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Invasive Phragmites near a waters edge

Invasive Species

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Invasive Plant Species in Muskoka

The District has identified three key invasive plant species that are having a serious effect on Muskoka's environment. These include Invasive Phragmites (Phragmites australis subsp. australis), Japanese Knotweed (Fallopia japonica) and Giant Hogweed (Heracleum mantegazzianum).  

Plants species, like the ones listed above, become a concern when they are introduced, either accidentally or purposefully, to an area they aren’t naturally found in. Because they typically are able to reproduce rapidly, thrive in disturbed areas, are highly adaptable and have few natural predators, they are able to out-compete native species for habitat and resources and thus become invasive. Their introduction and spread to an area like Muskoka threatens local ecosystems, the economy and, in the case of Giant Hogweed, our health.

Invasive species are extremely difficult to eradicate once established and their ecological effects are often irreversible as they can alter entire habitats and/or food webs, decrease biodiversity, and threaten species at risk.

Our overall goal is to stop the spread of invasive species and eradicate existing problem species before they become well established in Muskoka.  

Learn more about these invasive species below.

Invasive Phragmites Australis beside a waterbody
Invasive Phragmites

(Phragmites australis subsp. australis)

Identifying Invasive Phragmites
One factor making the identification of invasive Phragmites difficult is the existence of a closely related native subspecies. A number of characteristics of the plant can be useful in distinguishing between the native variety and invasive Phragmites. 

Invasive Phragmites:

  • grows in stands that can be extremely dense with as many as 200 stems per square metre;
  • can grow so densely that it crowds out other species;
  • can reach heights of up to 5 metres (15 feet), and
  • has stems that are tan or beige in colour with blue-green leaves and large, dense seedheads.

Native Phragmites:

  • grows in stands that are usually not as dense as the invasive plant;
  • well-established stands are frequently mixed with other plants; and
  • usually has more reddish-brown stems, yellow-green leaves and smaller, sparser seedheads.
 
Impacts of Invasive Phragmites
  • Invasive Phragmites uptake nutrients from their environment and out-compete native plants such as cattails and willows; they result in loss of habitat for other plants and animal/aquatic life and further jeopardize species at risk
  • Inhibit agricultural drainage ditches and cause flooding
  • Can have a density of 200 plants per square metre; their dead stalks resist decay, filling in open ponds and creating dead zones unusable for wildlife
  • Once their seeds colonize an area, they spread quickly with seeds and rhizomes (horizontal plant stems growing underground).
  • Further spreading by earth moving equipment along roadways, in new subdivisions, and across farm fields
    (do not put in a garbage bag or attempt at having these plants collected at the curb)
 
What Can You Do?
  • Learn how to identify invasive Phragmites and how to avoid accidentally spreading it through its root fragments and seeds. This is especially important if you are planning to do work on your property which contains invasive Phragmites.
  • Do not plant invasive Phragmites. Native Phragmites have the same appearance and do not pose an ecological risk.
  • Gardeners should use only native or non-invasive plants and are encouraged to ask garden centres for plants that are not invasive.
  • Stay on designated trails. Leaving trails or entering areas containing invasive Phragmites can encourage the spread of this plant. When leaving an area containing invasive Phragmites, brush off clothing and clean equipment onsite to avoid the transfer of seeds to new areas. 
  • Do not compost invasive Phragmites. Both seeds and rhizomes (horizontal plant stems growing underground) can survive and grow in backyard composters.
 
Managing Invasive Phragmites on Private Property
Invasive Plant Species cannot be collected at the curb, due to the possibility of seed spread during transportation. 

Any mature invasive plants with seeds should be carefully bagged in a sealed household sized garbage bag and loaded into your vehicle (covered with a tarp or canopy), and disposed of at the Rosewarne Landfill in Bracebridge. We cannot accept these materials at Transfer Stations, as the seeds could become airborne and spread throughout our area. They must be delivered to their final destination at Muskoka's operating Landfill (Bracebridge). 

Be sure to inform the Guard upon entering that you have invasive plants (and not simply yard waste), to ensure that your Invasive Weeds are disposed of in the proper location. 
Report a Sighting 
If you find invasive phragmites or other invasive species in the wild, please contact the Invading Species Hotline at 1-800-563-7711, or report a sighting online. 
Helpful Resources and Downloads

Download the Invasive Phragmites ID Card from Muskoka Watershed

Phragmites Fact Sheet (300.6 Kb)

Grow Me Instead (11.9Mb)
Ontario's Invading Species Awareness Program Website 

Japanese Knotweed
Japanese Knotweed

(Fallopia japonica) 

Identifying Japanese Knotweed 
The stalks grow straight up and can reach as high as 3 metres. The stems appear to be round and reddish-purple in colour. Large, heart-shaped leaves form in a zigzag pattern along the hollow stem. Flowers are cream-coloured that grow vertically from the stem in clusters. 
Impacts of Japanese Knotweed
Japanese knotweed has a strong root system and can spread about 10 metres from the parent stem and has the ability to grow through concrete and asphalt. This fast growing invasive species is known to change river flows, interrupting spawning beds, it rips through roadways and even threatens foundations of homes.

Knotweed commonly grows in gardens, along roadsides and near old buildings or former building sites, according to Ontario's Invading Species Awareness Program.Some studies suggest the plant has extended its range by climate change. While knotweed stems are known to survive temperatures as low as -35C, Canadian frigid winters could be the country's saving grace as the cold will slow down the growth.

 
Managing Japanese Knotweed on Private Property 

Unfortunately, getting rid of this plant is very difficult. While digging and cutting knotweed is a solution, this method can break up the rhizomes, creating more growing ends.

To control the spread of Japanese knotweed in gardens and residential properties, stems must be cut down several times throughout the growing season to deplete the root system.  Cut the base of the stalk just before flowering once the plant reaches a height of 5 to 6 feet. This usually occurs around mid to late June in Muskoka. Subsequent cuttings may occur around early August and again in early September. Persistent cutting may be combined with other options such as digging out roots and laying down tarp material for several years in order to successfully control this species.  

 

Invasive Plant Species cannot be collected at the curb, due to the possibility of seed spread during transportation. 
Any mature invasive plants with seeds should be carefully bagged in a sealed household sized garbage bag and loaded into your vehicle (covered with a tarp or canopy), and disposed of at the Rosewarne Landfill in Bracebridge. We cannot accept these materials at Transfer Stations, as the seeds could become airborne and spread throughout our area. They must be delivered to their final destination at Muskoka's operating Landfill. 

Be sure to inform the Guard upon entering that you have invasive plants (and not simply yard waste), to ensure that your Invasive Weeds are disposed of in the proper location. 

Report a Sighting 
If you find invasive Japanese Knotweed or other invasive species in the wild, please contact the Invading Species Hotline at 1-800-563-7711, or report a sighting online. 
Helpful Resources
Grow Me Instead (11.9Mb)
Japanese Knotweed Fact Sheet (2Mb)
Ontario's Invading Species Awareness Program Website 
Giant Hogweed
Giant Hogweed

(Heracleum mantegazzianum)

What is Giant Hogweed?
Giant Hogweed, (Heracleum Mantegazzianum), is an invasive plant known for its enormous size. Giant Hogweed has two major negative impacts. Firstly, due to its invasive nature, it poses a threat to native biodiversity. Secondly, Giant Hogweed is a public health hazard. It produces a noxious sap that sensitizes the skin to ultraviolet light. This is known as photosensitivity, which can result in severe and painful burning and blistering. It is important to avoid any skin contact with this plant.
  • The plant can grow from 2.5 to 4 metres high (8 - 14 feet).
  • The saw-toothed leaves are deeply lobed and can grow to 1 metre (3 feet) across.
  • The stems are hollow with dark reddish-purple splotches and coarse white hair.
  • The watery sap produced by the leaves and stems contains a chemical that causes skin to become highly sensitive to the sun.
  • Small white flowers are clustered in an umbrella-shaped head that can grow larger than 30 centimetres (1 foot) in diameter.
  • The seeds are oval and flat.
Where is Giant Hogweed Found?
It can be found along:
  • roadsides
  • vacant lots
  • stream banks
Is Giant Hogweed a Risk to Human Health?

Yes.

  • Contact with the sap of Giant Hogweed can cause photodermatitis, a serious skin inflammation.
  • Temporary or permanent blindness can occur if sap enters the eye.
  • The sap contains chemicals called furanocoumarins that get absorbed by the skin and cause the affected area to become highly sensitive to ultraviolet light from the sun.
  • The exposed skin can turn red and blister, sometimes leaving scars and discolouration.
  • The severity of the skin reaction will depend on the sensitivity of the person. Heat and moisture (sweat) can enhance the reaction.
  • Reactions can occur up to 48 hours after contact.
Are There Other Plants That Look Like Giant Hogweed? 

Yes.
Muskoka is home to is a number of native plants that resemble Giant Hogweed but do not pose the same health risks. When in doubt, always confirm plant identification with an expert. 

  • Its "giant" size helps to distinguish giant hogweed from other plant species.
  • Cow Parsnip, Purple-Stemmed Angelica, Spotted Waterhemlock, Poison Hemlock and Wild Parsnip (a relative to Giant Hogweed that is also dangerous)  are often mistaken as Giant Hogweed. 
 
Managing Giant Hogweed on Private Property
  •  DO NOT TOUCH! Keep children and pets away from the area.
  • Resources are provided below to help you to identify giant hogweed.
  • For safety reasons, property owners are encouraged to contact a licensed weed exterminator to remove Giant Hogweed from private property. Licensed weed exterminators can be found under "Weed Control Services" in the Yellow Pages or by searching online for local weed control experts.
  • DO NOT compost giant hogweed or place it out for curbside collection as garbage, yard waste or in the Green Bin. Licensed weed exterminator's are experienced in disposing of this invasive, dangerous weed.
  • Following removal or treatment, monitor the area for plant regrowth.
Report a Sighting
If you find invasive Giant Hogweed or other invasive species in the wild, please contact the Invading Species Hotline at 1-800-563-7711, or report a sighting online.
Helpful Resources

Giant Hogweed Fact Sheet (1Mb)

Ontario's Invading Species Awareness Program Website 

 

You can help prevent the spread of unwanted invasive plant species by identifying and reporting sightings in Muskoka by visiting https://www.eddmaps.org/ontario/.

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Bracebridge, ON P1L 1N3

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