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Weed of the Week


Nov 10

Field Bindweed (Convolvulus Arvensis)

Posted on November 10, 2014 at 3:38 PM by Eric Brown

Field Bindweed

Overview
Field Bindweed is the bane of many Colorado gardeners. It is a vine-like, creeping perennial that spreads thickly over the ground, and can quickly climb and smother desirable plants. It is also poisonous to horses. Flowers are white or pink, bell shaped, and have the characteristic Morning Glory appearance. Leaves are alternate, 1-2 inches long, and somewhat arrow-shaped, although there can be great variation in leaf shape, even on the same plant.

Field Bindweed is one of the most competitive perennial weeds in Colorado, and is very common in our area. A 2 or 3-year food supply is stored in the root system, making this plant very difficult to kill. In addition, seeds can remain viable in the soil for over 40 years. It is best to eliminate young bindweed plants before they have a chance to set seed or develop their extensive root system.

For information about herbicide control of these and other noxious weeds, contact the Garfield or Pitkin County weed control program.

A mite is currently available from the CSU Insectary in Palisade Colorado. Landowners can order mite releases directly from the Insectary for $35 per release. Call 970-464-7916 for more information. In addition, Pitkin County has a number of releases available for redistribution to Pitkin County residents on a first-come, first-served basis. Contact Pitkin County Land Management soon to reserve your mites!

Garfield County, in cooperation with the local Conservation Districts, and Pitkin County both offer cost-share programs that provide financial assistance to landowners for noxious weed management.

For additional information:
Nov 10

Absinthe Wormwood (Artemisia Absinthium)

Posted on November 10, 2014 at 3:34 PM by Tim Weideman

Absinth Wormwood Artemisia Absinthium

Overview
One of the newer weeds to enter the noxious weed radar screen is absinthe wormwood. The introduction of absinthe wormwood to North America was deliberate and related to its potential uses as a medicinal and as an ingredient in the liquor, absinthe. Absinthe wormwood is a native of Eurasia, the Middle East, and North Africa.

In North Dakota it was first reported in 1910 and by 1973 a state inventory reported 40,000 acres in 42 of 53 counties. In 63 years absinthe went from a rarely seen plant to 1 designated as a noxious weed and present in the majority of the state of North Dakota.

Absinthe wormwood is an aggressive perennial plant and is now on the State of Colorado’s and Pitkin County’s noxious weed list. By state law, this plant must be eradicated in the Crystal River Valley and is found from Marble to Carbondale.

It is common in the Missouri Heights area of both Garfield and Eagle counties. It is similar in its shrub-like appearance to our ecologically important, native big sagebrush species and consequently is commonly overlooked. Its leaves are a similar sage, blue green color and the plant habit is comparable to our native big sages with heights reaching 16 to 48 inches.

One way to tell the difference: our native sages are woody and have leaves that persist over the winter. Absinthe is an herbaceous species that dies back to the root crown each fall and regrows from the soil level each spring. Garfield County, in cooperation with the local Conservation Districts, and Pitkin County both offer cost-share programs that provide financial assistance to landowners for noxious weed management.

To learn more about invasive ornamentals, please attend Pitkin County’s annual Ornamental Weed Tour in Snowmass Village on July 8 from 9 a.m. - Noon. The event is free and lunch will be provided. RSVP by emailing Crystal Yates or calling 970-920-5214.

For additional information:
Nov 10

Oxeye Daisy (Chrysanthemum Leucanthemum) & Scentless Chamomile (Matricaria Perforata)

Posted on November 10, 2014 at 3:32 PM by Tim Weideman

Don’t Be Fooled!
Many of those perky white daises are invaders, not native wild flowers. While there are native white daisies in Colorado, the most common ones you will find this summer are actually Noxious Weeds. Oxeye Daisy and Scentless Chamomile were introduced as ornamentals but have escaped cultivation and are now moving into native habitats. These aggressive invaders displace important wildlife forage, reduce available habitat, and disrupt the delicate balance of riparian ecosystems.

Oxeye Daisy (Chrysanthemum Leucanthemum)
Oxeye Daisy Chrysanthemum Leucanthemum

Oxeye Daisy grows as an erect perennial with a fibrous root system. Showy white blossoms have yellow centers. Lower leaves are spoon-shaped and appear somewhat waxy; upper leaves are narrow, deeply lobed, and clasp the stem. Oxeye Daisy is often confused with the non-noxious ornamental Shasta Daisy. However, Shasta Daisy leaves are much larger and are not lobed but have serrate edges.

Scentless Chamomile (Matricaria Perforata)

Scentless Chamomile (Matricaria Perforata)

Scentless chamomile is an annual that grows .5-foot to 2-feet tall in a bushy shape with showy white daisy flowers. It is nearly identical in appearance to the variety used for tea, but can be easily distinguished by its lack of odor. Scentless chamomile has no forage value and can cause blistering of muzzles, irritation of mucous membranes, and skin rashes in livestock and wildlife. A single plant can produce as many as a million seeds.

These are just 2 of several Escaped Ornamentals now invading the Roaring Fork Valley. To learn more about invasive ornamentals, please attend Pitkin County’s annual Ornamental Weed Tour in Snowmass Village on July 8 from 9 a.m. - Noon. The event is free and lunch will be provided. RSVP by emailing Crystal Yates or calling 970-920-5214.

Pitkin County is offering $20 coupon to Crystal Gardens or Planted Earth, in exchange for a 13-gallon trash bag full of certain noxious ornamental weeds. Qualifying weeds include Oxeye Daisy, Dame’s Rocket, Scentless Chamomile, Absinthe Wormwood, Myrtle Spurge, and Houndstongue. Limit 2 per person. Pitkin County residents only. Bring your 13-gallon trash bag full to the Pitkin County Landfill to exchange for your coupon.

Garfield County, in cooperation with the local Conservation Districts, and Pitkin County both offer cost-share programs that provide financial assistance to landowners for noxious weed management.

For additional information: