Bad Daisies

Oxeye_Daisy_TaylorCanyon_2008jul14_LAH_006-001Fresh as a daisy. Daisy chains. “The daisy’s for simplicity and unaffected air.”*

Symbols of simple charm, it’s hard to imagine that daisies could be anything but pure and innocent. Yet, the familiar Oxeye daisy has a dark side. Under that attractive and cheerful guise lurks… a noxious weed!

Take a trip to the mountains to see the wildflowers, and you’re bound to see Oxeye daisies as well. They’re all over the Rockies, preferring the higher elevations. Unfortunately, they don’t belong here. They’re native to Europe, and we heartily wish they had stayed there!

Unfortunately, such a pretty flower was bound to get around. The species was initially imported as an ornamental, and seeds can still be found occasionally in wildflower mixes.

Oxeye_Daisy_TaylorCanyon_2008jul14_LAH_008Just as with other criminals at large, the oxeye goes by several aliases: white daisy, field daisy, and Marguerite are a few. A selected horticultural strain is named ‘May Queen.’ There’s even confusion over the scientific name; botanists know it as either Leucanthemum vulgare or Chrysanthemum leucanthemum.

Different counties in Colorado have different laws regarding control and eradication, but all agree that oxeyes are a serious problem. According to the Colorado Department of Agriculture,

Oxeye daisy is designated as a “List B” species in the Colorado Noxious Weed Act. It is required to be either eradicated, contained, or suppressed depending on the local infestations.

Still, it’s hard to take daisies seriously. Why are they so bad? Three issues…

  1. Animals don’t like to eat them. Domestic animals such as cattle avoid browsing on the plants. They don’t even like to walk through a patch of daisies, as the plants irritate their faces and legs. Wild animals won’t eat them either. And since no one is munching on them, the infested areas spread wider and wider, crowding out plants that do provide food. It’s a vicious cycle.
  2. Oxeyes are aggressive and hard to kill. The plants are perennials, and they’re connected underground by a network of rhizomes which can send up new rosettes. They also make a lot of seeds. A plant typically produces two- to four thousand seeds per season. (As if that isn’t enough, scientists have documented a high of 26,000 seeds from just one plant!) If those seeds don’t germinate right away, one study showed that 86% of them are still viable six years later.
  3. These daisies have a shallow root system, which creates areas of bare ground, increasing soil erosion.

Controlling an infestation requires a continual effort over many years. Repeated mowing removes flower stalks before they can set seed. Hoeing or hand-pulling can remove crowns, but more digging is needed to get the rhizomes. Sheep and goats will eat the plants, and are particularly useful in hard-to-access areas. Chemical weed killers (such as 2, 4-D, picloram, and Transline®) can be effective but will kill other broad-leaved plants as well, and have other environmental concerns.

Prevention is often the best approach. Bare ground invites weeds. Seeding with a weed-free wildflower or forage mix shades the soil and keeps daisy weeds from germinating.

Leucanthemum x superbum_Shasta Daisies _XG_LAH_7067Thankfully, not all daisies are villains. Although the oxeye is one of the species Luther Burbank used in creating the popular Shasta Daisies (left), cross-breeding has tamed its invasive nature. Choosing one of the many well-behaved Shasta cultivars allows us to include daisies in our gardens—and every garden needs daisies!

_____
*Robert Burns

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3 Responses to Bad Daisies

  1. Karin says:

    Do you know if Oxeye Daisies are noxious in WA, too? I know we have some Shasta ones. They are so pretty!

  2. LAH says:

    Yes, they are. They’re on the “C” list, which means it’s pretty much hopeless, but you should try to contain any oxeye daisies on your property. Shastas are perfectly fine. See http://www.nwcb.wa.gov/searchResults.asp?class=C for the “C” list, and http://www.nwcb.wa.gov/nwcb_nox.htm for an explanation of your noxious weed policy.

  3. Pingback: Delinquent Daisies | Mountain Plover

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