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PURPLE LOOSESTRIFE: WEED IT OUT!
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| It chokes wetlands, rendering them
inhospitable to native plants and wildlife. Known as the "purple
plague," this invasive plant unfortunately is still sold for
landscaping. A hardy European native graced with stunning spikes of
purple flowers, purple loosestrife (lythrum salicaria) was first brought
to NE in the early 1800’s, most likely as an ornamental. After its
introduction, the plant moved rapidly north into Canada, south into Va.
and west through the Great Lakes, earning it the nickname, "the
purple plague." This alien now exists throughout much of the US; it’s
an especially serious threat to wetlands in the Northeast and upper
Midwest. |
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| Its swift growth and enormous
reproductive capacity allow it to spread rapidly and outcompete native
plants. Mature loosestrife propagates vegetatively by root or stem
segments. Also, each plant can produce millions of tiny seeds that are
carried along by wind and water to establish new populations. As a
result, many wetlands once inhabited by a rich diversity of native
plants are now overrun by dense stands of purple loosestrife, stands
that can grow enormously, eliminating open water habitat. The loss of
native species and habitat diversity is a significant threat to wildlife
that depend upon wetlands for food and shelter.
It’s still sold commercially, despite its devastating and
well-documented communities. It’s promoted by horticulturalists
for its beauty as a landscape plant and by beekeepers as a nectar plant.
Some nurseries sell cultivated varieties of purple loosestrife that are
reportedly infertile, but studies have shown that the plants are fertile
and can cross with wild strains of loosestrife. Some states have listed
it as a noxious weed and prohibit its importation and distribution. In
many other states plant societies are raising public awareness of this
aggressive invader and urging that its sale be banned.
Its rapid spread across North America has been aided by the absence
of its natural predators: herbivorus beetles that keep the plant in
check by feeding on its roots and leaves. Like loosestrife, the beetles
are native to Europe. Herbicides and hand removal may be used in
controlling individual plants or small populations. Carefully selected
biological controls, such as natural diseases or predators that are
specific to the invasive pest species, are consider to be a potential
long term management strategy.
Because it’s extremely difficult to control once established, the
best defenses against the weed are detecting it early and preventing its
spread. We must focus on keeping natural wetlands free from human
disturbance; even minor disruption can make them highly vulnerable to
the "purple plague’s" invasion. Keeping informed
about the dangers of purple loosestrife and discouraging its use in
landscaping are other keys to deterrence. |
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