Giant knotweed keeps coming up

Wallace Kaufman pauses on the battlefield

Wallace Kaufman pauses on the battlefield

Wallace Kaufman and Knot-weed stalks

April 24, 2015. Along the west bank of Poole Slough, 4 miles east of the Pacific Ocean and Newport, OR.  Here begins the first battle of the third year against the dense stand of giant knotweed that took over about an acre of land where an old barn and a few apple trees stood 60 years ago. When the first battle began in late summer 2012 the knotweed stood in an almost pure stand, stalks up to 10 feet high and two inches thick, two or three stalks from one root, plants 6 to 12 inches apart. Although I cut before they flower, the roots send out new stalks all summer and again in the spring. The stalks are hollow cylinders closed off at knots every 6 to 12 inches. Dried stalks make good pan pipes and flutes. Fresh young stalks can be peeled and cooked as vegetables.

Since the plants begin storing carbohydrates in the roots in early summer, I’ll cut again then and again in the fall. As the lower growing natives begin to compete, the prospects are that I can begin regular mowing with a blade set high to allow low natives to grow while preventing the knotweeds from replenishing their roots.

Each year the stand has been slower growing, stalks slimmer, and height diminished. Here is a scene from the very first attack 3 years ago.

 

 

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Water hyacinth used for counteracting algal blooms

In a controversial experiment in Florida, researchers are stocking King’s Bay with floating pens of water hyacinth (Eichornia crassipes) to reduce algal blooms.  Water hyacinth was removed from the bay beginning in the late 1950s, but Hydrilla replaced it and now algal blooms have become an issue in the lake.  Water hyacinth is good at removing pollutants from water and shading out algae.  In addition, manatees love it!

The pens also contain two other non-native species (called native in the original article), water lettuce and frog’s bit, considered less invasive by the some, but the article does not address whether these two plants would serve the same function as the water hyacinth.

Read more at the University of Washington’s Conservation web site and for updates see the Florida Springs Institute.

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Invasive species threat to Federally endangered species

A government report on invasive species’ impacts on threatened and endangered species finds that the topic has not been well researched in most cases.  As I’ve been looking for reports on invasive plant impacts to threatened and endangered species in Maryland I’m inclined to agree!

Find the full report at: http://www.cabi.org/Uploads/isc/Systematic%20Review.pdf

What is the evidence that invasive species are a significant contributor to the decline or loss of threatened species?  Philip D. Roberts, Hilda Diaz-Soltero, David J. Hemming, Martin J. Parr, Richard H. Shaw, Nicola Wakefield, Holly J. Wright, and Arne B.R. Witt

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Updated Michigan guide to Phragmites control

Michigan’s A Guide to the Control and Management of Invasive Phragmites has recently been updated.  This 3rd edition has expanded content on how to distinguish between the native and European strain of Phragmites and new recommendations on treatment strategies.

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Forest Fragments in Managed Ecosystems Study – Invasive plant habitat projects

At the Delaware Invasive Species Conference this week two Delaware researchers presented some preliminary findings from research done through the FRAME long-term ecosystem study in northern Delaware.  Ph.D. candidate Solny Adalsteinsson is finding more ticks under multiflora rose than uninvaded areas 25 meters away.  However, uninvaded forest fragments had more ticks than invaded fragments did overall.  She is currently collecting data on Lyme disease infection prevalence and tick burdens on mice.

Dr. Greg Shiver studies birds in the FRAME fragments.  He is looking at whether there is a link between invaded sites and the lack of calcium-rich prey important for breeding birds.

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Insect feeding on Buddleja

Researchers in the Netherlands have posted some preliminary data on insect feeding on invasive Buddleja davidii shrubs compared to native species demonstrating that there is less insect feeding on the leaves, http://eco-restore.net/2014/09/29/is-buddleja-davidii-important-food-resource-for-leaf-herbivores-in-quarries/#more-316

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Value of weedy plants as forage

Utah State University Extension has a nice publication summarizing the forage value of a number of noxious weeds and a summary of toxicity reports of many of the plants at the end.  The report was written by Beth Burritt and Rae Ann Hart and published in May, 2014.  There’s a lot of research that still needs to be done on these plants, but it could be a good first guideline if you are interested in using grazing animals to control invasive plants.

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Composting invasive plants

Composting invasive plants has to be done carefully to fully kill seeds and other potential propagules.  Researchers in Texas built a composting facility to handle wetland invasive plants and report on their experience in an article in Invasive Plant Science and Management.  Wouldn’t it be great to turn those invasive plants into compost to raise native seedlings?

Erica J. Meier, Tina M.Waliczek, & Michael L. Abbott. 2014. Composting Invasive Plants in the Rio Grande River. Invasive Plant Science and Management, http://www.wssajournals.org/doi/abs/10.1614/IPSM-D-13-00089.1

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