Noxious Weed Spotlight - Oxeye Daisy
By: Shelly L. Simmons, Purgatoire Watershed Weed Management Collaborative
ssimmons@tamariskcoalition.org or 719.469.2847
If you live in the Upper Purgatoire Watershed, you may have noticed a prolific white flowered plant, resembling a daisy, infesting meadows and roadsides this year. This is oxeye daisy, a noxious weed overtaking hundreds of acres in the upper watershed. This plant is aggressive, forming spreading clumps which out-compete native plants. It is unpalatable to livestock and wildlife, drastically reducing forage value as it spreads.
Be aware: Oxeye daisy is often included in "wildflower seed mixes". Do not plant wildflower seed mixes unless you know and can verify the species in the mixes will not escape cultivation and become a noxious weed.
Oxeye daisy forms an extensive, dense, shallow root system. This ultimately creates areas of bare soil and increases soil erosion. Mowing and cultivating are not generally good control techniques, as the plant can re-sprout from root fragments. Seed viability is 38 years or longer. Any control program must include at least 10 years of monitoring and treatment of any re-sprouts or seedlings after the last flowering plant has been eliminated.
Oxeye daisy is often confused with Shasta daisy. However, Shasta daisy is not an aggressive invader. It is 6-12 inches taller and has large flower heads.
Key ID Points
1. 15-30 white ray flowers on flowerheads that are 1-3 inches in diameter.
2. 6-10 inches tall.
3. Rosette and lower leaves are spoon-shaped and toothed.
4. Upper leaves on the stem are narrow, toothed, and clasp the stem.
5. Grows at higher elevations, up to 11,000'.
Key Management Techniques
1. New infestations (i.e. only a few plants) can be mechanically removed by digging down six inches or more and removing the entire root system.
2. Once the infestation has reached more than a few plants, chemical control is the most effective control.
3. The following treatment table is from the Colorado Department of Agriculture: