Manitoba
Purple Loosestrife Project's Top 10 FAQ
The following top 10 frequently asked questions were compiled from
numerous telephone calls received by Manitoba Purple Loosestrife
Project.
1.
What does Purple Loosestrife look like?
2.
Is my garden variety (cultivar) of Purple Loosestrife safe?
3.
How does Purple Loosestrife escape from my garden?
4.
What's so bad about Purple Loosestrife?
5.
I've had Lythrum in my garden for 25 years and it hasn't
spread to other locations in my yard or to my neighbor's yard.
Why should I get rid of it now?
6.
Are all Loosestrife varieties harmful to the environment?
7.
How can I get rid of my Purple Loosestrife?
8.
Which safe perennial are you exchanging for my Purple Loosestrife?
9.
How can insects help control Purple Loosestrife?
10.
Where did Purple Loosestrife Come From?
|
![Purple Loosestrife](images/camera1.jpg) |
Purple
Loosestrife. |
![Two metre high purple loosetrife.](images/camera2.jpg) |
Two
metre high Purple Loosestrife. |
![Fireweed and purple loosestrife](images/camera3.jpg) |
Don't
confuse Purple Loosestrife (right) with look alikes such as
fireweed (left). |
1.
What does Purple Loosestrife look like?
One of the most easily recognizable features of purple loosestrife,
at any time of the year, is its ridged, square stem. A single plant
can produce as many as 30 stems growing from a central, woody root
mass. The leaves are smooth, opposite, and attached directly to the
stem. Each plant can grow as tall as two meters. Loosestrife flowers
in late June to late September. The flowers are pink-purple in color
and are tightly clustered on a long spike. Don't confuse purple loosestrife
with look alikes such as fireweed with its round stem.
Back
to top.
2.
Is my garden variety (cultivar) of Purple Loosestrife safe?
No. Originally many garden varieties of purple loosestrife such as
Morden Pink, Morden Gleam or Dropmore Purple were considered to be
sterile (did not produce seed), safe horticultural cultivars. Recent
scientific studies have shown that these varieties are indeed capable
of pollen and seed production. These plants can readily cross pollinate
with other garden varieties, as well as wild loosestrife populations.
In a Manitoba study, Morden Pink cultivars were planted near a wetland
with purple loosestrife and six months later all Morden Pink plant
produced viable seed. The majority of wild infestations of purple
loosestrife are the result of garden escapes.
Back
to top.
3.
How does Purple Loosestrife escape from my garden?
Each purple loosestrife plant is capable of producing an enormous
number of seeds, up to three million every year. The seeds are small,
light and are easily dispersed by the wind, which carries them great
distances. In addition, loosestrife seeds have high viability, almost
100 per cent germination rate and remain viable after many years in
the soil or submerged under water. Purple loosestrife can also spread
vegetatively, by pieces of the stems or roots. Garden varieties of
loosestrife can also exchange pollen with other loosestrife cultivars
and wild populations. Flowers are commonly pollinated by bees, which
encourage pollen flow between gardens and wild populations. Garden
seeds can be transported by animals, on clothing or vehicles and rainfall
carries them into river systems and wetlands through storm water run-off.
Back
to top. |
![Monotypic stand of purple loosestrife](images/camera4.jpg) |
A
monotypic stand of Purple Loosestrife.
|
4.
What's so bad about Purple Loosestrife?
The nicknames for purple loosestrife - beautiful killer, marsh monster
and exotic invader - are telling. An invasive, weedy species, loosestrife
readily establishes in a variety of urban and rural wetland habitats.
Once it's present, it has a tendency to dominate, outcompeting native
vegetation. The result is solid (monotypic) stands of purple loosestrife.
This drastic change in species composition and decrease in biodiversity
affects everything from the nutrient cycling regime to wildlife
usage. The displacement of native vegetation by purple loosestrife
has many far reaching ecological implications, many of which still
remain unknown. In urban areas loosestrife commonly takes hold in
ditches and can block or disrupt water flow. In agricultural regions
it can clog irrigation canals and reduces the value of forage. Once
established, it is extremely difficult to eradicate. No herbicides
are currently approved to control loosestrife growing in or near
waterways. Small outbreaks can be removed by hand digging, but for
large scale infestations this is too costly and time consuming.
Since purple loosestrife can regenerate from even the smallest piece
of root tissue left in the soil, digging is not a viable long term
solution.
Back
to top.
5.
I've had Lythrum in my garden for 25 years and it hasn't spread
to other locations in my yard or to my neighbor's yard. Why should
I get rid of it now?
For many years garden loosestrife cultivars were considered to be
sterile and safe for garden use. Studies have now shown this to be
false. Unfortunately, purple loosestrife has become popular among
horticulturalists, who enjoy the beauty of this hardy perennial. Conflict
has arisen between environmentalists and the horticultural community
as a result. Many gardeners still believe that their loosestrife is
sterile, especially since the damage that it causes may not be noticeable
in the immediate vicinity of the home. There are several benefits
to removing garden varieties of loosestrife. First, a potential source
of pollen exchange is removed from the environment which can decrease
the number of plants that become fertilized and set seed, preventing
existing plants from spreading to new areas. Most loosestrife infestations
originate from garden cultivars. Removing all loosestrife plants can
prevent future outbreaks, as well as reducing the potential for cross-fertilization.
In addition, purple loosestrife is considered a noxious weed in several
provinces and states, including Manitoba. Therefore, it is illegal
to sell or possess any Lythrum cultivar. If a complaint is
registered regarding loosestrife on your property, the plants can
be removed at the owner's expense by local weed control authorities.
Back
to top.
6.
Are all loosestrife varieties harmful to the environment?
All varieties of purple loosestrife are harmful to the environment.
This includes wild loosestrife (Lythrum salicaria) and garden
cultivars such as Morden Pink, Morden Gleam and Dropmore Purple. Fringed
loosestrife and tufted loosestrife are from a different family known
by the scientific name Lysimachia and are both noninvasive,
native species.
Back
to top.
7.
How can I get rid of my Purple Loosestrife?
The best way to remove purple loosestrife from your yard is by hand
digging. Make sure that all pieces of root tissue are removed and
dry out the plant material thoroughly before disposal. Root masses
can be treated with a herbicide, such as Round-Up. Place all purple
loosestrife plant material in a dark colored garbage bag and ensure
that the bag is tightly secured to prevent it from spreading in the
landfill area. Wherever permitted, plant material should be burned.
For large scale infestations and when digging is not feasible, removing
the flower head is an easy alternative. Cut off the top of the plant
in midsummer before the flowers set seed. Monitor the dig site for
a couple of seasons to ensure no new plants are growing and, if so,
remove promptly.
Back
to top.
8.
Which safe perennial are you exchanging for my Purple Loosestrife?
The plant chosen for the exchange program is Spiked Gayfeather (Liatrus)
also called Blazing Star. A native plant with pink, purple or white
flowers, it is an environmentally safe perennial. It requires full
sunlight to partial shade and can grow up to five feet, blooming from
midsummer to early fall.
Back
to top. |
![Galerucella leaf beetles.](images/camera5.jpg) |
Galerucella
leaf beetles. |
![Hylobius transversovittatus weevil.](images/camera6.jpg) |
Hylobius
transversovittatus weevil. |
![Nanophyes marmoratus weevil](images/camera7.jpg) |
Nanophyes
marmoratus weevil |
![Marsh in 1994 before introduction of beetles.](images/camera8.jpg) |
Marsh
in 1994 before introduction of beetles. |
![Same marsh in 1998 showing effects of beetles on Purple Loosestrife.](images/camera85.jpg) |
Same
marsh in 1998 showing effects of beetles on Purple Loosestrife. |
![Infestation in Netley-Libau Marsh, Manitoba, 1999.](images/camera9.jpg) |
Infestation
in Netley-Libau Marsh, Manitoba, 1999. |
9.
How can insects help control Purple Loosestrife?
When purple loosestrife was introduced into Canada, it escaped its
natural enemies that control its spread in its European range. Biological
control reunites a target weed such as purple loosestrife with its
natural enemies. There are four insects approved for release against
Purple Loosestrife in Canada - two leaf eating beetles called Galerucella
calmariensis and Galerucella pusilla, a root mining weevil
Hylobius transversovittatus and the seed weevil Nanophyes
marmoratus. These specialized plant eating insects do not eat
any other plants or harm our natural environment. In many areas of
North America, beetles are providing almost total control of purple
loosestrife. Prior to biological control there was no effective method
of controlling purple loosestrife. This also means that herbicides
and chemicals do not have to be used in sensitive areas like wetlands.
Back
to top.
10.
Where did Purple Loosestrife Come From?
Purple loosestrife is an invasive perennial weed that was introduced
into North America in the early 1800s. It is believed that it was
introduced as a contaminant in European ship ballast and as a medicinal
herb for treating diarrhea, dysentery, bleeding and ulcers. By the
'30s, purple loosestrife was well established along the east coast
and spread inland with the construction of waterways, drainage systems,
canals, railways and highways. The first published report of purple
loosestrife in Manitoba came from the Neepawa area in 1896. The next
reported collection of purple loosestrife was near Lockport in 1944
and then in Winnipeg seven years later. Purple loosestrife can now
be found in all major watersheds in southern Manitoba with large infestations
in the Netley-Libau Marsh.
Back
to top.
The Manitoba Purple Loosestrife
Project gratefully acknowledges funding received through Environment
Canada's EcoAction 2000 fund, Ducks Unlimited, the City of Winnipeg,
Urban Green Team, Murphy Foundation, Manitoba Hydro, Sustainable Development
Innovations Fund and Manitoba Conservation.
Special thanks to Colleen
Simpson and Remi Verfaillie.
|
|