the bracts under the blossom, this is where the weed gets its name Spotted Knapweed.

Introduction Spotted knapweed is the number one problem on rangelands in western Montana. Spotted knapweed is dramatically interfering with the Montana’s unique ecosystems. It was accidentally introduced to the United States through contaminated alfalfa and contaminated soil used as ship ballast.

The first report of this weed in Ravalli County was 1921. Knapweed has infested 2-5 million acres in Montana, with potential to spread to the 34 million susceptible acres in the state. Spotted knapweed has been recorded in every county in Montana.

Concerns Knapweed has changed the face of our lands in western Montana. Ranchers, wildlife enthusiast, hunters, foresters, hikers, and fisherman are impacted by the dramatic affect that knapweed is having on our ecosystem. Spotted knapweed is particularly hard to manage due to its ability to occupy a variety of sites and habitats. This weed will aggressively out-compete native vegetation.

Watersheds throughout the state are reaping the negative effects of the soil erosion that knapweed causes. The soil erosion caused by spotted knapweed is degrading fisheries and water quality. Spotted knapweed is impacting Montana’s economy in a serious way. The negative effect knapweed has on Montana’s economy is an estimated $42 million annually.

Identification Spotted knapweed is a pinkish-purple flower and the plant grows 1-3 feet tall. The bracts underneath the flowers have dark spotted tips that are also fringed. Spotted knapweed blooms from mid to late July and through September. Each individual flower will bloom for 2-6 days. The flowers will reopen after 20 days to disperse seeds. One knapweed plant can produce up to 1000 seeds and remain viable in the soil for 8 years. You will begin to see spotted knapweed rosettes in early April. Knapweed can grow to nearly 4 feet tall on moist sites.

What can you do? For pastures and rangelands that have not been infested, prevention is key. Avoid transporting seeds from infested sites. Seeds can attach themselves to vehicles, clothes, and animals. Use only certified weed-seed free seed and hay in non-infested areas. For infested areas integrated weed management methods need to be employed. Small infestations can be controlled through timed hand pulling, which should take place when the soil is moist and prior to the plant going to seed. Pulled plants should be bagged and disposed of or burned.

Plowing an infested area is feasible, if plowed down to 7 inches below soil surface and if the area is reseeded with desirable vegetation. Plowing may cause dormant knapweed seeds in the soil to germinate. This method is best if used with herbicide treatment or grazing. Sheep, goats, and cattle will graze spotted knapweed at certain times. Grazing on knapweed should be timed for when the grasses have gone dormant. Sheep grazing in combination with herbicide use can be fairly effective. There are multiple insects that exist in Montana as a mean of controlling knapweed. The success of knapweed eradication requires a long-term commitment.

Visit the MWCA Weed ID pages for additional information and pictures of spotted knapweed.

This series of articles was developed by Ravalli County. If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Hoary alyssum–A weed to watch for on your property

Friday, August 20th, 2010

Dr. Jane Mangold, MSU Assistant Professor and Extension Invasive Plant Specialist, just published an article about a weed to keep an eye out for during the late summer. The following is an excerpt from her article:

Hoary alyssum plants that were mowed once, but re-grew and produced seed along a trail (photo courtesy of Hilary Parkinson).

Have you noticed a small, white-flowered mustard growing prolifically in your neighborhood? It could be the noxious weed hoary alyssum (Berteroa incana). Hoary alyssum was added to the state noxious weed list in 2008, and may not be as familiar as other notables like spotted knapweed, Canada thistle or leafy spurge.

However, if you live in southwestern Montana, where this weed is most prevalent, you’ve probably seen it along a bike trail or road, in a waste area or pasture, or even in your yard. It flowers from spring through late fall, and is currently very noticeable as other vegetation begins to die back for the season.

Read the complete MSU news article here.

Visit the MWCA Weed ID pages for additional information and pictures of Hoary alyssum.

Weed of the Week – Common Tansy

Thursday, August 19th, 2010

Common Tansy, photo credit: Jerry R. Oldenettel

Common Tansy is also known as golden buttons and garden tansy. Common tansy was introduced from Europe into colonial North America in the 1600’s as an ornamental plant and for medicinal uses. Ironically, common tansy contains alkaloids that are toxic to humans and livestock if consumed in large quantities. Common Tansy was first discovered in Silver Bow County in 1936. Common tansy is a big problem in most counties on the roadsides, ditches, and waste areas.

Concerns Common tansy is unpalatable to livestock and mildly poisonous. The presence of this weed reduces species diversity, wildlife habitat, and livestock forage. It has a tendency to grow near water, which allows the plant to spread easily and makes control difficult. The root system on common tansy allows the plant to spread laterally and by broken pieces of roots.

Identification Common tansy is a perennial forb that can reproduce by rootstalk or seed. One of the most notable features of tansy is the potent smell cause by crushing the leaves. The flowers on common tansy are yellow-orange button-like flower heads. Flowers of the common tansy are numerous; there can be 20-100 flowers in flat-topped, dense clusters. The leaves on the common tansy are deeply divided into leaflets with toothed margins, almost fern-like. The leaves are alternately arranged and are uniform in size. This plant will grow between 1-6 feet tall and the stem is often a purplish-red color.

What can you do? Due to the extensive root system of common tansy an integrated management approach is necessary. Preventing the spread of this weed into new areas is one of the easiest management techniques. Mowing and hand-pulling has marginal results due to the root system of tansy and they are best used in combination with other controls. Mowing and pulling will help prevent seed production. Maintaining healthy desirable vegetation will aid in controlling common tansy. Grazing in infested areas should be monitored closely to maintain desired species. There are a couple of effective chemicals for common tansy. For recommendations on those, call the weed district,

Visit the MWCA Weed ID pages for additional information and pictures of common tansy.

This series of articles was developed by Ravalli County. If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Weed of the Week – Blueweed

Thursday, August 12th, 2010

Blueweed - photo by Kellieanne Morris, Ravalli County MT Weed District

Introduction

Blueweed or viper’s bugloss is native to Europe and has invaded much of the eastern U.S. and parts of the western U.S. The first record of this plant in Montana was in 1916. It was listed as a category 2 noxious weed on our state list in March of 2008. Blueweed thrives in gravel bars along rivers and also does well in irrigated pastures.

Concerns
Blueweed can be toxic to horses, sheep, and cattle. The hairs that cover the plant may also act as a skin irritant for humans. This plant can become quite large greatly reducing the productivity of grazable lands due to it being unpalatable. It has the potential to ruin hay due to its high moisture content. It also has the ability to destroy wildlife habitat and native plant biodiversity. It reproduces by seeds that stick to clothing, animal fur, and feathers and may also be disperse by flowing water. Each plant produces between 500 and 2000 seeds.

Identification
Blueweed is most easily identified by its bell shaped flowers that come in shades of blue, pink, and purple. The flowers bloom a few at a time in a scorpoid raceme (resembles a scorpion’s tail). Four or five, usually pink stamen stick out from the center of the bell shaped flowers. Blueweed is a biennial, meaning that it lives for two years. The first year that this plant emerges it is in the form of a rosette. Second year plants typically bolt and produce flowers. The stems are a grayish-green color and are covered with hairs and black dots. The leaves are lance shaped and are also covered with hairs. The plant can be anywhere from 5 inches to 3 feet in height. From a distance it may resemble lupine.

What can you do?

This tap rooted plant can be hand pulled (with gloves and long sleeved shirts) or dug up with good results in small infestations. Mowing can help to reduce the seed production if repeated throughout the growing season but is not a long term solution. Herbicide is an effective control method when applied correctly. Call your local weed district for recommendations on herbicides. As always an integrated weed management plan utilizing all effective means of control and revegetation is the best option for reducing and eradicating blueweed. If you have any questions about blueweed or any other noxious weeds call your local weed district.

Visit the MWCA Weed ID pages for additional information and pictures of blueweed.

This series of articles was developed by Ravalli County. If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Posts related to: Blueweed, Echium vulgare, noxious weeds, Priority 2A Weed, Viper's Bugloss
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Weed of the Week – Yellowflag Iris

Thursday, August 5th, 2010

Yellowflag Iris Flower

Introduction

Yellowflag iris, native to Europe, Great Britain, North Africa, and the Mediterranean region can be found almost everywhere in the United States. It is found in wetlands, along the edge of ponds, lakes, or slow moving streams or rivers and is fast becoming one of our most aggressive wetland bullies. This plant can grow in full sun or part shade. When it blooms in late spring to early summer it is unmistakable with its large pale to bright yellow iris flowers. The flowers look very similar to a garden iris but they are often streaked with brown to purple lines. Yellowflag is often mistaken for cattails when the blooms are not present. The best way to distinguish this plant when flowers are not out is to look for the large fruit pod in the summer or the fan-shaped plant-base other times of the year.

Concerns

Yellowflag is a popular wetland ornamental that is still sold on-line. It is very easily spread downstream of its original location both by broken off pieces of rhizome (roots) and by floating seeds. This plant forms incredibly dense stands connected by rhizomes. Several hundred flowering plants can be connected in one rhizome mass. These stands become so dense that they choke out all other native and beneficial wetland vegetation. The dense rhizome masses trap sediment, which reduces water flow affecting fish, plants, and animals. Yellowflag iris is toxic to livestock and other herbivores and the resins that it contains will cause skin irritation in humans.

Identification

This perennial has showy yellow flowers that resemble a typical garden iris. Each stem may have several flowers that each have 3 large downward facing yellow sepals that are streaked with brown or purple lines and 3 upward facing yellow petals. The plant including the flower stalk is 3-4 feet tall. The leaves are mostly basal and are folded around the stem in a fan-like fashion. The leaves will stay green until harsh winter weather begins.

What can you do?

Yellowflag iris is difficult to control both by mechanical means and with herbicide. When hand pulling or digging make sure to wear gloves because of the irritating resins and also make sure to get all pieces of the rhizome mass. One small fragment can start a new mass of plants. To use herbicides on yellowflag an aquatic license is required because of its proximity to water. If you have yellowflag iris on your property or you know where this plant can be found please contact your local county weed district.

Visit the MWCA Weed ID pages for additional information and pictures of yellowflag iris.

This series of articles was developed by Ravalli County. If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Posts related to: Iris pseudacorus, noxious weeds, Priority 2A Weed, Yellowflag Iris
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Weed of the Week – Saltcedar

Thursday, July 29th, 2010

Introduction

Saltcedar is native to Eurasia but was introduced to North American in the early 1800’s as an ornamental and also for erosion control. It was quick to escape cultivation and has since been spreading rapidly. This attractive shrub has characteristics similar to an evergreen but looses its leaves in the colder months and is therefore considered deciduous. Saltcedars readily establish along waterways, streams, canals, banks, drainage areas, and anywhere that the soils are exposed to an extended period of moisture.

Saltcedar has become well established throughout the southwestern United States and Mexico. There are also extensive infestations in many of the northern states and small but well-established stands in Oregon, Idaho, Montana, Wyoming, South Dakota, and North Dakota. In most western Montana counties, these shrubs are found as ornamental in landscaped yards.

Concerns

This long-lived shrub (50-100 years) can spread by both vegetative re-growth and seeds. Each flowering shrub produces around 600,000 seeds. Not only are they long lived and have great reproductive capabilities, but they also grow extremely rapidly. Most of these shrubs can flower the same year they germinate. They exclude native vegetation by exuding salts above and below ground. This creates a saline crust, which inhibits other plants from growing in close proximity. The other main concern with Saltcedar is its consumption of large quantities of water. One shrub can consume up to 250 gallons of water in 1 day. This can result in lowering the ground water and drying up springs and marshes, which in turn lessens the amount of water available in riparian areas. Saltcedar’s dense roots also slow down river flow, which increases deposition of sediments along the river bank. This widens the riparian zones causing a severe reduction in streamflow or rechanneling, which creates more habitat for Saltcedar to colonize.

Identification

This shrub can reach heights of up to 25 feet and has dense branches that often make it many feet wide. The narrow leaves of a Saltcedar resemble those of a juniper but they fall off in the colder months unlike junipers. This shrub is also known as a smoke tree because of it beautiful plumes of deep pink to white flowers that crowd the tips of the branches. The bark of a Saltcedar is reddish-brown, while the wood is soft and white. The smooth bark becomes furrowed with age.

What can you do?

Saltcedar is very difficult to control. A combination of methods is the most effective means of control. Cutting the stump and immediately applying herbicide has proved to be successful. The herbicide has to be applied within 1 minute of cutting the shrub or it will not penetrate into the stump. If you have a Saltcedar or you know where one is please contact your local weed district. We will be happy to help in the proper control of these highly invasive shrubs.

Visit the MWCA Weed ID pages for additional information and pictures of saltcedar.

This series of articles was developed by Ravalli County. If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Weed of the Week – Houndstongue

Thursday, July 22nd, 2010

Introduction

Houndstongue was introduced into the U.S. in the 1900’s from Eurasia as a cereal contaminant. It is also known as sheep’s lice, dog’s bur, beggar’s lice, woolmat, and glovewort. The seed of houndstongue has been said to be the inspiration for Velcro.

Concerns

In Montana, houndstongue infests an estimated 36,000 acres. Where it is established it will displaces native vegetation and cause problems on pasturelands. The taproot of houndstongue grows deep into the soil and is very efficient at capturing soil nutrients and water reducing what is available for beneficial native grasses and forbs.

It has an uncanny ability to disperse its seeds. The seeds of houndstongue are covered with Velcro-like barbs that attach to clothing, hair, fur, and feathers. They can be transported long distances into new areas by animals, people, vehicles, etc. Each plant can produce up to 2000 seeds that can remain viable on the parent plant for 2-3 years.

Houndstongue is not generally palatable to grazing animals but on occasion when they are in a confined area with nothing else to eat they will graze on it. This can be a problem because houndtongue contains poisonous chemicals that in high doses can kill an animal. The chemical found in houndstongue is pyrroli-zidine alkaloids, which will cause liver damage in horses and cattle but not in sheep.

Identification

Houndstongue is a member of the Boraginaceae (Borage) family. It is a biennial, meaning that its lifecycle is completed in two years. The first year a rosette will emerge and the second year flowering stocks will grow up to 4 feet tall. The rosette and flowering stock leaves are oblong and are covered in soft white hairs. The deep vienation on the leaves is said to resemble a hound’s tongue, which lead to its common name. The flowers range from red to a deep burgundy. Each flower produces a seed cluster containing 3-4 teardrop-shaped fruits or nutlets. It begins flowering in mid-June.

What can you do?

The most important management tool for houndstoungue is prevention. It is important to not let this weed spread and establish in new areas. You can help stop the spread of this weed by: containing infestations, limiting weed seed dispersal, identifying and eradicating new infestations, minimizing soil disturbance, planting competitive grasses, and properly grazing infested areas.

Hand-pulling this weed is beneficial, as long as at least 2 inches of the root crown is removed. After removing houndstongue bag or burn the weed in order not to spread the seeds. An effective biological control has not yet been release in Montana. There are also herbicides that work well on houndstongue. For more information on houndstongue or any other weed, call your local county weed district.

Visit the MWCA Weed ID pages for additional information and pictures of Houndstongue.

This series of articles was developed by Ravalli County. If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Weed of the Week – Canada Thistle

Monday, July 19th, 2010

Introduction

Canada thistle is native to Europe and northern Asia and was brought to the United States in the early 1600’s as a contaminant in grain. By the 1950’s, Canada thistle was declared a noxious weed in 43 states. Canada thistle was partially responsible for the existence of noxious weed laws. In the 1900’s, the Canada thistle law was enacted. It gave a person the right to trespass onto someone else’s property in the name of Canada thistle eradication.

Concerns

Canada thistle is an aggressive competitor. This weed has a long creeping root system that will steal precious nutrients and water from native vegetation. The height of this weed also shades the ground below making it very difficult for grasses and forbs to grow. Canada thistle will form colonies in areas that have been recently disturbed, abandoned fields, ditches, and prairies.

The presence of this weed will change the plant structure of communities and decrease biodiversity. Canada thistle can be a huge problem on agricultural land due to the fact that it is an alternate host for some insects and pathogens that are known to attack certain crops. It is also difficult and expensive to control.

Identification

This thistle is unique because it is a perennial, whereas most thistles are biennial, this also makes it harder to control. Canada thistle can grow from 1 to 4 feet tall. The leaves of this thistle are attached alternately along the stem; they are lance-shaped, lobed and spine-tipped. The leaves get gradually smaller as they progress up the stem. The stem is branched and sometimes hairy, but it lacks spines.

The flowers of the Canada thistle are usually purple and sometimes white. They are ½ to ¾ inch in diameter and grow in clusters at the end of stems. Each plant can produce up to 5,300 seeds that are easily distributed by the wind due to the tufts of hair attached to them. The seeds remain viable in the soil for up to 20 years.

What can you do?

Stop small infestations before they take over. Burning and mowing are somewhat effective because they allow native and desirable plant to compete with this weed. These two techniques must be repeated for many years to achieve real success because of the longevity of the seeds in the soil and the weeds ability to sprout from broken roots. Hand pulling and cultivation generally are ineffective and time consuming. These two methods will not remove all of the roots and plant will re-sprout from the remaining roots. There are herbicides that are effective. If you have any further questions regarding this weed or other weeds on your property call your local weed district.

Visit the MWCA Weed ID pages for additional information and pictures of Canada Thistle.

This series of articles was developed by Ravalli County. If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Posts related to: Canada Thistle, Cirsium arvense;, noxious weeds, Priority 2B Weed
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Curly-leaf Pond Weed Found in Montana!

Tuesday, July 13th, 2010

In late June, curly-leaf pondweed (Potamogeton crispus), one of Montana’s Priority 1 noxious weeds, was found near Bozeman in several ponds along the East Gallatin River drainage system. Priority 1 noxious weeds have limited presence in the state, and require eradication or containment where they are present, with prevention encouraged in areas not yet infested.

Melissa Graves, Plant Identification Diagnostician from Montana State University’s Schutter Diagnostic Lab, gave a full description of the invasive aquatic plant that occurs in ponds, lakes, and slower moving streams or rivers.

“Curly-leaf pondweed prefers shallow water depths with a silty, high-nutrient bottom. It is distinguished from native pondweed species by its growth habit and distinctive leaf edges. Unlike native pondweeds, it actively grows in winter, with new plants emerging in spring. The leaves have wavy edges resembling lasagna noodles. They are about one to three inches long, narrow, reddish in color, and translucent, with flattened stems visible through the leaves.”

Read the complete article from MSU News Service here.

Visit the MWCA curly leaf pondweed identification page.

Weed of the Week Series – Leafy Spurge

Thursday, July 8th, 2010

Introduction

Leafy Spurge was introduced as an ornamental into the United States in the 1800’s. Presently, leafy spurge covers over 3 million acres in 29 states. It is having major economic and ecological impacts on many western states. These impacts are related to its affect on grazing, wildlife habitat, wildlife related recreation, native plant populations, and ecosystem biodiversity.

Concerns

Leafy spurge is extremely aggressive and can out-compete native vegetation creating monocultures. The milky sap emitted from the stem of leafy spurge is poisonous to humans, horses, and cattle. There are cases where this sap has killed livestock and resulted in blindness in humans. Like livestock, wildlife also avoids grazing spruge. The abundance of leafy spurge in areas historically grazed by wildlife has caused them to migrate into areas they have not before inhabited.

Leafy spurge is having an enormous economic impact on the western states. Montana, North and South Dakota, and Wyoming together spend approximately $144 million per year on leafy spurge control. Land that has been invaded with leafy spurge has a decreased market value because of the plants detrimental ecological effects, as well as, the costs associated with control.

Identification

Leafy spurge has small, inconspicuous green flowers that are surrounded by a pair of yellow-green heart shaped leaves. These leaves are often mistaken for the flower itself. This plant can grow up to 3 feet tall and when the stem is broken milky white sap seeps from it. The leaves that attach to the stem also seep white sap when damaged. These leaves are long and arranged alternately along the stem. The taproot of leafy spurge can be up to 30 feet deep. The seed head on this plant explodes when it is dry, sending the seed up to 15 feet from the mother plant.

What can you do?

Leafy spurge is an aggressive competitor and it takes aggressive management to gain control of infestations. The most successful means of control of leafy spurge have been an intergraded weed management plan that utilizes a combination of methods. There are five methods of controlling leafy spurge, they include: prevention, hand-pulling, biological, revegetation, grazing, and chemical. Prevent infestations by using weed and weed seed free hay, mulch, and gravel. It is also important to prevent the transportation of seeds and root particles on vehicles or clothing. Eradicate small outbreaks as soon as possible. Hand pulling spurge is not the most efficient method, but it can be effective on plants that are in their first year of growth. There are biological controls that have been found to be effective in Montana. They are the flea beetles (Apthona) and root/stem boring beetles (Oberea erythrocephala). Sheep and goat grazing can also be a useful tool when timed correctly and supervised by a knowledgeable herder. Revegetation with competitive plants is always important with any weed control program. All leafy spurge outbreaks take patience and attentiveness to overcome. Have any questions? Call your local county weed district.

Visit the MWCA Weed ID pages for additional information and pictures of leafy spurge.

This series of articles was developed by Ravalli County. If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

Posts related to: Euphorbia esula, Leafy Spurge, noxious weeds, Priority 2B Weed
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Montana Weed Control Association

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Weed Articles

Weed of the Week – Spotted Knapweed

Hoary alyssum–A weed to watch for on your property

Weed of the Week – Common Tansy

Weed of the Week – Blueweed

Weed of the Week – Yellowflag Iris

Weed of the Week – Saltcedar

Weed of the Week – Houndstongue

Weed of the Week – Canada Thistle

Curly-leaf Pond Weed Found in Montana!

Weed of the Week Series – Leafy Spurge

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