News release

City’s 2022 Aerial Spray Program Completed

Environment | June 8, 2022

Today, the City of Mississauga completed the final application for the 2022 Aerial Spray Program, which began on Saturday, May 28. Over the last 12 days, the City conducted two applications of the spray as planned which targeted Lymantria dispar dispar (LDD), formerly known as “gypsy moth,” in affected city neighbourhoods.

The spray covered both private and public land in Wards 1, 2, 3, 5, 6, 7, 8, 9, 10 and 11 with 16 City neighbourhoods and roughly 2,100 hectares (5,189 acres) being sprayed. Zimmer Air Services Inc. was contracted to conduct the spray on behalf of the City.

“Weather is a determining factor in the success of an aerial spray program. We were fortunate the weather co-operated and the spray occurred at the right time – just as the LDD caterpillars were starting to feed,” said Paul Tripodo, Project Lead, Aerial Spray at the City of Mississauga. “Next steps for our team include active monitoring in areas that have been sprayed to determine the extent of defoliation experienced by the tree canopy in these areas. We’ll be collecting and analyzing the data over the summer months and by fall we will have a good understanding of the overall success and effectiveness of the spray. Given the favourable conditions during the application period, we’re expecting a positive outcome.”

Neighbourhoods Sprayed
Central Erin Mills
Clarkson-Lorne Park
Cooksville West
Creditview
East Credit
Erindale
Erin Mills
Gordon Woods
Meadowvale Village
Mineola
Rathwood
Sheridan
South Common
Streetsville
Southdown
University of Toronto Mississauga (UTM)

Parks and Woodlands Sprayed
(outside of the listed neighbourhoods)
Britannia Woods Community Forest
Dr. Martin L. Dobkin Community Park
Eden Woods
Hyde’s Mill Hollow
Jaycee Park
Marco Muzzo Sr. Memorial Park
Meadowvale Conservation Area
Paul Coffey Park
Pinecliff Park
Riverview Park
Riverwood
Sparling Woods
Staghorn Woods
Windrush Woods

Over the last few years, the City has been able to control LDD caterpillar populations using other Integrated Pest Management (IPM) measures, such as tree banding, tree injections, ground spraying and egg scraping. However, in certain areas of the city, these methods alone were not enough to address the scale of the current outbreak.

As LDD caterpillars grow, they feed on leaves – defoliating trees, making them weak, more susceptible to diseases and extreme weather. If left untreated, LDD could spread to other areas throughout Mississauga and threaten more of our native forests, parks and neighbourhoods.

Tripodo explained, “LDD is an invasive species that is well established in Mississauga and will never be fully eradicated. An aerial spray is one tool we have to help prevent impacts on our urban forest from the devastating defoliation that can come with an LDD outbreak. There are a number of additional Integrated Pest Management (IPM) practices available to the city and residents to help keep our urban forest healthy and reduce local LDD populations across the city.”

Over the next few weeks, the City’s Forestry staff will work with BioForest to conduct surveys of leaf defoliation on City property trees. In the fall, egg mass inspections will begin to determine next year’s LDD population.

“We have seen positive results from our previous aerial spray treatments and we are expecting the same for our 2022 spray. Collectively as a City we’re working hard to protect and preserve our tree canopy as well as our naturalized areas, woodlands and forests from both invasive pests and plants,” said Stefan Szczepanski, Acting Director, Parks, Forestry and Environment. “I am proud of the hard work that our Forestry team has completed to ensure this year’s aerial spray program was thoughtfully planned and seamlessly executed. I also want to thank the residents living in the spray zones for their patience and support in working with us to protect Mississauga’s trees.”

The 2022 aerial spray program is part of the City’s Invasive Species Management Plan and Implementation Strategy, which responds to the threat of invasive species. The plan and strategy provide a phased, city-wide approach to managing invasive species like LDD, Emerald Ash Borer, Garlic Mustard, Wild Parsnip, Dog-strangling Vine and Giant Hogweed.

Prior to the spray, the City focused its efforts on areas in Mississauga that had higher populations of LDD egg masses. Three strategies were implemented:

Egg Mass Scrapings: scraping egg masses off infested trees.
Tree Injections: injecting trees with TreeAzin® a botanical insecticide.
Ground Sprays: Heavily infected trees were sprayed from the ground using a controlled mechanism such as a pressurized hand-held hydraulic sprayer.

In an effort to contribute to the success of the Integrated Pest Management program for LDD residents are being asked to monitor trees on their property for signs of LDD and help by: