Purple Loosestrife

1
Purple Loosestrife

• The Beautiful Invader
• Sharon Gillies Alida Janmaat

2
Purple loosestrife is easy to identify when in
blossom.
3
Winter
Spring
Fall
Summer
Location All Herb Species Native Herb Species Exotic Herb Species All Shrub Species Native Shrub Species Exotic Shrub Species
Langley 8-256 St 0.649 0.852 0.498 0.479 0.609 0.224
Langley 16-224 St 0.703 0.630 0.559 1.337 1.352 0.163
Langley 58-264 St 0.989 0.853 1.132 0.664 0.597 0.5
Langley 60-264 St 0.438 0.354 0.3531 0.584 0.565 0
Chilliwack Great Blue Heron 1.132 0.563 0.953 1.244 1.067 0.169
4

• 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 (Lythrum salicaria L.)

5
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/in
fo/loose2.htm
6
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.
Location All Herb Species Native Herb Species Exotic Herb Species All Shrub Species Native Shrub Species Exotic Shrub Species
Langley 8-256 St 0.649 0.852 0.498 0.479 0.609 0.224
Langley 16-224 St 0.703 0.630 0.559 1.337 1.352 0.163
Langley 58-264 St 0.989 0.853 1.132 0.664 0.597 0.5
Langley 60-264 St 0.438 0.354 0.3531 0.584 0.565 0
Chilliwack Great Blue Heron 1.132 0.563 0.953 1.244 1.067 0.169
7
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
8
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.
9

• 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

10
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)
11
Purple LoosestrifeHow can we control it?

• Biological Control
• Best for severe purple loosestrife infestation
  (gt3 acres)
• Works by using a plants 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 calmariensis and Galerucella pusilla
  , two leaf eating beetles
• Nanophyes marmoratus , a flower feeding weevil

http//www.ducks.ca/purple/faq/index.html - No.4
12
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

13
Research

• Alida Janmaat is conducting research on
  biological control of purple loosestrife in the
  Fraser delta.
• Sharon Gillies, Alida Janmaat, and Steve Marsh
  are collaborating by measuring water quality in
  the Fraser River as part of the Woods Hole
  Oceanographic Institutes Global Rivers Project
• http//www.whoi.edu/page.do?pid19760