Forestry

We have finished our Gypsy Moth treatments for 2018. 

The trees in Mountainside Park and individual trees in LaSalle Park have been treated. Levels of infestation throughout the rest of the city are not anticipated to cause serious risk to the trees and do not warrant treatment at this time.

As part of Burlington's Integrated Pest Management (IPM) methodology, Forestry staff will continue to assess sites across the city annually and conduct egg mass surveys to determine areas with high potential of significant tree risk and will take appropriate action as warranted.

European Gypsy moth, Lymantria dispar, is an introduced pest that impacts trees when larvae emerge in spring and the caterpillars feed on leaves causing defoliation. Oaks are the preferred host species of tree.

As part of Burlington's Integrated Pest Management (IPM) methodology, Forestry staff assess sites annually across the city and conduct egg mass surveys to determine areas with high potential of significant tree risk. Forestry staff also undertake removal of egg masses where possible. Although healthy trees can generally withstand a couple years of repeated defoliation, trees which are already in distress from problems such as acute drought, diseases or other pests may die. Generally, healthy trees which are defoliated in spring, will leaf out again by fall. Gypsy moth populations tend to be cyclical, with peaks every 8-12 years, followed by dramatic population decline of the pest.

Treatment of the insect is aimed at keeping larvae populations below risk levels to the tree. Two options are commonly used: Btk (Bacillus thuringiensis var. kurstaki), a bacterium found naturally in soils, or TreeAzin, the common treatment for ash trees infested with Emerald Ash Borer (EAB). Burlington will not be undertaking aerial applications of Btk.  Mountainside Park is the only location to be treated with truck-mounted spray applications. This application is scheduled for May. Btk works only against the larvae of the target species of insect; it does not affect plants, animals or people. Btk is one of the few treatments acceptable to organic growers as it is a naturally occurring biological organism. A communication to local residents surrounding Mountainside Park will be delivered in advance of the treatment. 

LaSalle Park has a few individual trees which will be treated with TreeAzin, similar to the treatment of ash trees for EAB.  

Forestvale Park, which had been impacted about a decade ago with gypsy moth, is showing insignificant levels of egg cases, so no treatments are needed in 2018.

It is sad to see trees being cut down along our streets and in our woodlots. Unfortunately the Emerald Ash Borer (EAB) is an invasive insect that was introduced to North America on packaging materials and has ravaged our urban forests, killing hundreds of millions of ash trees across North America. Ash trees were considered a favourite street-tree decades ago when many communities were developed. Once infested, the trees quickly become brittle, drop branches and die. The City of Burlington is tasked with managing the EAB infestation without assistance from federal or provincial levels of government so the financial burden is placed on the local taxpayers. Staff are working diligently to manage the crisis through planned removals and replanting on streets, while optimizing tight fiscal resources.

Ash tree removals are necessary along streets, in parks and in woodlands to protect people and property. In Burlington, more than 13 per cent of our urban trees are ash so we must remove thousands of trees. Some municipalities are harder hit though, with over 20 per cent of their tree populations dying.

We are replacing ash trees along streets on a 1:1 basis where appropriate site conditions allow. Due to the seasonal limitations and the work needed to grind out stumps and replant new trees, this process can take one to two years. The City of Burlington supports fair and equitable treatment for all residents, so replanting is prioritized based on when trees were removed. The size of tree chosen is standardized, as smaller trees establish and grow faster as compared to larger trees, which may have had more roots cut off during nursery production.  

In woodlands, proactive removals of ash trees have been initiated. Trees which may fall and injure people in back yards, or on maintained city trails and parks are being removed. Protecting the health and safety of residents is a top priority. Trees that are infested but are not within the areas that people generally use, will remain as habitat or wildlife trees within the woodlands.  Trees are left as logs and brush in the woodlands to decompose over time, returning organic material to the environment. This is the regeneration cycle of natural environments; wood removal or chipping with heavy equipment would be even more detrimental to the already impacted ecosystems. While it may appear messy at first, forests respond well to increased light and space, and new growth appears quickly. As woodland removals near completion in 2019, proposals to update the 10-year old Urban Forest Management Plan, and undertake a Woodland Management Plan to help restore our woodlands will be brought to City Council for consideration.

The following parks will have significant ash removals which are expected to complete in the summer of 2018:

• Ward 1: Hidden Valley Park
• Ward 2: Central Park
• Ward 3: Lowville Park
• Ward 4: Nelson Park, Tuck Park
• Ward 5: Sherwood Forest Park
• Ward 6: Ireland Park

We encourage residents to also become stewards of our urban forest which provides so many environmental and ecological benefits, and encourage all to consider planting more trees on their private property, where suitability exists. If there is an ash tree on private property, the property owner should consider hiring a certified arborist to discuss options. Property owners are responsible for managing their own trees on their property.

Does the City of Burlington have any information on natural control of EAB (Emerald Ash Borer)?

The Emerald Ash Borer Action Plan

The Canadian Forest Service is working on a pilot project where they have been releasing non-stinging Parasitic Wasps (Encyrtidae, Eulophidae, Braconidae families) in various locations in Southern Ontario which include Ottawa, London and Newmarket. These wasps are native to Asia where they attack and kill EAB larva. Since EAB has no known predators in North America they are introducing this wasp to help control EAB in the future. This project is still in the early stages of development and no results on any potential impact of the parasitoids on EAB populations are available yet. For more information please refer to the following sites:

Canadian Forestry Service

Biological control of Emerald Ash Borer