KC Weed News - July 2006
 Topics Below
Summer means boating and swimming but it also means it’s time to keep an eye out for water weeds. Brazilian elodea is not new to our county, but we have only found it in the large lakes – Washington, Union and Sammamish – and two small lakes – Fenwick and Doloff. This means that we really want to know if it is anywhere else. If you are in a lake or slow-moving creek, look for underwater plants with leaves growing in a whorl around the stem (whorl means that leaves all attach at the same point and grow in a circle around the stem). If the stems are really leafy and there are 4 to 8 leaves in each whorl, you may have found Brazilian elodea. Also look for small white flowers with three petals held above the water on slender stems. Our native waterweed (Elodea canadensis) looks similar but is not very leafy, has 3 leaves in a whorl and has even smaller flowers.
The first record of Brazilian elodea in the United States is from 1893 on Long Island and now it is found in almost every state, extending from coast to coast and even to Hawaii. Brazilian elodea is sometimes included in science kits for schools and it is also popular as an aquarium plant under the name Anacharis. Plants are imported without any natural enemies or diseases so they grow vigorously here and can form large dense mats in open water, out-growing native aquatic plants and harming fish habitat and hindering recreation. Many infestations have started from people improperly dumping aquariums into freshwater lakes and rivers. And, like many aquatic plants, Brazilian elodea spreads easily by fragments and moves from lake to lake on boats and trailers.
Our aquatic weed specialist will be looking for new populations of Brazilian elodea in the county’s lakes and waterways. The key to stopping the damage caused by this plant is to find it early. Once an aquatic noxious weed such as this one are established in a river or lake it can cost many thousands of dollars a year to simply reduce its impact. In many cases, eradication may not even be possible once the population has spread beyond its initial area of introduction.
Please contact the King County Noxious Weed Program at 206-296-0290 if you think you see Brazilian elodea growing in a lake or stream in the county. Identifying aquatic plants is very technical, so please contact us before you begin any control efforts. For more information on identification, also check out the Department of Ecology information on Brazilian elodea and our native elodeas.
Weeds in Bloom: Noxious Weeds to Look For in July
Going to Seed : Milk Thistle, Dalmatian Toadflax, Yellow Hawkweed, Orange Hawkweed, Common Hawkweed, Meadow Knapweed, Sulfur Cinquefoil, Giant Hogweed, Goatsrue,
Flowering Now : Tansy Ragwort, Policeman’s Helmet, Spotted Knapweed, Spanish Broom, Perennial Pepperweed, Diffuse Knapweed, Purple Loosestrife, Garden Loosestrife, Perennial Sowthistle, Rush Skeletonweed, Scotch Thistle,Common Bugloss
Will Flower Soon: Hairy Willow-herb, Brazilian elodea, Common Reed, Floating Primrose-willow
King County Fair - Weed Booth and More
Come join us at the King County Fair at the fairgrounds in Enumclaw from July 19 to July 23. We will be displaying many of the county’s noxious weeds at our booth and we will be there to answer all your noxious weed questions. Look for us outdoors in the West Midway section just down from the kiddie rides and across from the Rabbit Barn. Also, check out the county’s mini park complete with a trail and even a noxious weed or two to show the problem of noxious weeds in our parks.
Program in Review - 2005 Annual Report
Midway through 2006, it is a good time to reflect on the progress we made last year and the work still left to be done. Our program’s 2005 Annual Report is complete and being distributed on request. We have also put the report and all of its appendices on our web page for those who prefer to read it online or print their own copy.
We have made great progress on reducing the impacts of Class A and B noxious weeds but there is still significant work to be done. Although we have been able to reduce the area infested by Class A noxious weeds such as giant hogweed and garlic mustard, we continue to find new populations and eradicating large established infestations continues to be highly challenging. Our strategy for Class B noxious weeds like tansy ragwort and purple loosestrife is to reduce their impact and prevent their spread and overall we have been able to achieve that. The overall number of infestations continues to rise, however, as we find new sites, and existing populations continue to persist. Noxious weed control is clearly a moving target that requires considerable commitment, coordination and resources. Fortunately, more than 99% of the property owners we work with are willing to control their Class A and B noxious weeds voluntarily. King County is fortunate to have a citizenry that is concerned about the environment and willing to help fight the spread of invasive plants.
County Knotweed Projects are Up and Running
We are very fortunate to have been awarded funding once again from the US Forest Service Forest Health Protection program ($31,200), US Forest Service Title II ($8,500) and the US Fish and Wildlife Service ($25,000) to continue with our fight against knotweed on the Green River and the Skykomish River. In addition, we are able to add a knotweed control project on the Middle Fork of the Snoqualmie River due to a successful request for funding from the WSDA Knotweed Program ($15,000). In all of these projects, we are fortunate to be working with great partners and property owners willing to participate and coordinate in this effort against the spread of knotweed on the county’s rivers.
Our knotweed project manager Monica Walker has begun her initial survey of the knotweed treatment areas, and the results from last year are encouraging for the most part. The stem injection method continues to be the most consistently effective method. She will change our foliar treatment strategy to include imazapyr as well as glyphosate as a result of less than satisfactory control on some sites treated with triclopyr or glyphosate alone. Monica also plans to include digging up rhizomes in some isolated areas where there continues to be a small amount of regrowth in spite of foliar treatment. One thing is clear – knotweed is perhaps the most difficult plant to eradicate and one of the biggest threats to our county’s riparian areas. Our work has only just begun on this challenging weed and we will need to continue to gather resources and coordinate efforts if we hope to combat this plant county-wide.
Maple Valley Knotweed Biology and Control Workshop
We are holding a public workshop on knotweed for the residents of Maple Valley on August 8 from 6:30 pm to 8:00 pm. The workshop will be at the Lake Wilderness Lodge in the upper conference room and out in the wetland area. We will cover the basic biology of invasive knotweed species and hybrids and the different methods used to control this plant, including demonstration of some of the methods. If you would like to attend, please contact Diana Pistoll at the City of Maple Valley to register or contact Sasha Shaw at 206-263-6468 for more information.
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