Invasive Species: Oakville’s Most Wanted

Invasive Species: Oakville’s Most Wanted

Some invasive species in Oakville are more problematic and damaging than others. See below for a list of Oakville’s top offenders, how to ID them, native plant look-alikes, and how to remove each species.

Norway Maple (Acer plantanoides)

Norway Maple is a species of maple introduced from Europe and Western Asia. In North America, the tree has become prized for its full crown and its hardiness in challenging urban environments. Norway Maple was planted extensively as a municipal street tree until recently. There are many cultivars, including the burgundy-leaved ‘Crimson King’ and variegated versions, which continue to be sold widely in nurseries. Norway Maple trees are problematic because they spread rapidly into woodland ecosystems, out-competing native trees and displacing understory vegetation. Norway Maples release toxins into the surrounding soil that affects the soil chemistry and discourages plant growth. The tree also produces abundant seeds that spread widely, with fast rates of germination, and seedlings that grow very quickly even in dense shade.

Identifying the Norway Maple

Leaves: Maple-shaped leaves can be varying shades of dark green to red (depending on the variety). The shape of the leaves is very similar to the native sugar maple (Acer saccharum), however, when picked and pinched, Norway Maple leaves produce a milky sap that is not found in sugar maples. The buds are purple and oval.

Image Credit: Credit Valley Conservation 

Seeds: Norway Maples seeds are paired keys in the shape of an upside down “ T ”. They are in an open shape with the two seeds being set close to a 180-degree angle from each other.

Image Credit: Credit Valley Conservation 

Bark: Dark and set into tight diamond patterns along the trunk.

Image credit: The Tree Pages 

Norway Maple Look-Alikes

Sugar Maple: Unlike the Sugar Maple and other native Maple trees, the Norway Maple will drop its leaves earlier in the fall. In addition, when pinched, the sap from the leaves of a Sugar Maple will be clear and watery, whereas the sap from a Norway Maple leaf will be white and milky. Another core difference is that Sugar Maple keys will appear closed and will be pointing down in a “ V “ or “ U” shape. When looking at the bark of the Sugar Maple the bark will be in long slightly peeling strips.

 

Image Credit: The Government of Ontario and Daniel Tigner, Canadian Forest Tree Essences

Norway Maple Removal and Management

As municipalities have planted Norway Maples, it is important to ensure you know if the tree in question is a private or municipal tree. It is also necessary to be aware of and follow any local by-laws regarding tree removals and landscaping. Should the by-laws allow the trees to be removed and you wish to address the Norway maple(s) on your property, the following advice from the City of Toronto may be useful.

  • Seedlings may be dug out of the ground and properly disposed of according to your municipality.
  • Small seedlings may be cut at the base of the stem.
  • Small and medium-sized trunks can be griddled to kill the tree, however, there are other options available for trees of this size.
  • Medium and large trees should be looked at by an arborist or other specialists to ensure that the tree is removed safely and legally.

Sources:

https://www1.toronto.ca/wps/portal/contentonly?vgnextoid=05a730d2da32c410VgnVCM10000071d60f89RCRD&vgnextchannel=17f4cacb759e0410VgnVCM10000071d60f89RCRD

Source: http://reforestlondon.ca/identifying-common-invasive-trees-london

Plants of Southern Ontario, Richard Dickinson, 2014.


European Buckthorn (Rhamnus cathartica)

The European Buckthorn was brought to North America in the 1800’s as an ornamental plant that was primarily used for hedging. European Buckthorn alters the nitrogen composition of the soil which allows it to more easily out-compete native plants. Unlike native berries, the fruit of the European Buckthorn provides few nutrients and calories for birds, and may act as a laxative for the animals that eat it. European Buckthorn is typically the first shrub to leaf in the spring and the last to drop its leaves in the fall, giving it a longer growing season than most native plants.

Identifying European Buckthorn

Leaves: The smooth dark green leaves of the European Buckthorn are finely toothed and can be between 2.5 to 5 centimetres long. The leaves are opposite on the branch. A useful identifying feature of European Buckthorn is the veins on the leaves. The leaf veins will extend towards the tip of the leaf rather than out to the sides. In addition, if the leaf is picked and torn it will not have any visible fibres, unlike common look-alike species.

Image Credit: Ontario Trees and Walter Muma

Seeds: In late summer and in the fall the European Buckthorn will produce dense clusters of fruit. These fruits are berry-like in their appearance and start off green, but turn to a dark purple-black colour when ripe.

Image Credit: Ontario Trees and Walter Muma

Flowers: Flowers on the European Buckthorn have 2 to 6 small petals that range from yellow to green.

Image Credit: Ontario Trees and Walter Muma

Height and Diameter: Two to three meters tall, though it can reach upwards of six meters. Trunk diameter can reach up to 25 centimetres. Often has multiple stems at the base.

Image Credit: Ontario Trees and Walter Muma

Additional features: Branches of the European Buckthorn that are older than one year will end in a small sharp thorn.

Image Credit: Ontario Trees and Walter Muma

European Buckthorn Look-Alikes

Alderleaf Buckthorn: Unlike its invasive cousin, the Alderleaf Buckthorn is a native species in Canada. One distinguishing characteristic of the Alderleaf is that the veins on the leaf go straight out to the side rather than curving to the tip like the European Buckthorn. The flowers of the Alderleaf Buckthorn are about 3 millimetres wide with five petals. Both the European and Alderleaf Buckthorns have berry-like fruit in clusters of one to three berries. Regardless of the age of the branches, there will be no thorn on the end of the Alderleaf Buckthorn branches. The native Buckthorn is also notably smaller as they do not grow to more than a meter in height.

Image Credit: Ontario Trees and Walter Muma

European Buckthorn Management and Removal

One of the challenges with managing European Buckthorn plants are their ‘hydra-like’ tendencies. If Buckthorn stems are cut down at the base, or the entire root system is not removed or treated, the plant will re-grow a number of new shoots at the bottom of the plant. It is because of this regrowth that the entire plant needs to be removed to ensure it does not grow back. Below are suggestions on how to address European Buckthorn on your property.

  • Small plants can be removed by hand pulling but be sure to get the full root system out.
  • Plants that are bigger than a seedling will need to be dug out with a shovel or removed with a lever tool. We use the extractigatorTM.
  • Should the removal of the full root system not be possible, placing a tarp over cut stems or nailing an inverted empty metal can over the cut stem at ground-level for several growing seasons may be beneficial.
  • Unripened berries can also be cut off and properly disposed of to help control the spread of European Buckthorn. Berry removal would need to be done yearly.
  • It is advisable to mulch areas where mature plants have been removed as this can make it more challenging for any seeds in the seed bank to sprout. Mulching should be repeated over multiple growing seasons. Alternatively, native species can also be replanted where the Buckthorn has been removed.

Sources:

http://www.oakville.ca/residents/invasivespecies.html,

http://www.invadingspecies.com/invaders/plants-terrestrial/common-buckthorn/

http://www.restoringthelandscape.com/2010/10/invasive-buckthorn-and-native-look.html


Common Reed (Phragmites australis subsp. australis)

Common Reed (Phragmites australis subsp. australis) is another particularly problematic invasive species in Halton. In 2005, Agriculture and Agrifood Canada identified Phragmites as the worst invasive species of plant in Canada. One of the challenges of this species is that it forms dense systems of roots and rhizomes which release toxins and outcompete native species for water and nutrients.

Identifying Invasive Phragmites

Leaves: Phragmites leaves are a blue-green colour and stick out at a 45-degree angle from the stem. The internodes where the leaf connects to the stalk can be red. The leaf sheaths of the invasive Phragmites are difficult to remove, which can serve as a key identifying feature.

Image Credit: Tip of the Mitt Watershed Council

Stalks: The stalk of the plant is a tan, beige, or green.

Image Credit: Nature of New York   Image Credit: Wood Bay Phrag Fighters

Seeds: The seed heads are large, beige and grow in dense clusters.

Image Credit: Chesapeake Bay Program 

Height: Phragmites can reach heights over six meters tall.

Density: Phragmites grows in thick stands that can reach densities up to 200 stems per square meter. This density can crowd out other species, which can lead to a monoculture.

Invasive Phragmites Look-Alikes

Native Phragmites: The native Phragmites (Phragmites australis subsp. americanus) grows significantly smaller than its invasive cousin. In the eastern US and Canada, the native subspecies has been largely replaced by the non-native subspecies. Native Phragmites would grow more sparsely and is less likely to be dense monoculture. The stems are more flexible than invasive Phragmites and are red under the leaf sheath. The parts of the stem that are not covered will be green. Leaves on the native Phragmites will also come off easily and will stick out at a 30-degree angle. Native Phragmites seeds will have fairly sparse heads with small seeds. Lastly, the stem of the native Phragmites is flexible, unlike the invasive counterpart.

Image Credit: Tip of the Mitt Watershed Council

Invasive Phragmites Management and Removal

Since invasive Phragmites has a rather extensive rhizome system under the soil, it will likely require multiple methods of control. As a result, the OIPC recommends using Integrated Pest Management practices, though the specific approaches necessary will vary based on the plant size, stage, location, the time of year and more. Once Phragmites has been introduced to a water way it is very difficult to remove, making it important to take preventative measures.

  • Chemical methods can be used, however, due to the ecological and health risks along with provincial and municipal laws, they should only be used by professionals.
  • If the plant is less than 2 years old and is in sandy or dry soil it can be pulled out by hand.
  • Older plants can be removed with a straight edged shovel by cutting out as much of the stem below the surface of the soil.
  • When the plant is removed it is important to ensure that all of the rhizomes are taken out.
  • After the tops of the plants are cut or removed, tarping can be used to cook the roots. When this is done any plant materials should be removed before the tarp is placed. The tent should then be left for a minimum of six months. The edges of the tarp should be regularly monitored to ensure that new plants to not growing up at the edges of the tarp.
  • If the plants are in water, tenting can be used in place of tarping.
  • Any plants or plant materials that have been removed should be placed in dark garbage bags and left to ‘cook’ the sun for 1-3 weeks to ensure all the material has been killed.

Sources:

http://www.invadingspecies.com/invaders/plants-terrestrial/invasive-phragmites/

http://www.ontarioinvasiveplants.ca/wp-content/uploads/2016/07/2016-Phragmites-Webinar_-Feb-3-2016_ALWL.pdf 


Garlic Mustard (Alliaria petiolata

Garlic Mustard was first found in North America in 1868. It was introduced as a herb, a medical plant, and to help deal with erosion. However, as a plant that creates very dense monocultures due to the biochemicals it releases into the soil, it proved itself to be a problematic invasive species that displaces native species. Garlic mustard’s primary method for spreading its seeds is through humans, pets, and wildlife making it important to wash the dirt off your shoes, bikes and pets when leaving a location. With each plant being able to produce up to 8000 seeds in a season, it’s no wonder that Garlic Mustard is able to double its population every four years.

How to Identify Garlic Mustard

Leaves: When crushed, the leaves will release a strong garlic smell. They will have sharp teeth and are triangular in shape. The leaves at the base of the plant are in a broad kidney or heart shape. Garlic Mustard leaves can be up to 10 centimetres wide. During the first year of the plant’s life, they are small clusters of rosette shaped leaves.

Height: While the height of the stem will vary based on the age of the plant, adult Garlic Mustard will typically be .3 to 1.2 meters.

Flowers: In May the plant will grow white flowers that each have four petals.

Seeds: The seedpods are narrow and approx. 2.5 to 6cm long. Garlic Mustard seed pods will open in around the middle of the summer to show their small black seeds.

Year One:

  • There are three to four leaves per rosette that are two to twelve centimetres in diameter.
  • The leaves at this point will be a dark green and are shaped like a heart.
  • Some leaves may appear wrinkled due to their deep veins and scalloped margins.
  • A key ID feature is the slim and white ‘ S ‘ shaped taproot.
  • There are no flowers during this stage of the plant’s life.

Image Credit: Yamhill Soil and Water Conservation

Older Plants:

  • The older plants can reach upward of 1 metre.
  • The stem of the plant will have small hairs.
  • Leaves are alternate and are coarsely toothed.
  • At this point in the plant’s life cycle, it will produce small white flowers in early May.
  • After flowering the Garlic Mustard will set seed. Each seed pod will contain 10-20 black seeds.

Garlic Mustard Look-Alikes

Garlic mustard can be confused with Thaspium and Zizia species, both of which are members of the carrot families. Garlic mustard leaves can also be confused with a number of plants in the daisy and violet families.

While there are visual differences between Garlic Mustard and native look-alikes, the easiest way to determine if the plant in question is Garlic Mustard is to crush the leaves. If they give off a strong garlic smell, it is most likely a Garlic Mustard plant.

Garlic Mustard Management and Removal

  • Due to the narrow taproots of the plant, hand pulling is the easiest method to get rid of isolated and new patches of Garlic Mustard.
  • While it is possible to mow or cut the plants when dealing with larger patches, pulling will lead to more effective results in the long run.
  • Regardless of which method of control is chosen, it is important to get the plant at the rosette stage or before it goes to seed around mid-summer.
  • It is important to focus, first, on new invasions as they appear to prevent spreading.
  • When the plants are removed it is important to place all plant material into a dark garbage bag and let it ‘cook’ in the sun for 1-3 weeks. The plant material should NOT be composted.
  • After the plants have been removed, the area should be covered in mulch or soil to discourage regrowth or the growth of other invasive plants. Alternatively, native species can be replanted where the Garlic Mustard has been removed.

Sources:

http://www.invadingspecies.com/invaders/plants-terrestrial/garlic-mustard/

http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Alliaria_petiolata.html 


Dog-strangling vine (Vincetoxicum rossicum)

The dog-strangling vine is native to Eastern Europe. It is unclear if the dog-strangling vine was brought to Ontario for horticultural use or if it was an accidental introduction. Despite being a member of the Milkweed (Asclepiadaceae) family, the dog-strangling vine is not a host plant for monarch butterfly caterpillars. Monarch butterflies may mistakingly lay eggs on the dog-strangling vine and when the eggs hatch into caterpillars, they are unable to eat the plant causing them to starve. The plant’s long twining vine growth form and the formation of dense monocultures, as well as allelopathic chemicals released from the dog-strangling vine’s roots make the plant detrimental to the growth of native species and alter native ecosystems structure and function.

Identifying Dog-Strangling Vine

Height: Dog-strangling vine can grow between one to two meters tall by twining itself onto other plants and structures.

Image Credit: Friends of Raymore Park

Stems: The stems will twine and grip onto nearby plants and structures to support itself.

Image Credit: The City of Toronto 

Leaves: The leaves are oval, dark to light green and narrow to a pointed tip. The dog-strangling vine’s leaves grow between seven to twelve centimetres and are on opposite sides of the stem. The leaves will be smaller at the base of the plant reaching closer to five to seven centimetres wide.

Image Credit: Matilda Magtree 

Seeds: The Dog-strangling vine has seedpods in the shape of beans. They will vary from four to seven centimetres long and seeds are attached to white fluff that resembles seeds of the milkweed plant. The pods will be produced in late July and August.

Flowers: The flowers range in colour from a red-brown to maroon and appear in late June and July. Resembling a star, these small flowers have five petals and are five to nine millimetres wide. The dog-strangling vine’s flowers will grow in clusters of five to twenty flowers.

Image Credit: Credit Valley Conservation 

Density: Due to their tendency to form monocultures, the vines can often be found in thick groupings.

Dog-Strangling Vine Look-Alikes

Milkweed: Young dog-strangling vine seedlings may be confused with some native milkweed species.  Swamp milkweed (Asclepias incarnata) looks the most similar to the seedling stage of a dog-strangling vine. However, swamp milkweed and all other native milkweeds grow upright and they do not twist or twine like dog-strangling vine. Native milkweed flowers and seedpods are also distinct.

Butterfly Milkweed

Image Credit: Lary Stritch and the United States Department of Agriculture Forest Service

Common Milkweed

Image Credit: Randy Tindall and Nadia’s Backyard 

Swamp Milkweed

Image Credit: Edith Smith and Butterfly Fun Facts 

Sunflower: The seedlings of members of the Sunflower family (Helianthus) may resemble the dog-strangling vine. Unlike the dog-strangling vine, wild sunflowers grow straight and will not twine. In addition, sunflowers will have soft, fine hairs on the stem or a distinct leaves with three ridges extending from from the base of the leaf.

Image Credit: Tall Grass Ontario 

Dogbane: When trying to decide if a plant is dogbane (Apocynum sp.) or dog-strangling vine they are three key features to look out for. First, the leaves of dogbane are typically longer and narrower. Secondly, as dogbane matures the stems will become a more purple to red colour. Finally, the stems are always straight and do not twine.

Image Credit: Cathie Bird and Gardening Know How

Other native vines: Unlike the dog-strangling vine, other native vines, such as wild grape, will not twine as they grow. Instead, they will use tendrils to grip onto other plants and structures.

Dog-Strangling Vine Management and Removal

  • A combination of mechanical control methods and chemical control may be needed to eradicate dog-strangling vine from a specific location. Consult the OIPC Best Management Practices document below to determine how to develop an effective control plan.
  • Digging can be a good way to remove dog-strangling vine but it is important to ensure that the root crown is removed and any removed plant material is bagged and ‘cooked’ properly.
  • When dog-strangling vine infestations are larger, a combination of control methods may be useful: remove ripening seed pods, cut or mow the plants, and/or tarp the space they are in.
  • Whatever method is chosen, it is important to put any plant material into black plastic bags and seal the bags tightly and allow them to ‘cook’ in direct sunlight for 1-3 weeks before being disposed of in a landfill.
  • Once the area has been cleared, it should be mulched or replanted with native species to ensure that invasive species do not take root in the disturbed soil.

Source:

http://www.invadingspecies.com/invaders/plants-terrestrial/dog-strangling-vine/

http://www.ontarioinvasiveplants.ca/wp-content/uploads/2016/06/OIPC_BMP_DogStranglingVine.pdf


Honeysuckle (Lonicera spp.)

The invasive Honeysuckle was introduced to North America in 1800’s for their flowers and as an ornamental plant. Native to China, Japan, and Korea, invasive Honeysuckle plants release a chemical into the soil that is detrimental to nearby native plants and out-competes the native species for nutrients and space. The berries of the invasive Honeysuckles do not provide the name nutritional value to birds and songbirds, which in turn has a negative impact on them when more nutritious native species are displaced. In Ontario, the three most common invasive Honeysuckle species are: Amur Honeysuckle (Lonicera maackii), Tatarin Honeysuckle (Lonicera tatarica) and Morrow Honeysuckle (Lonicera morrowii).

Identifying Invasive Honeysuckles

One notable feature of invasive Honeysuckle species is that they will leaf out earlier and will keep their leaves later than most native species.

Identifying Amur Honeysuckle

Leaves: The leaves will be opposite and in an oval shape that narrows to a tip. They can be up to 3.5 inches long and have a soft hairy feel.

Image Credit: Missouri Botanical Garden 

Flowers: Amur Honeysuckle flowers are white and will fade to yellow. They appear in pairs, are tubular in shape, and are 2-4 millimetres. These flowers have 5 petals, though the top 4 are fused together.

Image Credit: Missouri Botanical Garden 

Stems: Like the other invasive Honeysuckle this is a multi-stemmed plant. The Amur Honeysuckle will also have hollow stems between the leaf nodes. The bark is white or tan and the pith will be brown.

Image Credit: Missouri Botanical Garden 

Fruit: The fruit of the Amur Honeysuckle are red to orange berries that can be seen starting late in the summer and will last into the winter.

Image Credit: Missouri Botanical Garden 

Height: This shrub will reach up to six meters in height.

Additional Information: The Amur Honeysuckle, like other Honeysuckles, are deciduous.

Identifying Morrow Honeysuckle

Leaves: The leaves on the Morrow Honeysuckle are also opposite on the stem and have an oblong shape that ends in a tip.

Image Credit: Missouri Botanical Garden 

Flowers: Like the Amur Honeysuckle, the Morrow Honeysuckle flower is white though it can also range to pink. The stalks that the flowers will feel hairy to the touch.

Image Credit: Will Cook and Carolina Nature 

Stems: The Morrow Honeysuckle is a multi-stemmed deciduous shrub. The twigs will appear hairy and will have brown pith.

Image Credit:  Carolina Nature 

Fruit: Similar to the other invasive Honeysuckles the fruit is a red berry.

Image Credit: Will Cook and Carolina Nature 

Height: This shrub will reach up to two and a half meters in height.

Image Credit: Missouri Botanical Garden 

Identifying Tatarian Honeysuckle:

Leaves: The leaves of the Tatarian Honeysuckle are opposite and are oblong in shape that comes to a tip. They are 2- 6 centimetres long and between 1-4 centimetres wide.

Flower: The flowers range from white to dark pink and grow in pairs. Like the other invasive Honeysuckles, the flowers are tubular. They are also 1.5-2cm long with 5 petals.

Image Credit: Missouri Botanical Garden

Stems: The Tatarian Honeysuckle is also hollow and has brown back with a hint of green. As the plant ages, the bark will appear shredded. The branches will be hollow between the nodes and are either grey or a yellow brown.

Image Credit: Illinois Wildflowers 

Fruit: The fruit are berries that are between 5-7 millimetres wide. The berries are usually red, though they can be yellow on rare occasions.

Image Credit: Getty Stewart

Height: Tatarian Honeysuckles will reach up between one to two meters in height.

Additional Information: The shrub is deciduous and prefers moist wooded areas. The stems where the fruit and flowers are will be longer than those with leaves.

*It is important to note that Honeysuckles can hybridize which can make identification challenging.

Invasive Honeysuckle Look-Alikes

Invasive Honeysuckle can be distinguished from the native bush honeysuckle in a few ways.  Invasive Honeysuckles typically have hollow stems, while the native will have solid stems. In addition, invasive Honeysuckle shrubs will usually have a light brown pith, whereas the native species will be a darker brown . One useful identification feature is the timing of the plant leafing out. Invasive Honeysuckle leaves emerge earlier in the season and will keep the leaves later than other native shrub species.

Bush Honeysuckle (Diervilla lonicera): The Bush Honeysuckle has yellow flowers that bloom in the summer and appear in small clusters. In addition, the leaves of the Bush Honeysuckle are dark green and toothed.

 

Image Credit: Walter Muma

Invasive Honeysuckle Management and Removal

As with any invasive species, it is important to be aware of existing species in the area and to consider the surrounding environment before deciding what course of action is best.

  • The first priority should be to prevent the spread of the invasive Honeysuckles by removing outlying or isolated patches.
  • Hand pulling can be effective for removing small plants, however, it should be done in the fall.
  • Medium plants can also be pulled when done carefully due to their shallow root system.
  • Larger plants require level tools and/or shovels to remove manually.
  • Unlike many other invasive species, Honeysuckles can be left where they were pulled so long as the roots are exposed to air.
  • When the Honeysuckles are pulled, the site should be checked regularly for new plants sprouting up.
  • Alternatively cutting and/or clipping the shrub can be effective, however, this needs to be done over three to five years and should not be done in winter.
  • As with other invasive species cutting the berries off and properly disposing of them can also help minimize spreading when removing the shrub is not an option.
  • As with any invasive species removal, it is important to mulch and or replant the area with native species soon after the removal.

Sources:

http://www.ontarioinvasiveplants.ca/wp-content/uploads/2016/06/OIPC_BMP_Honeysuckle.pdf

http://ontariotrees.com/main/species.php?id=2134

http://www.invadingspecies.com/invasive-honeysuckles/

http://www.invadingspecies.com/invaders/plants-terrestrial/invasive-honeysuckles/

https://www.nps.gov/plants/alien/pubs/midatlantic/loma.htm

http://www.ontarioinvasiveplants.ca/wp-content/uploads/2016/06/OIPC_BMP_Honeysuckle.pdf

Plants of Southern Ontario, Richard Dickinson, 2014.


Periwinkle (Vinca spp.)

Introduced to North America as an ornamental plant Periwinkle is native to Europe and Asia. Like many invasive species, Periwinkle has few pests and diseases in North America to help control its population. This is in part due to the toxicity of the leaves to grazing animals. As a result, it is able to form dense mats on the ground, which can disrupt the amount of light getting to undergrowth and young native plants. Since Periwinkle is easily accessible for purchase at nurseries and can easily escape yards, it is a rather concerning plant that should be avoided in one’s garden.

Identifying Periwinkle

Leaves: The leaves of the Periwinkle plants are a shiny dark green. The leaves grow opposite to each other on the stem and have an elliptical shape that tapers on either end.

Image Credit: Invasive Species Council of BC 

Flower: The flowers are a violet-purple, though they can on rare occasions be white. These five petal flowers will show up in the early spring and are between five to seven and a half centimetres wide.

Image Credit: Invasive Species Council of BC 

Stems: The stems of the Periwinkle are slender, trailing and can grow between one to two meters long.

Image Credit: Invasive Species Council of BC 

Periwinkle Look-Alikes

The main look-alikes for the Periwinkle plant are the Bigleaf Periwinkle, the Madagascar Periwinkle, and the Winter Creeper. However, each of these plants are also invasive in parts of the United States and should be removed when found in Canada.

Periwinkle Management and Removal

  • One of the more effective ways to remove Periwinkle is to pull it up, dig it out, or rake it. However, it is important to ensure that the root system is also removed.
  • After the plants have been removed, tarping can be beneficial in preventing seeds or plants from growing back.
  • Any plant material should be placed in a black garbage bag and left to ‘cook’ in the sun for 1-3 weeks.

Sources:

http://homeguides.sfgate.com/kill-periwinkle-killing-everything-else-21943.html

https://www.nps.gov/plants/alien/pubs/midatlantic/vimi.htm

http://www.ssisc.info/home/periwinklehttp://www.invadingspecies.com/invasive-ground-covers/


English Ivy (Hedera helix)

Introduced as an ornamental plant from Europe, English Ivy has since established itself as an invasive species in British Columbia, Ontario, and various States. As an incredibly adaptable plant with no predators, English Ivy has been able to spread with ease, aided by their continued prevalence as a garden plant. Their ability to grow and spread in shade, sun, and in any type of soil is another problematic part of the English Ivy. When the English Ivy grows as a ground cover it can block out the light for young plants and seeds that are below its growth. In addition, English Ivy can kill lower branched trees when it climbs onto them and may carry Bacterial Leaf Scorch, which can damage Elms, Oaks, and Maples.

Identifying English Ivey

Leaves: The leaves have a lobe-shape and are a dark shiny green with a light green vein that can be seen through the top of the leaf. The leaves grow alternately. Since the species has been bred into different variations of the plant, leaves will vary in size.

Image Credit: Invasive Species Council of BC 

Stems: The vine will either spread across the ground or will grow upward on other plants and structures.

Image Credit: Margaret’s Garden

Flowers: While it may vary depending on the type, the most prevalent English Ivy will not have flowers.

Height and Diameter: While the height may vary based on how the plant grows, old plant stems can be up to five inches thick, though they will typically be much smaller.

Image Credit: King County

Additional Information: As English Ivy climbs they will create small tendrils that will exude a glue like substance that allows it to securely attach to substances.

English Ivy Look-Alikes

Winter Creeper: Unlike the multi-lobed leaf of the English Ivy, the Wintercreeper has oval leaves. The Wintercreeper is also an invasive species.

Image Credit: Bill Johnson and NPS Government 

Poison Ivy: When young, Poison Ivy plants can appear similar to English Ivy. Poison Ivy will have three separate leaves that can look like that of English Ivy when they overlap. However, they will not have the same white veins throughout the leaves and will be three distinct leaves instead of one. It is also possible to distinguish English Ive from Poison Ivy through the root systems, however, it is not advisable to touch the Poison Ivy to check.

Image Credit: Pet Poison Helpline 

English Ivy Management and Removal

  • Physically removing with shovels or by hand is one of the more effective methods of control due to the shallow roots and strong stems.
  • It is more important to remove the full root system of the young plants than the old as the old plants are less likely to regrow.
  • If an English Ivy is climbing your tree, the lower leaves and branches of the vine should be removed.
  • The vines higher up on the plant can also be killed by cutting the root system. It is important to make sure that any Ivy is removed from the base of the tree to prevent it from re-growing.

Sources:

http://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/english-ivy.aspx

http://www.fosc.org/EI-Look-Alikes.htmhttps://treecanada.ca/en/resources/tree-killers/plants/english-ivy/


Emerald Ash Borer (EAB)

The Emerald Ash Borer (EAB) is an invasive beetle that was introduced to Ontario and the United States from Asia. Though EAB was first identified in Ontario in 2002, it was likely here for several years already. The beetles have been incredibly damaging to Ash trees as the adults will eat the leaves and then lays eggs under the bark. When the eggs are ready to hatch, the larva will eat at the living tissues under the bark until they are old enough to exit. This extensive damage under the bark is what will ultimately kill the tree. One of the main methods of spreading of the Emerald Ash Borer has been the movement of infected wood.

Identifying Emerald Ash Borer

Eggs: When freshly laid, the eggs will be a cream colour, while older eggs are a red brown colour. Regardless of how recently the eggs were laid, they are about 0.6 mm wide and 1mm long. However, the eggs are quite hard to see as they are typically in the upper parts of the tree and in the cracks along the bark, and under pieces of the bark.

Image Credit: Connecticut Tree Protective Association 

Larva: The larva will grow twenty-six to thirty-two millimetres long. They have a pale cream body that can also appear as a light green. They have a small brown head. The larva can be found underneath the bark in the summer. Just before the larva progresses onto being a Pupa, it can be seen with a ‘ J ’ shaped body from September until the end of Winter.

Image Credit: Connecticut Tree Protective Association 

Pupa: The pupa will start off as beige, however, it will eventually become a darker brown in latter stages of growth. They can be seen under the bark in this stage from April until July.

Image Credit: Connecticut Tree Protective Association 

Exit Holes: Adult beetle exit holes will be shaped like a capital D and 4 millimetres wide.

Image Credit: Ojibway Nature Centre

Adult Beetles: The fully-grown beetle will be a glossy emerald to coppery green colour with large kidney-shaped black or brown eyes. The EAB will be 3 millimetres wide, and 7-8 millimetres long. The adults will typically be seen around Ash trees from early June until late August.

Image Credit: Connecticut Tree Protective Association 

Other Signs: The following is a list of other signs of an Ash tree being infected with Emerald Ash Borer.

  • Underneath the bark the larva will have eaten the sapwood in a zigzag shape.
  • As woodpeckers will eat the larva under the bark, woodpecker damage to an Ash tree is a telltale sign of EAB.
  • Defoliation and the growth of epicormic (secondary shoots) at a branch node or lower down on a tree are signs that an Ash tree is infested and under stress.

Image Credit: Purdue University

Emerald Ash Borer Look-Alikes

Bronze Birch Borer: As its name suggests this beetle will attack Birch trees that are already under stress. As it has a similar shape and also leaves a ‘ D ’ shaped hole. The main way to tell them apart is to see if they were found or around a Birch tree (Bronze Birch Borer) or an Ash Tree (EAB). In addition, the adult Bronze Birch Borer has a bronze appearance, while the EAB has a glossy emerald look.

Image Credit: Ken Gray and Oregon State University 

Six-Spotted Tiger Beetle: While the six-spotted tiger beetle can have a similar appearance to the EAB due to its bright green colour, there are several noticeable difference. The adult Six-spotted tiger beetle is about .5 inch long and will live on the ground. The backside of the beetle will also be more of a squat shape than that of the EAB.

Image Credit: HGTV 

Two-Lined Chestnut Borer: This beetle attack stressed and dying Oak trees. Unlike the EAB the Two-lined chestnut borer will be darker with two lines on their backs.

Image Credit: Purdue Extension 

Emerald Ash Borer Removal and Management

Ash trees infested with the Emerald Ash Borer on public property within the Town of Oakville can be reported to Service Oakville at Phone: 905 845 6601 or Email: serviceoakville@oakville.ca

Removal of any tree over 15cm or more in diameter on private property in Oakville is subject to the Town of Oakville’s Private Tree Protection Bylaw.

While there is not much that can be done for an individual tree once EAB has become established, actions such as avoiding the transportation of infested wood are critical to stop the spread of EAB.

Sources:

http://www.oakville.ca/assets/general%20-%20residents/DetectingEABDamage-VisualGuide.pdf

http://www.emeraldashborer.info/documents/E-2944.pdf

Please note that the invasive species information provided on this page is provided for informational purposes only. Please consult the Invading Species Awareness Program or Ontario Invasive Plant Council for more detailed information and be sure to obtain necessary permissions from private property owners and to investigate and adhere to all applicable laws, bylaws and up-to-date management guides before undertaking any invasive species management activities.

Learn more:

Invasive Species: What are they?

Reporting Invasive Species

Invasive Species: Minimize Your Impact