Download Purple Loosestrife

Distribution of Lythrum salicaria
Origin(s)
• Native to Europe and Asia
• Possibly introduced as seed from ship ballast in
1800s on east coast
• Sheep wool?
• Probably introduced in nursery trade as an
ornamental or medicinal plant
• In 23 states and 9 provinces currently declared
as officially
Noxious
Identification & Taxonomy
• Lythraceae
• Variable growth
form
– Leaves opposite or
alternate
– Stem glabrous or
pubescent
• Many ornamental
varieties
Biology
• Germinate on moist open
(=disturbed) soils
• Tolerate wide range of growing
conditions such as moisture,
substrate, pH (=generalist)
• Long-lived (=perennial)
• Mature plant produces 2.5
million seeds/yr that are viable
in seed bank for years
Ecological Impact
• can produce near monoculture leading to
loss of native biodiversity
• harms waterfowl nesting habitat
• negative impacts on some amphibians and
algal communities
• reduces water flow and quality
• inhibits transportation
• degrades hunting and fishing areas.
Control
• Chemical
– herbicides-must be approved for use around water
– provide short-term control of small infestations or isolated plants,
but may be impractical and uneconomical against large
infestations.
• Mechanical
– pulling small, individual plants is feasible; pulling large plants is
very difficult.
– plowing or disking small infestations is also possible, but will
require repeated treatments as plants will sprout from cut root
pieces. Plowing large infestations is difficult and generally
ineffective.
– mowing, burning, and flooding can be effective management
strategies, but are difficult, expensive, and time-consuming, and
may have severe negative, long-term consequences for wetland
communities.
• Biocontrol
Biocontrol
• No potential herbivores in North America
• >100 associated insects found in Europe, 9
evaluated
– some also fed on non-target natives, Lythrum alatum
and Decodon verticillatus (Swamp Loosestrife)
– further invasion by L. salicaria considered a greater
threat
• Other flower or seed eating predators
considered
Natural Enemies
Leaf feeders: Galerucella calmariensis & G. pusilla
Coleoptera: Chrysomelidae
Larvae produce diagnostic “shothole” damage
Natural Enemies
Root feeder: Hylobius transversovittatus
Coleoptera: Curculionidae
Root damage
Stem damage
Natural Enemies
Flower feeder: Nanophyes marmoratus
Coleoptera: Cucurlionidae
Culturing Beetles
Life Cycle and Timing