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Stratford Area Watershed Improvement Group: A Glimpse into the Exciting World of Watersheds on Prince Edward Island

Invasive Species Program

SAWIG is involved in invasive species management, identification and monitoring! Not only is our watershed coordinator a member of the PEI Invasive Species Council, but we have our own website where you can pin an area with invasive species! Not sure if what you’re looking at is invasive? Pin it anyway and we’ll check it out!  See below for some common species, or at the invasive species council’s website!

What is an invasive species?


Canada has a wide variety of species of plants and animals; the biodiversity of our country is amazing! Unfortunately, not all of these species are native to our area; in fact, there are some that should not live here at all!

To put it simply, an invasive species is “any species that is not native to an area and threatens the environmental, economic or social health of the area.”  (PEI Invasive Species Council, 2012).

How do invasive species get here?


Some of these plants and critters catch a ride from other parts of the country, or the world through various means; some mooch a lift on humans, in cargo, on the bottom of boats or in ship ballasts. Not all of these non-native species are a problem, but there are some that can pose serious risks to native flora and fauna.

What is the problem with invasive species?


Once a species is removed from its natural area (ecosystem), it may no longer have any predators or ways to keep the population in check. This means a particular species may be free to quickly reproduce, grow and take over entire areas once populated by native plants or animals. For this reason, invasive species often out-compete native species.

Purple Loosestrife (photo: Mike Ogden)

Purple Loosestrife (photo: Mike Ogden)

Who is Causing Damage Here?


     While all invasive species typically cause damage the PEISC has a prioritized list of the invasive species residents of Prince Edward Island should watch out for:

Yellow Flag Iris

Yellow Flag Iris is an ornamental planet which originates in Europe, Northwest Africa and Western Asia. It grows it moist ground and will be found in ditches, wetlands, and around waterways. You can identify Yellow Flag Iris by its sword shaped leaves which range from 0.5m- 1.5m long and 1-3cm in width with a raised ridge in the middle of the leaf.

Yellow Flag Iris

Yellow Flag Iris

  Containment

The PEISC recommends completely digging the plant from the ground. Care must be taken to remove all aspects of the plant, roots, rhizomes etc as the plant will grow again from the remainder. Mowing or cutting has been proven effective as it inhibits photosynthesis eventually killing the plant. In regards to both of these containment efforts the site must be monitored annually to ensure the plant has been eradicated.

Wild Cucumber

Wild Cucumber grows in most areas across PEI, alongside trails, in fields or in forest areas. Wild cucumber is a vine that grows on other shrubs and trees and can choke out smaller plants. It can easily by identified by its spiky fruit, and its leaves with have 5 lobes and a heart-shaped base.

Leaves of Wild Cucumber

Leaves of Wild Cucumber

Containment

Mowing or cutting the plant back in the spring is the best way of ensuring plant morality.

Scotch Broom

Scotch Broom grows in open habitats such as, fields, meadows or yards. It has an extensive root system so becoming very difficult to eradicate once established. Scotch Broom originated from Europe and was brought over originally as an ornamental plant. It has also been used as a coffee alternatives and used for medicinal purposes. Scotch Broom is identifiable by its yellow, pea-like flowers which bloom from May to June. The leaves near the base of the plant also contain 3 leaflets and it has a woody, angled stem.

Flower and leaves of Scotch Broom

Flower and leaves of Scotch Broom

Containment

Scotch Broom is difficult to manage as its seeds can remain viable in the soil for up to 30 years. Digging is only an option for small infestations. The best management strategy is to cut the plant to ground level and cover with thick black plastic.

Purple Loosestrife

Purple Loosestrife grows along waterways, choking out and destroying natural environments. It can be identified by its purple to pink flowers (5-7 petals) which grow on “spikes” which are 10-40cm long. Purple Loosestrife’s flowers bloom from July to September.

Purple Loosestrife

Purple Loosestrife

Containment

Digging is the most effective method of eradicating infestations of Purple Loosestrife. When digging, care should be taken to remove as much of the root system as possible to limit regrowth.

Periwinkle

Periwinkle can be found at ground level in forests and over shaded areas. It grows and spreads rapidly choking out most native ground cover plants. Periwinkle can be identified by its glossy, evergreen leaves and its pale blue flowers which are 3cm wide and have 5 petals. Periwinkle flowers bloom from May until June.

Periwinkle flowers

Periwinkle flowers

Japanese Knotweed

Japanese Knotweed was originally imported from Japan to North America as an ornamental garden plant. It is classified as one of the Global Invasive Species Database’s 100 worst invaders. It can be identified by its woody, bamboo like stem, the plant can grow 1-2m tall. Flowers are white-yellow and grow on small, branching, flowering stems which bloom between July and September.

Japanese Knotweed

Flowering Japanese Knotweed

Containment

The only effective method of eradication of Japanese Knotweed is cutting and covering. The plant should be cut to ground level and then completely covered in a non-degradable, opaque, dark plastic. The edges should be monitored for shoots and cut back.

Himalayan Balsam

Himalayan Balsam is commonly found in moist areas such as ditches and along streams. It’s particularly harmful as it has a short root system and when it dies back in the fall it leaves shorelines susceptible to erosion, It can be identified by its red, bamboo-like stem and sac-like deep pink to white flowers which bloom from June to October.

Himalayan Balsam

Himalayan Balsam

Containment

The most effective method of eradication is pulling. Himalayan Balsam’s weak root system makes it easily pulled from the ground. Cutting is also an effective method as long as the site is monitored for regrowth.

Glossy Buckthorn

Glossy Buckthorn tolerates a wide range of habitats from wetlands to woodland edges, old fields, ditches and grassy areas. Glossy Buckthorn is a large shrub with multiple stems with grey-brown spotted bark. Alternate leaves are shiny, oval-shaped with smooth edges. Leaves remain green late into the fall. The flowers are found in small hanging clusters and are white to whitish-green. The red berries turn purple or black when ripe.

Glossy Buckthorn

Glossy Buckthorn

Containment

Removing a two-inch wide ring at the base of the trunk is an effective method of eradication. This removes vascular tissue starving the plant of nutrients.

Common Buckthorn

Common Buckthorn grows in areas similar to its cousin, Glossy Buckthorn, and can be difficult to identify because of this. There are a few features that can be used to differentiate such as Common Buckthorn has slightly-toothed leaf edges while Glossy Buckthorn’s leaves have smooth edges and Common Buckthorn has a spike at the end of branches while the spike is absent in Glossy Buckthorn.

Common Buckthorn

Common Buckthorn

Containment

See Glossy Buckthorn.

Giant Hogweed

Giant Hogweed is generally found along roadsides, in ditches, along waterways and in disturbed waste areas. It can be easily identified by its massive height as they can grow up to 5m. Giant Hogweed’s umbrella-shaped flowers can also have a diameter of 1.5m.

Giant Hogweed

Giant Hogweed

Containment

Removal of the plants by digging or pulling is the most effective method of eradication. However, the plants sap causes severe photodermatitis. UV radiation from the sun activates compounds in the sap which can cause painful blistering of the skin. It is recommended to report all Giant Hogweed sightings to the PEISC and await their expertise.

Garlic Mustard

Garlic Mustard tolerates shade and grows in rich moist areas and can commonly be found invading forest floors. It is a cool season biennial herb with coarsely toothed triangular to heart-shaped leaves that give off a garlic or onion odour when crushed. Alternate leaves grow on stalks about 0.5-2 inches long. Mature flowering plants can reach up to 3.5 feet.

Flowering Garlic Mustard

Flowering Garlic Mustard

Containment

The most effective method of eradication is pulling of first year plants it is not effective to cut the plants until they have matured into their second year.

Bittersweet Nightshade

Bittersweet nightshade is a perennial, climbing vine. It grows in a wide range of habitats but prefers not to be in full sun. It can be found growing along hedgerows, forest edges, riparian zones and in forest understories. It can be identified by it’s heart-shaped leaves and emit an unpleasant scent when crushed.

Bittersweet Nightshade

Bittersweet Nightshade

What You Can Do


While removal of invasive species is a huge help in the fight against invaders, reporting all sighting to the PEI Invasive Species Council through their website, found here, is another important step.

If living in the Stratford Area you can also take advantage of the Stratford Area Watershed Improvement Group’s program, found here.

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