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Purple Loosestrife. The Beautiful Invader Sharon Gillies + Alida Janmaat. Purple loosestrife is easy to identify when in blossom. Winter. Spring. Fall. Summer. Introduced as a horticulture plant, it has become a problem in many areas.
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Purple Loosestrife The Beautiful Invader Sharon Gillies + AlidaJanmaat
Purple loosestrife is easy to identify when in blossom. Lessoning Loosestrife
Winter Spring Fall Summer Hard to ID the rest of the year
Introduced as a horticulture plant, it has become a problem in many areas. • In the summer of 2007 an extensive survey of Langley, Abbotsford and Chilliwack was conducted to GPS map the distribution and abundance of purple loosestrife (Lythrumsalicaria L.)
Purple LoosestrifeWhere does it live? • Moist soil to shallow water • Wet meadows and pastures • Marshes and wetlands • Stream and river banks • Lake shores • Roadside ditches • Can tolerate drier conditions • Lawns and gardens • Agricultural and pasture land http://www.dnr.state.wi.us/org/land/er/invasive/info/loose2.htm
Spreading in the Fraser Valley Our survey found purple loosestrife in wetlands sites which had been disturbed by human activities (dredging, etc.). When compared with a survey completed in 1992 where 7 sites were identified in this area, we found 108 purple loosestrife sites. We did not find any large single species stands of purple loosestrife. Problem areas in the Fraser Estuary – in particular in brackish areas.
Purple LoosestrifeWhat does it do? • Invades wetlands • Out-competes and replaces native plants • Eliminates natural food and cover for wildlife • Can change the structure and function of a wetland • Affects humans • Can clog irrigation systems • Possible uses • Provides a nectar and pollen source for bees www.uq.edu.au/nanoworld/ images/honeybee-1.jpg
Crowding out native species in BC? In our study, 18 species could only be found in areas where purple loosestrife was not present. Our data may indicate that some species are rare in disturbed wetland sites, and the presence of purple loosestrife may increase their rarity.
The ability of purple loosestrife to crowd out native species may put some species at risk. • We should remove it from wetland areas and prevent the spread of this invasive plant
Purple LoosestrifeHow can we control it? • Manual (digging, pulling, cutting) • Not effective for large infestations • Difficult and time consuming. Must follow up annually when new plants appear. • Remove as much of root system as possible and dispose of plants properly Cutting Stalks Credit: MJ Kewley Org: Great Lakes Indian Fish & Wildlife Commission (GLIFWC)
Purple LoosestrifeHow can we control it? • Biological Control • Best for severe purple loosestrife infestation (>3 acres) • Works by using a plant’s natural enemies against it • After years of testing to be sure the species would not negatively impact wetlands and agricultural crops, three species [imported from Germany!] were approved for use in control of purple loosestrife: • Hylobius transversovitta tus, a root mining weevil • Galerucella calmariensisand Galerucella pusilla , two leaf eating beetles • Nanophyes marmoratus , a flower feeding weevil http://www.ducks.ca/purple/faq/index.html - No.4
Purple LoosestrifeWhat can we do to help? • Report locations where purple loosestrife is found • BC Report-A-Weed • http://www.for.gov.bc.ca/hra/Plants/raw.htm • Request your local garden center or nursery to stop selling purple loosestrife if you find it there • Replace purple loosestrife with native plants in ornamental gardens
Research • AlidaJanmaat is conducting research on biological control of purple loosestrife in the Fraser delta. • Sharon Gillies, AlidaJanmaat, and Steve Marsh are collaborating by measuring water quality in the Fraser River as part of the Woods Hole Oceanographic Institute’s Global Rivers Project • http://www.whoi.edu/page.do?pid=19760