Along the Natchez Trace

Sunday, July 13, 2014

We've Been Invaded!

The wildflowers are blooming in profusion here....
Daisys, Brown-eyed Susans, Fireweed, St John'sWort, Bedstraw and on and on and on....They are beautiful and add so much to the fields where the Upland Sandpiper nests.

But along with the native plants, there are other plants that would love to take over...
One that has gotten a toe-hold here is the Spotted Knapweed.  
It's not in flower yet... It's the tall, whitish-green plants you're seeing in among the Birdsfoot Trefoil (yellow).
Following is an article from Wikapedia:

Centaurea maculosa, the spotted knapweed, is a species of Centaurea native to eastern Europe.
It has been introduced to North America,[1] where it is considered an invasive plant species in much of the western United States and Canada.[2] In 2000, C. maculosa occupied more than 7 million acres (28,000 km2) in the US.[2]
Knapweed is a pioneer species found in recently disturbed sites or openings. Once it has been established at a disturbed site, it continues to spread into the surrounding habitat. This species outcompetes natives through at least three methods:
  1. A tap root that sucks up water faster than the root systems of its neighbors,
  2. Quick spread through high seed production, and
  3. Low palatability, meaning it is less likely to be chosen as food by herbivores. It is also suspected to be allelopathic, releasing a toxinfrom its roots that stunts the growth of nearby plants of other species.
Its seed is an achene about a quarter of an inch long with a small bristly pappus at the tip which makes the wind its primary means ofdispersal. The leaves are a pale grayish-green. They are covered in fine short hairs. First year plants produce a basal rosette, alternate, up to 6 inches (150 mm) long, deeply divided into lobes.[3] It produces a stem in its second year of growth. Stem leaves less lobed progressively getting smaller toward the top. The stem is erect or ascending, slender, hairy and branching, and can grow up to three feet tall. Because cattle prefer the native bunchgrass over Knapweed, overgrazing occurs, increasing the density and range of knapweed infestations.[4] Human disturbance is also a major cause of infestations. Knapweed readily establishes itself and quickly expands in all growth forms in places of human disturbance such as industrial sites,[5] along roadsides,and along sandy riverbanks, and also has the potential to spread into undisturbed natural areas.[3]

When we were volunteering here 2 years ago  an effort was made to pull plants up.  Some youth workers from Moosehorn came up for a day...  I think they got several bags full then.  I know Bill & I both spent time pulling, and where appropriate, spraying weed-killer.
It hasn't flowered yet, and so far there are no seed heads to spread.  We try to pull the root system as well.  We use those huge contractor garbage bags to stuff it in...  the plants are either burned (away from the refuge) or left in the bags and go to a landfill.  

It takes a couple of hours to totally fill one of those bags...  but that's about all the longer I can walk around pulling the knapweed before needing a break.  
Since we were here last, we found 2 other areas where the knapweed is now growing.  I suppose it can be spread by birds, by the wind...  or even by vehicles moving through the area.

It would be great if we could eradicate this invasive species - the native plants do not need this competition for their water or nutrients.

But then...
We have a couple of small patches of Crown Vetch...  another invasive species.
We're working on that as well!

Thank goodness we don't have any Purple Loosestrife (that we know of) here on the refuge.  Another pretty plant that just takes over!

That's All For Today!


  1. Didn't they release a special beetle that eats the Purple Loosestrife? I don't see near as much here in MI as I used to.

  2. It always seems like such a loosing battle with those invasives. Good luck!

  3. We are spending this summer in Alaska. Amazed at the wildflowers! Who'd have thought! Not me.

  4. Odd, birds foot trefoil is itself an invasive and no one's going around ripping it out.

    I know, I know. Trefoil has its uses (deer eat it, farmers make it into hay); knapweed just takes up space and crowds out other species. Good luck in trying to eradicate it. It is an extremely tenacious plant.

    I actually think it's kind of pretty in a low-key way. It blooms along the roadsides here at a time when not much else is happening,

  5. You are keeping busy there, fresh air, exercise and having fun too.

  6. If only the desired plants were as hearty as the invasive ones:)