Oxeye daisy (Leucanthemum vulgare) is a perennial, herbaceous, non-native plant growing 1 to 3 feet tall with showy white flowers. It was introduced from Europe as an ornamental plant and as seeds contaminating cereal crops. It has spread profusely across the world and is a non-native in 40 countries and every state in the U.S. Oxeye daisies survives in a wide variety of soil types, climates, and other environmental conditions. Frost and drought do not affect this plant.
Oxeye daisy has 2 growth periods – spring and fall — and germination occurs throughout the growing season. The report from the Washington State Noxious Weed Control Board states 90-95% will germinate at 68 degrees F. Fall is when most seedlings establish. First year plants will remain in the rosette stage until after a cold winter which initiates blooming. It is the rosette stage that certain foliar herbicides can be applied effectively.
On average a plant can produce 1,300- 4,000 seeds and large, hearty plants have yielded up to 26,000 seeds (Howarth and Williams 1968)! These seeds are highly viable and can remain so up to 39 years although the percentage of viability drops after 6 years. Champness and Morris (1948) found one million seeds per 2.5 acres in ag fields and up to 4.2 million seeds per 2.5 acres in grasslands.
The above photo shows the myriad of seedlings that can be found. This is about a 4″ diameter area.
The photo to the right shows how the first year rosettes are clustered at the base. All these small seedlings are critical to get removed!
Oxeye daisy spreads by seeds, by rhizomes, and by adventitious roots. The roots are shallow and grow rapidly, forming a dense mat that leaves no space for the native plants. If you pull up a large clump, it creates a good deal of soil disturbance as well as a shallow hole. Often when hand pulling, the individual stems easily break off from the main clump. If you leave one stem, you’ll be back again!
These 3 photos show how the adventitious roots and the curving stems are big advantages to this plant. It sure makes it challenging to remove them. When they are intermingled with native plants, one has to go to the base of the plant, gather up all the stems and pull from there. Then one must double check as it’s nearly certain a stem was missed (at least that’s been my experience)!
How to Control Them
Control must be done immediately as these plants can spread rapidly. You will need a strategy that uses a combination of herbicide and hand pulling to be effective.
Herbicide
Ox eye daisies are resistant to many herbicides, but I have had good luck with Garlon 4 in bark oil on first year plants in the rosette stage. When searching for these, be sure to scan the area around a rosette – where there’s one, there’s probably 2 or more! I’ve used herbicide successfully with the large clumps, too, but it’s much more work than spritzing a rosette. I gather all the bowed out stems, untangling them from the native plants, cut them low to the ground and spritz the root crown.
Hand Pulling
Once in bloom, hand pulling is the best control with the caveat that one must get all the seedlings around it. If you miss one of those stems that has curved out and away from the initial group, you’ll have that plant back next year. Fortunately, the stems are easy to identify even when intertwined amidst native plants since they have an interesting purple striped pattern.
Mowing
Mowing does not successfully kill oxeye daisies. It can be used as a triage method to prevent the bloom from setting seed, but the plant will survive and bloom again only at a height short enough the mower blades can’t reach it.
Grazing
Grazing is not very effective. Horses, sheep, and goats will eat oxeye daisy and the viability of the seed is reduced when passing through the animal, but it is not killed. Cows and pigs generally avoid oxeye daisies. If a milk cow does eat it their milk has an off flavor to it.
Fire
Prescribed burns aren’t effective either. The disturbance and open spaces resulting from burns make this management tool ineffective and could lead to further infestation.
One last word of caution – if you’re buying pre-mixed, pre-packaged seed Ox eye daisy could be in the mix. Be sure you know each species in the mix and source your seeds from a company specializing in native plant restoration. I’m not an advocate of any mixes but definitely do not purchase mixes from big box stores.
References
Champness, S.S. and K. Morris. 1948. The population of buried viable seeds in relation to contrasting pasture and soil types. Journal of Ecology 36: 149-173.
Howarth, S.E. and J.T. Williams. 1968. Biological flora of the British Isles. Journal of Ecology 56: 585-595.
Washington State Noxious Weed Control Board. 2000. Written findings of Leucanthemum vulgare. www.nwcb.wa.gov/siteFiles/leucantheum_vulgare.pdf. Accessed 04 June 2016