Invasive species

Species which are quick to reproduce and spread, and which thrive in a broad range of habitat conditions, can often out-compete other species. These species are called “invasive” due to their aggressive colonisation of new spaces. Although some native species could be considered invasive, they are usually kept in check by the natural balance of their local ecosystem, and are not of great concern compared to non-native invasive species. Humans have transported many species to new lands, whether deliberately in the case of livestock, pets, crops and garden plants, or inadvertently in the case of many species commonly regarded as pests. These non-native species may have no local predators to control their spread, or may have devastating effects on local species which have not adapted to resist them. They can have serious impacts on the ecological balance of their new home.

Many non-native invasive species have already reached Ottawa. Garlic mustard, swallow-wort (also known as dog-strangling vine), common buckthorn and glossy buckthorn are common in many of our natural areas, crowding out the native species that should be there. Zebra mussels, Eurasian water-milfoil and flowering rush are thriving in our rivers. Other threats, such as the Asian long-horned beetle, are moving this way. Some species are still actively introduced, such as Norway maple and Amur maple, which are both popular landscape trees due to their attractive foliage and their ability to survive in highly urbanised environments. Others, such as the emerald ash borer that is decimating our city’s forests, are the subject of intensive research to find ways to control or eliminate them.

Wild Parsnip, Poison Ivy, and Giant Hogweed are commonly found in areas of uncultivated land, roadside ditches, nature trails, woodlots, and in some cases, on rural and residential property.  Under the Ontario Weed Control Act, the City is responsible to take some action regarding the control of Wild Parsnip, Poison Ivy and Giant Hogweed on city property. Private property owners are responsible for removing these plants from their own property. These plants are of public health concern because touching them or their sap can result in painful skin rashes and burns.  If you decide to take measures to control these plants, regardless of the method used, wear protective clothing and goggles to cover exposed skin and protect your eyes.  

Residents can help control invasive non-native species by becoming aware of them and acting to prevent or limit their spread. When camping, boating or cottaging, avoid transporting firewood or live bait into or out of the area, and clean all equipment thoroughly to remove seeds and other hitch-hikers. Never release unwanted pets into the wild. Choose native plants for landscaping where possible, and never plant non-native invasives (see some examples listed below) near natural areas. Ask your local nurseries and plant suppliers about which native species are best for landscaping, or use this handy ‘grow me instead’ guide.
 

Garden plants to avoid

The following popular garden plants are non-native invasives that should not be planted near natural areas:

• Amur maple – Acer ginnala
• Black locust – Robinia pseudoacacia
• Bugleweed – Ajuga reptans
• Creeping Jenny (moneywort) – Lysimachia nummularia
• Common and Japanese barberry – Berberis vulgaris and B. thunbergii
• Dame’s rocket – Hesperis matronalis
• Day lily – Hemerocallis fulva
• English ivy – Hedera helix
• European linden – Tilia cordata
• European mountain-ash – Sorbus aucuparia
• Goutweed – Aegopodium podagraria
• Honeysuckle, including Amur’s, Bell’s, European fly, Morrow and Tatarian (or Tartarian) – Lonicera maackii, L. X bella, L. xylosteum, L. morrowii and L. tatarica
• Japanese Knotweed - Fallopia japonica
• Lily of the valley – Convallaria majalis
• Oriental bittersweet – Celastrus orbiculatus
• Miscanthus grasses – Miscanthus sinensis and Miscanthus sacchariflorus
• Norway maple (including red-leaved varieties) – Acer platanoides
• Periwinkle – Vinca minor
• Spotted deadnettle – Lamium maculatum

Plants not permitted in City rights of way

View a list of non-native invasive plant species that are not permitted to be used for landscaping within the City’s right of way:

• Use and Care of Roads (By-law No. 2003-498) | City of Ottawa

For more information on how to dispose of invasive species, please go to Waste Explorer | City of Ottawa.

For more information on invasive species:

• Invasive species in Ontario
• Ontario's Invading Species Awareness Program
• Ontario Invasive Plant Council

Public notice of herbicide use

The City of Ottawa intends to control wild parsnip in areas city-wide along rural and suburban roadsides. Spot spraying will continue throughout the summer months as needed within the City of Ottawa.

The program will use Clearview Herbicide (PCP #29752, containing aminopyralid and metsulfuron-methyl), Navius FLEX (PCP#30922, containing metsulfuron-methyl and aminocyclopyrachlor) and Gateway adjuvant (PCP# 31470, containing mineral oil – paraffin base (adjuvants), surfactant blend) under the Pest Control Products Act (Canada).

Treatment for wild parsnip will commence on May 27, 2024 weather permitting, and will end on October 31, 2024. The City has retained the services of Wagar & Corput Weed Control Inc to apply the herbicide.

For further information, please contact the City at 3-1-1.

Opting Out

If you own property adjacent to the areas being sprayed and choose to opt out of the program, please file an online opt-out request (one property per form) before July 24, 2024.

2024 Wild Parsnip Herbicide Strategy

Herbicide use locations

Wild Parsnip Strategy

The Public Works department has been proactively mapping out wild parsnip infestation levels across the city along roadsides, parkland and pathways. Each year, the wild parsnip infestation levels mapping is used to identify the control areas (roadside/parklands/pathways) for the upcoming year.

The integrated management strategy includes monitoring, mapping, the use of herbicides, mowing and evaluation. The herbicide Clearview was chosen in consultation with other Municipal and Provincial stakeholders and experts, and may impact other weeds/plants but should not impact trees or grass.  

Second year growth wild parsnip begins to dry up in August, so contact with the plant will be less likely to cause a reaction. However, the sap still remains inside the plant. Avoidance or personal protective gear, when handing the plant, is still recommended.

Wild parsnip (Pastinaca sativa)

Wild parsnip is an invasive plant that is increasingly common within the City of Ottawa in areas of uncultivated land, roadside ditches, nature trails, as well as on and surrounding rural and residential properties.

Wild parsnip may pose a health risk to humans. The plant sap contains chemicals that may cause skin and eye irritation and make the skin prone to burning and blistering when exposed to the sun. The blisters typically occur one to two days after contact with the plant. This can result in long-term scarring of the skin.

The best way to avoid contact with wild parsnip is to become familiar with what the plant looks like so you do not accidently come in contact with the plant. 

Identification

Wild parsnip is a highly branched plant, with hollow green stems. It has two growth stages: non-flowering leafy rosettes at ground level and 0.5 to 1.5 metre-tall flowering plants.

Early growth: In the first year of growth, low-growing non-flowering rosettes of leaves form with a cluster of spindly, compound leaves that resemble celery leaves.

In bloom: When wild parsnip is in bloom usually in the second and third year plants have tall, branched yellow flowering stalks that usually bloom in early June to late July.

Mature plant: Starting in August ‎the blooming plant will begin to turn brown and the leaves and stems will begin to dry up. This means that the toxic sap from the plant will also begin to dry up, and contact with the plant is less likely to cause a reaction. Once the plant is completely dry the seeds will fall to the ground.

Seeds are flat and round. It is a biennial plant, reproducing only by seed. The seeds can lie dormant for years making it even more challenging to control.

Early Growth

In bloom

Mature Plant

Education and public awareness

How to avoid the plant

•  It is recommended that the public stay on the groomed areas of parks, roadsides and pathways where there are less instances of wild parsnip.
•  When working around wild parsnip or when walking through dense vegetation, wear goggles, gloves, long pants and long-sleeved shirts. Thoroughly wash boots and  gloves with soap and water before taking off your protective clothing.
•  Children should be reminded not to pick wild flowers. Ensure children are able to identify wild parsnip in order to avoid exposure.
•  If you are exposed to the plant sap, wash the contaminated area(s) thoroughly as soon as possible, and seek medical attention if skin irritation occurs.

Public education

• An awareness post card will be distributed at public events such as fall fairs. The awareness postcard will also be distributed to City partners such as school boards, and Ottawa Public Health.
• Caution signs will been installed in areas where there are high levels of wild parsnip infestation. Staff will continue to install caution signs in areas where the public may reasonably expect to encounter wild parsnip, and the City encourages residents to be mindful of the plant when entering non-groomed portions of wooded and naturalized areas.
• Hard copies of the postcard or flyer are available by contacting 3-1-1.
• Staff will continue to work with Corporate Communications, Ottawa Public Health and other internal and external stakeholders to coordinate efforts related to health promotion and implementation of weed reduction strategies. Staff will also continue to make updates to the City’s website as they learn more about wild parsnip through the pilot project.
• For additional information, please consult the City of Ottawa’s website. Residents can also contact the Ottawa Public Health Information Line for more information about the health impacts of wild parsnip at 613-580-6744.

Wild Parsnip look-a-likes

Giant Hogweed (Heracleum mantegazzianum)

_{Photo courtesy of Ken Towle}

Stem:

• 2.5 to 5 m high
• Hollow, 5 to 15 cm thick
• Prominent purple blotches
• Distinct, coarse bristly hairs

Flowers:

• Large, white umbrella-shaped clusters 30 to 90 cm across
• Made up of 50 to 150 small clusters

Cow Parsnip (Heracleum maximum)

_{Photo courtesy of Lynda Shores}

Stem:

• 1 to 2.5 m high
• Hollow, 5 cm thick at base
• Green, few to no purple spots
• Soft and fuzzy hairs

Flowers:

• White umbrella-shaped clusters
• 10 to 30cm across, made up of 15 to 30 small clusters

Queen Anne's Lace (Daucus carota)

_{Photo courtesy of Chris Evans, Illinois Wildlife Action Plan}

Stem:

• 0.3 to 1.5 m high
• Green, 1 to 2.5 cm thick
• Covered with fine bristly hairs

Flowers:

• White flower cluster 5 to 10 cm across
• Pale pink before fully opened
• Often single purple flower in centre of cluster

Angelica (Angelica spp.)

_{Photo courtesy of Owen Williams}

Stem:

• 1.2 to 2.1 m high
• Purple or purple blotched
• Smooth (no hairs)

Flowers:

• Greenish-white globe-like flower clusters
• 8 to 25 cm across

On private property 

Strategies to remove wild parsnip include the digging out the plant roots, targeted mowing, the use of herbicides and ongoing monitoring.

Digging the root up: Residents that have a small infestation in a yard or garden (fewer than 100 plants) or who do not want to use pesticides can dig out as much of the taproot as possible with a sharp shovel or spade. Follow-up digging will be required every few weeks to deal with re-growth (if the taproot was not completely removed) or missed plants. DO NOT burn or compost wild parsnip plants that have been cut down or dug up. Plants and roots that have been removed should be placed in a dark plastic bag and placed in the sun if possible away from areas children or pets could access them. After the wild parsnip plant has been left in a black bag for one to two weeks in the sun, it can be collected through your normal waste collection as garbage, not as leaf or yard waste. The bags do not need to be labelled. The City is handling wild parsnip in accordance with the requirements of the Ministry of Environment.

Targeted mowing: Mowing can be effective if begun just after peak blooming, but before the seeds set in the late summer or early fall. Cut plants will likely re-sprout after mowing, so it is important to combine mowing with other control methods such as bagging and removing the plants, especially those that are flowering and spot spraying with an approved herbicide. Be especially careful when using mowers, weed whips, mechanical string trimmers as they can spray users with sap and bits of the plants, leading to redness and sometimes hundreds of blisters on exposed skin. Wear goggles and protective clothing when mowing.

Use of herbicides: When a weed such as wild parsnip is declared a noxious weed, both the City and residents are able to purchase herbicides to control it. This is not considered a cosmetic use of pesticides because this plant can pose a risk to people. For more information please go to the Ontario Ministry of the Environment, Conservation and Parks (MECP) website.

Monitoring: Long-term monitoring is important in keeping this weed under control, as seeds will continue to germinate for several years.

Other information

Reporting wild parsnip: Report wild parsnip, poison ivy or giant hogweed on city property by calling 3-1-1 or by reporting online.

Safety information: Important safety information on wild parsnip hazards, control and disposal is available on the Ontario’s Invading Species Awareness Program web site. 

Agricultural and Rural Affairs Committee Reports: March 3, 2016 Wild Parsnip Strategy

Education: The City of Ottawa has produced an informational postcard and factsheet that are available upon request. Please contact adopt@ottawa.ca to request copies. Supplies may be limited.

Description

Giant Hogweed is a serious invasive plant that poses a moderate threat to human health and safety. Giant Hogweed is primarily found along roads, streams and open areas. Plants reproduce well on disturbed sites, and prefer full sun and open habitat common along roadsides and ditches in rural areas.

This plant is poisonous. Hollow stem, leaves and plant hairs produce a sap if broken. Sap can cause serious skin inflammation on contact. If contaminated skin is exposed to sunlight a more serious reaction can occur including blisters, discolouration, and scars. If sap has contact with eyes, loss of vision, blindness or damage to eyes can occur.

Identification

Giant Hogweed flowers from June to August with white (sometimes pinkish) flowers in large clusters. It is often confused with several other plants which pose no health risk such as cow parsnip (1-2 m in height, fine hairs on stem creating fuzzy appearance, leaf less deeply cut and smaller with small hairs and flowers in more rounded clusters no more than 30 cm across); Angelica (1-3 m in height, smooth green-purple stem with no hairs, small leaflets no more than 60 cm, flowers rounded in softball-sized clusters up to 30 cm across).

It is a long-lived perennial plant and can take 3 to 4 years before it flowers only once. It can range in height from 1 to 5.5 metres. Plants produce huge leaves that are up to 1 metre in width. Leaves are deeply cut, with large lobes, and sharp teeth on all leaf margins.

It has sharp pointed bumps on stems and leaf petioles. Stems have reddish purple flecks and are often entirely purple at the base, mostly hollow and up to 10 cm in diameter. Stems and petioles are densely hairy.

How to Avoid Giant Hogweed Burns

• When working around Giant Hogweed or when walking through dense vegetation, wear goggles, gloves, long pants and long-sleeved shirts. Thoroughly wash boots and  gloves with soap and water before taking off your protective clothing.
• Children should be reminded not to pick wild flowers. Ensure children are able to identify Giant Hogweed in order to avoid exposure.
• If contact with skin occurs, avoid exposure to sunlight and wash immediately.
• If a skin reaction occurs, seek medical attention.

 Important safety information on Giant Hogweed hazards, control and disposal is available on the Ontario’s Invading Species Awareness Program web site

On private property

In the spring (early May), use a spade to remove as much of the root as possible. You may need to dig repeatedly to remove it completely.

In the summer (early July), remove plants without flowers by digging the stems and roots out and dry them thoroughly before disposing of them. To prevent seeds from growing and spreading, remove any flower heads before they ripen (when they are white).

On city property

Report Giant Hogweed, Wild Parsnip, and Poison Ivy on city property by calling 3-1-1 or letting us know with this on-line reporting form. Or call 3-1-1.  

To assist with controlling the spread of many harmful and invasive plants on city property, the City cuts the roadside grass throughout the summer months. Each rural roadside receives an average of two full cutting cycles and each suburban and urban roadside receives an average of six full cutting cycles.

If grass cutting does not successfully control these weeds and they still pose a public safety hazard, the City may choose to use herbicides. . . Herbicides are used in accordance with the provisions of the Ontario Pesticide Act, and may only be applied by a licensed applicator. The City will always post highly visible signs in the general area if an herbicide is used before it is applied and the sign will stay up for 2 days afterwards in compliance with provincial requirements. The name of the herbicide used along with the name and phone number of a person who can answer questions about the application is always written on these signs.

Poison Ivy is a harmful weed that is commonly found within the City of Ottawa in areas of uncultivated land, roadside ditches, nature trails, woodlots as well as on and surrounding rural and residential properties.

Poison Ivy may pose a health risk to humans. All parts of the plant contain a poisonous substance (urushiol) which causes an irritating inflammation of the skin, frequently developing blisters. About 50-60% of people are allergic to this substance.

The best way to avoid contact with Poison Ivy is to become familiar with what the plant looks like and stay away from it.

Identification

Poison Ivy can be found in clusters of three leaflets. Each leaflet grows on its own stem and connects to the main stem. Poison Ivy leaves and stems do not have thorns.  

How to Avoid Poison Ivy Rash

• When working around Poison Ivy or when walking through dense vegetation, wear goggles, gloves, long pants and long-sleeved shirts. Thoroughly wash boots and gloves with soap and water before taking off your protective clothing.
• Children should be reminded not to pick wild flowers. Ensure children are able to identify Poison Ivy in order to avoid exposure.
• If you are exposed to the plant, wash the contaminated area(s) thoroughly as soon as possible, and seek medical attention if skin irritation occurs.

Removing Poison Ivy from your property:

Poison Ivy is mainly spread by soil movement and contaminated equipment, but can still be found in private gardens. Minimizing soil movement and regular equipment washing can help prevent new introductions. Poison Ivy can be controlled by digging out the roots and stems as well as by the use of certain herbicides (chemical weed-killers). For more information on important safety, control and disposal methods, visit the Ontario Ministry of Agriculture, Food and Rural Affairs web site.

On City Property

Report, Poison Ivy, Wild Parsnip or Giant Hogweed on city property by calling 3-1-1 or let us know with this on-line reporting form. Or call 311.

Although noxious weeds generally establish themselves in areas of uncultivated or untraveled lands, there are circumstances where they may be found near travelled areas of City property such as parks and pathways.

To assist with controlling the spread of many harmful and invasive plants on city property, the City cuts the roadside grass throughout the summer months. Each rural roadside receives an average of two full cutting cycles and each suburban and urban roadside receives an average of six full cutting cycles.

If grass cutting does not successfully control these weeds and they still pose a public safety hazard, the City may choose to use herbicides. . . Herbicides are used in accordance with the provisions of the Ontario Pesticide Act, and may only be applied by a licensed applicator. The City will always post highly visible signs in the general area if an herbicide is used before it is applied and the sign will stay up for 2 days afterwards in compliance with provincial requirements. The name of the herbicide used along with the name and and phone number of a person who can answer questions about the application is always written on these signs. 

The Canadian Food Inspection Agency has issued a ministerial order to prohibit movement of firewood, and ash-tree products such as nursery stock, logs, branches and wood chips from areas of Ottawa and Gatineau to any other surrounding regions to limit the spread of Emerald Ash Borer (EAB).

Emerald Ash Borer is a non-native, highly destructive wood-boring beetle that feeds under the bark of ash trees. All species of ash are susceptible to attack, except mountain ash, which is not a true ash species. Since it was first identified in Michigan in 2002, EAB has killed millions of ash trees in Ontario and many parts of the United States. It poses a major economic and environmental threat to urban and forested areas. It was confirmed in Ottawa in 2008 and its impacts can be clearly seen spreading from the St. Laurent area. Since the insect spends most of its lifecycle under the bark of trees, it can be easily moved with firewood or other tree materials such as nursery stock, logs, brush and larger wood chips. This insect is able to fly, but since its spread has been primarily along major highways and transport routes, it is clear that humans are the main vector of dispersal.

What EAB does

Emerald Ash Borers normally have a one-year life cycle, but some can take up to two years to mature. EAB lays eggs on tree bark and in bark crevices starting in late May.

In its larva form, which resembles a caterpillar, Emerald Ash Borer feeds just under the bark of ash trees. This feeding disrupts the tree’s circulation of water and nutrients. The presence of even a few insects in a tree can kill it.

Top branches of ash trees usually die off first. Trees can lose half its branches in a single year. Once larvae finish feeding under the bark, they mature into adult beetles that chew their way out of the tree.

S-shaped grooves and D-shaped exit holes 3.5 – 4 mm wide caused by adult beetles photo courtesy Troy Kimoto, CFIA

• look for loss of leaves and dead branches in the upper part of ash trees
• unusually thin tree crowns
• branch and leaf growth in the lower part of the stem where growth was not present before
• unusually high woodpecker activity
• look for bark splitting, S-shaped grooves beneath the bark caused by larval feeding, and D-shaped
• exit holes 3.5 – 4 mm wide caused by adult beetles

Infested ash trees in North America generally die after two to three years, but heavily infested trees have been observed to die after one year.

Ash trees

Learn how you can identify Ash trees.

The City of Ottawa's Emerald Ash Borer Strategy

The City's Emerald Ash Borer (EAB) strategy includes treating trees with TreeAzin^TM, removing and replanting trees, proactive plantings, as well as public education to raise awareness regarding EAB and proper wood handling and disposal.

Selective tree injections 

The City is treating selected ash trees throughout the Ottawa region with TreeAzin^TM. TreeAzin^TM is a systemic insecticide produced from extracts of Neem Tree seeds (Azadiracta indica).  It is injected under a tree’s bark, directly into the conductive tissues, and moves upwards with the flow of water and nutrients.  TreeAzin^TM can be very effective at controlling EAB infestations but injections are required every two years and treatment does not ensure tree survival.  For more information on TreeAzin^TM, please visit the manufacturer’s website at http://bioforest.ca/.

Because of the large population of ash trees in Ottawa, it would be prohibitively expensive to inject every ash tree on city property. The City’s injection program, therefore, focuses on injecting ash trees that will receive the most benefit. The City’s injection policy aims to:

• Protect a mix of age classes to ensure diversity in the population of protected ash trees, and
• Provide ash tree protection in neighbourhoods with a high percentage of forest cover from ash species

Trees are assessed on an individual basis and considered for injection based on a number of factors including tree health, tree form and tree location.

Are you thinking of having your privately-owned ash tree injected?

Treating your ash tree can be a good investment when taking into account the cost for tree removal and replanting as well as the benefits urban trees provide including increased property value and energy savings.

Slow down the spread

Residents can help by:

• Learning to identify EAB and ash trees
• Reporting suspected outbreaks
• Not moving firewood out of Ottawa and Gatineau or into adjacent communities 
• Being aware of regulations for firewood and ash products 
• Not bring firewood to your cottage or campsites 
• Buying your firewood locally and know where your firewood originates 
• Obeying all ministerial orders issued by the federal government 
• Remembering, even after an infested tree has been cut down, EAB continues to live in the wood

Failure to obey a ministerial order can further put our forests at risk, and could also lead to prosecution and fines as high as $50,000.

Removal and disposal

The City is responsible for maintaining or removing City-owned ash trees (in City road allowances, municipal parks and natural areas). Trees will only be removed if they are highly infested with the Emerald Ash Borer (EAB) or if they become structurally unstable.

Private property owners are responsible for removing and disposing of affected ash trees on their properties. It is recommended that the owner use a certified arborist and ensure full compliance with the ministerial order for wood movement and disposal.

Home owners are still able to put leaves and branches under four inches in diameter and four feet in length out for curbside leaf and yard waste collection even if they are from ash trees. Residents can continue to bring their own leaf and yard waste to the Trail Waste Facility for free if it meets the above requirements. A fee will apply to contractors and residents bringing in material greater than four inches in diameter

Don’t move firewood

The human movement of infested materials such as firewood, logs, branches, nursery stock, chips or other ash wood is the most common way EAB has been spread. Adult Emerald Ash Borer can fly, but research indicates adults usually fly a short distance upon emergence. The City of Ottawa and the CFIA are asking the public not to move firewood or other wood materials. To reduce the risk of spreading forest pests, buy and burn firewood locally.

You can help by learning to identify EAB and ash trees and by reporting suspected outbreaks of the Emerald Ash Borer by contacting the CFIA at 1-866-463-6017 or e-mailing the City 311@ottawa.ca. For more information see the Ontario Ministry of Natural Resources’ EAB Site.