Gov. John Hickenlooper has signed a proclamation declaring July 7-13 as Colorado Weed Awareness Week. The Colorado Department of Agriculture works to stop the spread of noxious weeds across the state through a coordinated effort to detect and eradicate new invaders as well as manage well-established species. Currently, there are 74 species of plants in the state that are designated "noxious," meaning they pose a threat to the state's agricultural productivity, wildlife habitat and native plant communities.
This month, we feature an aggressive noxious weed that competes with pasture forage and high meadow native plant communities: Oxeye daisy.
FACT SHEET & MAP: www.colorado.gov/ag/oxeyedaisy
LOCATION: Oxeye daisy typically grows in higher elevations in Colorado, from the foothills to near timberline. Large populations can be found on ski area slopes, mountain roadsides and high meadows. It is estimated to spread from 15-25 percent per year if not controlled, reproducing both by seed and underground rhizomes.
TREATMENT: The key to effective control of oxeye daisy is education and prevention. It has been included in many different seed mixes, thus consumers should carefully read the label prior to planting so called “native wildflower” mixes. Digging or pulling is ineffective unless all of the plant’s creeping root system can be removed. Small populations can be diminished by repeated pulling. Herbicides are effective in dense stands where native plants won’t be harmed. Oxeye daisy produces an average of 500 seeds per plant which are viable in the soil for 2-3 years and have a very high germination rate. Treated sites must be monitored for at least 10 years after the last flowering adult plants have been eliminated and treatments repeated when necessary.
BACKGROUND: Oxeye daisy was introduced from Europe as a seed contaminant and as an ornamental. It is an erect, rhizomatous, creeping perennial that grows 10 inches to 2 feet tall. The basal and lower leaves are lance shaped and toothed with leaf stems and the upper leaves are narrower and clasp the stem. The leaf size progressively decreases up the stem. Flower heads are mostly solitary at the end of the flower stalk and the flower head has 15 to 30 white ray petals. Oxeye daisy is often confused with a lookalike - Shasta daisy, a popular ornamental that has larger flowers (greater than 2 inches in diameter), grows 6-12 inches taller and is a many-stemmed plant.
WHAT YOU CAN DO: If you see this plant, please contact your county weed management program or CDA. County weed programs are a tremendous resource for treatment information and management of specific weeds in specific counties. Find your county contact at www.colorado.gov/ag/coweedcontacts. You can also email CDA at Steve.Ryder@state.co.us.
WEED AWERENESS WEEK: A number of activities are scheduled during Colorado Weed Awareness Week. Many communities will be holding “Pulling for Colorado” events, where local volunteers gather to learn about noxious weeds, then tackle a nearby noxious weed problem area. For a map of 2013 events, visit www.cwma.org/p4c. Additionally, in the Denver area, Barr Lake State Park will be hosting a combined Weed Awareness and Lake Appreciation Day, with volunteer projects in the morning, and fun events for all participants in the afternoon. Contact the Barr Lake Nature Center for details (303) 659-6005.