Trees and Yards

Tree maintenance and protection is essential for the health of Caledon’s urban forests and landscapes.  Please contact Municipal Law Enforcement Services before destroying any trees within the Town of Caledon.

Private versus public trees 
Tree ownership, maintenance, and care responsibilities are dependent on the location of the tree(s) in question.  Trees are considered privately owned when more than 50 percent of the trunk’s diameter is on the private side of the property line. Trees are considered Town-owned when more than 50 percent of the trunk diameter on the Town’s side of the property line. 
 
If you are unsure as to the ownership of a tree(s), please refer to your property survey. If the tree(s) appears close to the Town property line or you are unsure, please call 3-1-1 to arrange an inspection by Town Operation Staff.  
 
Residents maintaining gardens that surround trees within Town-owned boulevards should review requirements outlined in the Encroachment By-Law and Clean Yards By-Law. More details can also be found on our Boulevards web page.  
Protecting woodlands 

Trees are an important part of Caledon's natural landscape, and from many of our significant woodlands. Our Woodlands Conservation By-law sets out practices to improve the health and stability of the woodlands.

If you need to remove or harvest trees from a woodland on your property, you will need to fill out an application for a  woodland permit. 

If you wish to sell harvested trees or are approached by a log buyer, consult a professional forester. To find more information, visit  selling trees in Ontario. 

 Please contact Municipal Law Enforcement Services before destroying any trees within the Town of Caledon.

Planting trees on your property

Benefits of Trees 

Planting trees on your property poses many benefits as they:  

  • clean our air;

  • provide oxygen;  

  • promote biodiversity;  

  • keep us healthy;

  • enhance property values; 

  • save energy costs; and 

  • help fight climate change. 
Help grow our tree canopy!  
Tree care guides and planting tips

When planting new trees on your property, consider referencing tree care guides to help ensure they survive and thrive in their new home.

Caring for existing trees

Promote healthy conditions  

You can promote a healthy environment for your trees by:   
Learn more

  • Learn more about various tree pests, pathogens (diseases), and invasive species by navigating the dropdowns below. 

  • To learn more about trees that are native to Ontario visit the Ministry of Natural Resources and Forestry Tree Atlas. 

Threats to trees

Damage to trees

Mechanical injury 

Mechanical injury to trees includes damage to the bark, branches, leaves or roots. Regardless of the type or amount of damage that has occurred, risk of pest and disease introduction increases dramatically and can later impact the health of a tree.  
 
Mechanical injury can be caused by: 

  • lawn mowers and lawn maintenance equipment; 

  • vandalism or carvings into the tree; 

  • installing signs, bird houses, or exterior lighting on a tree; 

  • planting a new tree too deep into the ground;

  • soil compaction around the base of the tree's trunk;

  • improper mulching (e.g., “volcano” mulching);

  • choking or girdling from support structures (wires and stakes);

  • flowerbeds; and 

  • improper pruning.

Tree pests and pathogens (disease)

Terminology

Native Species 

Native species are species of plants and wildlife that are found naturally in Ontario and local areas.  

 
Non-native species  

Non-native species are introduced to a new geographic area and can establish a surviving population, but do not cause environmental, economic nor social impacts. Not all non-native species are considered invasive. Non-native species may also be termed as “exotic species”. 

 
Invasive Species  

Invasive species are non-native species that are introduced to a new geographic area and establish, survive, and cause environmental, economic or social impacts. Severity of invasion and impacts of an invasive species will vary depending on biological characteristics of the species, environmental conditions, spread and amount of disturbance in the area. 

 

To learn more about the impacts of invasive species (including plants, animals, insects, and pathogens to disease) visit the following resources: 

  • Invasive Species Centre – Learn 
Aphids (Native, Non-native, and Invasive)

Aphids are small sap-sucking insects that feed on vegetation tissues using piercing mouth parts. Thousands of aphid species are found in North America, and they are more commonly seen as pests in the agriculture and horticulture industries. This is due to host specificity of aphids, however, urban forests and trees are also known to host various native, non-native, and invasive aphid species. 
 
Aphids do not cause significant damage to trees but can increase vulnerability to insects and disease.  
 
Signs and Symptoms  

  • Presence or accumulation of honeydew (a sticky sap-like excretion from the insect) on branches, surrounding trees and private property. 

  • A black, sooty mold can grow on honeydew and can prevent leaves from getting nutrients from the sun. 

  • Ants may appear in high numbers to eat the honeydew and carry aphids to new areas. 

  • Leaves of trees may curl, branch buds may be distorted and die back might occur. 

What you can do?

  • Attempt to spray the aphids off the tree with a hard jet of water from a hose.  

  • Avoid using broad-spectrum insecticides on your property that kill natural predators of aphids. 

  • Use a sticky barrier band around the base of the tree to stop ants from transporting or relocating aphids. 

  • Encourage ladybugs into your garden as they feed on aphids. 

  • Consider chemical treatments using a registered biological insecticide or insecticidal soap application. 

  • If infestations are occurring on a Town-owned tree, call 3-1-1 for an inspection by the Town’s Forestry Supervisor or Invasive Species Coordinator. Depending on infestation severity, the tree may be selected for treatment by the Town.

Note: For safe and effective chemical treatment, property owners should consult with their chosen tree care professional to determine the best way to manage trees on their own property.

 

Learn More 

For more information on Aphids see the resources below:  

  • Health Canada – Aphids 

Asian longhorned beetle (Invasive)

Note: Asian longhorned beetle has been reported and eradicated in the Mississauga and Toronto areas in the past, but has not been reported in the Caledon area. If you think you have seen Asian longhorned beetle report it to the Canadian Food Inspection Agency, the Invasive Species Centre ,or on EDDMaps.

Asian longhorned beetle (ALB; Anoplophora glabripennis) is an invasive beetle species that feed on the leaves and twigs of trees. ALB's prefers maple trees, however they can also target birches, poplars, willows, and other hardwood tree species.


ALB has four life stages (adult, eggs, larvae, pupae). Adults are black with prominent white spots and will chew shallow holes into the bark of the tree to place a single egg. A creamy white larva hatches from the egg and feeds by tunneling through the trunk of the tree until it enters its pupae phase. Adults will emerge from the pupae, creating obvious (15-20mm) exit holes in the bark of the tree.  

  

Signs and symptoms

  • Leaking sap.
  • Large exit holes in the bark of tree. 
  • Yellowing leaves.
  • Branch dieback.
  • Premature leaf drop.
  • Oval-shaped egg pits in the trunk of the tree.

What can you do?

  • Report sightings of ALB.
  • Inspect your tree(s) for pest and pathogens using the Invasive Species Centre and Canadian Food Inspection Agency’s  Tree Check Form. 
  • Don't move firewood! Buy and burn firewood locally.

 

Learn More

For more information on the Asian longhorned beetle see the info bellow:
Hemlock woolly adelgid (Invasive) 

Note: Hemlock woolly adelgid has been reported in Ontario, but not in the Caledon area. If you think you have seen hemlock woolly adelgid report it to the Canadian Food Inspection Agency, the Invasive Species Centre ,or on EDDMaps.
 
Hemlock woolly adelgid (HWA, Adelges tsugae) is an invasive aphid-like insect that attack and kill hemlock trees. The adelgids attach to the needles on the branches of the tree and feed on the nutrients and water storage using piercing mouth parts. The primary host of HWA is the Eastern Hemlock (Tsuga canadensis) however, it is known to impact other hemlock species, including ornamental varieties.  
 

HWA has a complicated life cycle that allows for multiple generations and life stages within the same year.

 

Signs and Symptoms 

  • White “woolly” moving sacs at the base of hemlock needles. 

  • Premature branch bud and shoot dieback.

  • Premature needle loss.

  • Dieback of twigs and branches.

  • Discoloration of needles.

  • Severe infestations can lead to the death of the tree.  

 

What can you do? 

  • Report sightings of HWA.  

  • Monitor hemlock trees on your property for HWA. 

  • Promote healthy tree conditions by watering trees during dry seasons and avoiding mechanical injury where possible. 

  • Avoid hanging bird feedings near or within hemlock trees or stands. 

  • Don't move firewood! Buy and burn firewood locally.

  • Inspect your tree(s) for pest and pathogens using the Invasive Species Centre and Canadian Food Inspection Agency’s  Tree Check Form. 

 
 Learn More 

For more information on Hemlock woolly adelgid see the resources below:  
Spongy moth (Invasive) 

The spongy moth (Lymantria dispar dispar) is an invasive moth species from Europe that has spread and established itself in southern Canada, as well as eastern and central United States. It is a forest pest of concern because of the ability of the moth’s larvae (caterpillars) to defoliate trees (consume leaves). Healthy trees can typically survive severe defoliation by the spongy moth larvae; however, repeated defoliation stresses trees and makes them more vulnerable to other forests pests, diseases and drought.

Though the spongy moth accepts many tree species as its host, some of the more-preferred hosts include oak, maple, alder, beech and birch species. Defoliation from larva feeding on leaves typically stops in early summer when the caterpillars have entered the pupae (cocoon) phase for one-to-two weeks. 

Male and female adult moths then hatch from pupae around mid-July, but do not feed on the leaves of the trees. Instead, the adult moths spend their short-lived lives reproducing and laying egg masses to restart the life cycle.

Signs and Symptoms  

  • Small caterpillars (larvae) hanging on silk strands in and around infested trees. 

  • Egg masses found on tree bark and surrounding infrastructure. 

  • Leaves with holes or completely defoliated trees.  

 
What can you do? 

  • Report a sighting to our Spongy Moth Tracking Form.  

  • See the Town’s How to manage spongy moth on your property.  

  • If you see spongy moth on Town property, please contact Service Caledon at 3-1-1, email info@caledon.ca. It will be investigated by the Town Invasive Species Coordinator or by an Arborist.

  • Don't move firewood! Buy and burn firewood locally.

 

Learn More 
To lean more about the spongy moth and how the Town is managing it visit the Town of Caledon’s Spongy Moth Page.
Spotted lanternfly (Invasive) 

Note: Spotted lanternfly is not known to occur in Ontario or Canada at this time. If you think you have seen spotted lanternfly report it to the Canadian Food Inspection Agency, the Invasive Species Centre ,or on EDDMapS. 
 
Spotted lanternfly (SLF; Lycorma delicatula) is an invasive planthopper species that kills plants by sucking the sap from leaves and stems. SLF feed in swarms on more than 70 species of trees and plants, including cultivated grapes, fruit trees, black walnut, maples, and oaks. 
 

SLF has three life stages, eggs (in egg masses), nymphs, and adults.  

 

Signs and Symptoms 

  • Presence or accumulation of honeydew (a sticky sap-like excretion from the insect) on branches, surrounding trees and property. 

  • A black, sooty mold growing on honeydew covered surfaces. 

  • Muddy grey egg masses on hard surfaces. 

  • Swarming of nymphs and adults on host trees. 
     

What can you do? 

  • Report sightings of SLF. 

  • Avoid planting tree of heaven, the preferred host plant of SLF.

  • Manage or remove tree of heaven plants on your property. 

  • Check hard surfaces for egg masses frequently, especially when leaving or transporting materials from areas of known SLF detections or quarantine zones. 

  • Don't move firewood! Buy and burn firewood locally.

  • Inspect your tree(s) for pest and pathogens using the Invasive Species Centre and Canadian Food Inspection Agency’s  Tree Check Form. 

 

Learn More 

For more information on spotted lanternfly see the resources below:  
Oak wilt (Invasive) 

Note: Oak wilt has been reported in Ontario in 2023, but has not been reported in Caledon. If you think you have seen oak wilt report it to the Canadian Food Inspection Agency, the Invasive Species Centre ,or on EDDMapS. 
 
Oak wilt is a disease that is caused by the fungus Bretziella fagacearum. When the fungus establishes on the bark of the tree, it blocks the flow of water and nutrients throughout the tree. In severe cases an infestation can kill the tree. All species of oak tree are potential hosts of this disease, however red oak (Quercus rubra) is more susceptible than other oak species. 
 
Oak wilt is spread both above ground by beetles carrying the fugus and underground through root networks.  

 

Signs and Symptoms  

  • Wilting or dieback in the leaves of the trees, starting at the top of the tree eventually moving downwards. 

  • Discoloration in leaves will begin at the outer edge of the leaves and work in towards the middle.  

  • Premature leaf fall (oaks typically hold on to leaves until late fall or even over winter). 

  • White, grey, or black fungal mats, also referred to as “pressure pads”, under the bark that can emit a fruity smell. 

  • Vertical bark cracks in the trunk and large branches as a result of the fungal spore mat exerting outward pressure on the bark. 

What you can do? 

  • Report sightings of oak wilt.  

  • Do NOT prune oak trees from April to July. If pruning must occur, or if a tree is injured, apply a thin layer of wound paint immediately. 

  • Don't move firewood! Buy and burn firewood locally.

  • Inspect your tree(s) for pest and pathogens using the Invasive Species Centre and Canadian Food Inspection Agency’s Tree Check Form. 

 
Learn More 

For more information on oak wilt see the resources below:  

  • Invasive Species Centre – Oak Wilt  

  • Ontario’s Invading Species Awareness Program – Oak Wilt  

  • Canadian Food Inspection Agency – Oak Wilt  
Tree Check Form

  • Inspect your tree(s) for pest and pathogens (disease) using the Invasive Species Centre and Canadian Food Inspection Agency’s Tree Check Form. 
Learn more about insect pests and pathogens:  

For more information on pests listed above, and other pest/pathogens of trees visit the following links: 

Invasive trees and plants 

Terminology

Non-native species

Non-native species are introduced to a new geographic area and can establish a surviving population, but do not cause environmental, economic, or social impacts. Not all non-native species are considered invasive. Non- native species may also be termed as “exotic species”.


Invasive Species

Invasive species are non-native species that are introduced to a new geographic area and establish, survive, and cause environmental, economic or social impacts. Severity of invasion and impacts of an invasive species will vary depending on biological characteristics of the species, environmental conditions, spread and amount of disturbance in the area.

 

To learn more about the impacts of invasive species (including plants, animals, insects, and pathogens) visit the following resources:

 

Noxious Weeds/Species

A noxious weed is a plant species that has been designated under the Weeds Control Act. To obtain this designation the plant is one that is difficult to manage and impacts agriculture, negatively impacts the health and wellbeing of livestock, or poses a risk to health and well being of people.

 

To learn more about the Weeds Act and the noxious weeds visit the following resources:

 

Restricted or Prohibited Species

Restricted or Prohibited Species are two classes of invasive species regulated under the Ontario Invasive Species Act.  It is illegal to import, possess, deposit, release, transport, breed/grow, buy, sell, lease or trade species listed as prohibited or restricted within the Invasive Species Act.


To learn more about Regulated Invasive Species visit the following resources:
Woody invasive plants

Woody invasive species (trees and shrubs) pose risk to Caledon’s forests and natural landscape health by out competing native plants and trees.

Some invasive tree and shrub species that occur in Caledon and Ontario include the following species:

  • Common buckthorn (Rhamnus cathartica)
  • Tree of Heaven (Ailanthus altissima)
  • Norway Maple (Acer platanoides)
  • Manitoba Maple (Acer negundo)
  • White Mulberry (Morus alba)
  • Siberian Elm (Ulmus pumila)
  • White Poplar (Poplus alba)
  • Winged Euonymus or "Burning bush"  (Euonymus alatus)
Herbaceous invasive plants

Invasive trees and shrubs are not the only plants that threaten the health of our urban forests and natural landscapes. Other plants of concern include, but are not limited to the following species:

  •  Giant Hogweed (Heracleum mantegazzianum: Invasive & Noxious)

Caution: Sap from giant hogweed plants can be extremely dangerous to humans if it comes into contact with skin or eyes. Severe burns can develop when sap exposed skin is in direct sunlight. Follow best management practices when managing giant hogweed on your property.

If you find giant hogweed on Town property, please call 3-1-1 to arrange an inspection by Town Operation Staff. 

  • Wild Parsnip (Pastinaca sativa: Invasive & Noxious)

Caution: Sap from wild parsnip plants can be extremely dangerous to humans if it comes into contact with skin. Severe burns can develop when sap-exposed skin is in direct sunlight. Follow best management practices when managing wild parsnip on your property.

If you find wild parsnip on Town property, please call 3-1-1 to arrange an inspection by Town Operation Staff. 

  • Dog Strangling Vine Species  (Vincetoxicum spp.: Invasive, Noxious, & Restricted)
  • Miscanthus Species (Myscanthus spp.:Invasive)
  • Knotweed Species (Reynoutrina spp.: Invasive & Restricted)
  • Common Reed or Invasive Phragmites (Phragmites australis: Invasive & Restricted)
Learn more about invasive plants

For more information on invasive plants, their impacts, and best management practices see the following resources: