Tree Pests and Diseases

There are many different pests or diseases that can affect the health of our trees. Insects such as the Emerald Ash Borer (EAB), Cankerworm, Spongy Moth and Asian long-horned beetle, and diseases such as Oak Wilt can have devastating effects on the health of the urban forest.

Reducing the vulnerability of the city's urban forest to pests and diseases involves implementation of a wide range of urban forestry practices, including:

• Plant health care: site-appropriate tree species selection, young tree pruning, watering, and mulching;
• Improving tree habitat: increasing soil volumes, improving soil quality, reducing above and below ground completion for space and resources;
• Diversifying the urban forest: establishing underutilized and new native and non-invasive tree and shrub species;
• Improving knowledge and understanding of the urban forest: conducting a public tree inventory and improved species-based pest vulnerability analysis, increasing monitoring, species and stock suitability trials;
• Pest-specific management: development and implementation of targeted strategies to mitigate the effects of specific insects or pathogens.

Trees impacted by cankerworms

The most common trees that this species prefers to feed on are ash, basswood, beech, black cherry, red maple, sugar maple, red oak, and white oak. It will also feed on the leaves of apple, birch, boxelder, dogwood, elm, hickory, and many other hardwoods.

How to create a tree sticky band

Help reduce cankerworm populations. Creating a “Sticky Band” around your trees can help reduce cankerworm population and help keep our urban trees and forests healthy.

• Tools/resources:
  • 10 to 15 cm wide strip of insulation or cotton batting
  • Plastic wrap or a garbage bag
  • Duct tape or packing tape
  • A sticky substance, such as Tanglefoot™

1. Wrap the tree with polyester or cotton banding

Wrap a 10 to 15cm wide strip of polyester or cotton (quilt) batting around the trunk of the tree you are going to be banding - about five feet (1.5m) off the ground. Keep out of reach of pets and young children

2. Cover the wrap with plastic wrap or a garbage bag

Cover the polyester or cotton (quilt) batting with a sheet of plastic wrap or a garbage bag. Allow several inches of plastic above and below the insulation. For larger trees you may need to tape multiple bags together.

3. Tape the band covering to secure to tree

If you are using plastic bags or plastic wrap, tape the plastic to the tree with duct tape or packing tape. Please do not use nails or staples to attach the plastic to the tree as this will injure the tree.

4. Apply sticky substance to tree band

Spread a layer of a sticky substance, such as Tanglefoot^TM (non-toxic, not a pesticide, available at garden centres and hardware stores) as directed or petroleum jelly, on the plastic. This will make the cankerworms stick to the band.  Be sure to wear gloves as it is very sticky!

5. Inspect and maintain sticky band

Inspect the sticky material regularly and remove leaves, insects and other debris and reapply sticky material if required.

6. Remove sticky band at the end of the season

Bands should be removed by late spring and reapplied in the fall. It is important to remove the bands to prevent damage or discolouration of the bark.

Oak wilt is a vascular disease of oak trees, caused by the fungus Bretziella fagacearum that can damage and destroy an oak tree in a single growing season. The fungus grows on the outer sapwood of oak trees and damages the tree by restricting the flow of water and nutrients through the tree. All oak species are susceptible and at risk.

Oak wilt has spread throughout the Eastern United States and has been present since the 1940s. In 2023, oak wilt was confirmed for the first time in Canada in Niagara Falls and the Township of Springwater. While oak wilt has not been identified in Burlington, the City encourages residents to become familiar with the signs and symptoms of oak wilt in order to minimize the threat to oak trees locally.

Trees impacted by oak wilt

All oak species are susceptible and at risk. The red oak group (red, black, pin) is the most susceptible, with mortality frequently occurring within one growing season. Oaks in the white oak group (white, bur) are also affected but are more resistant.

As part of Burlington's Integrated Pest Management (IPM) program, Forestry staff assess sites annually across the city and conduct egg mass surveys to determine areas where natural processes can no longer keep pest population levels down on their own. Although healthy trees can generally withstand repeated defoliation, trees which are already in distress from problems such as acute drought, compacted soils, diseases or other pests may die. Generally, healthy trees which are defoliated in spring, will leaf out again by fall. Spongy moth populations tend to be cyclical, with peaks every 8-12 years, followed by dramatic population decline of the pest

Treatments are only used when populations exceed accepted thresholds. Treatment of the insect populations below threshold levels. The treatment option commonly used is BtK (Bacillus thuringiensis var. kurstaki), a bacterium found naturally in soils. BtK works only against larva of the target species of insect; it does not affect plants, animals or people. BtK is one of the few organic treatments acceptable to organic growers as it is a naturally occurring biological organism.

How to create a burlap tree band