Our magnolia tree is infested with magnolia scale. Can I hire a licensed company to apply a systemic soil drench such as cygon 2E? In the past , I have tried spraying the scales off with a power sprayer, but I cannot effectively reach the top branches. Some branches are dying out. I have seen other magnolia trees in Toronto with magnolia scales. Are the magnolia trees in Toronto commonly dying out?
You are quite correct that this pest is more and more evident in Toronto in recent years. Here is an article from the Toronto Star that describes the invasion of magnolia scale: https://www.thestar.com/life/homes/outdoor_living/2010/07/13/scale_is_sucking_the_life_from_torontos_magnolias.html . The City of Toronto has also produced a fact sheet with advice on identification and control: https://www.toronto.ca/services-payments/water-environment/trees/forest-management/threats-to-trees-insects/
Heavily infested trees can be weakened, or killed by magnolia scale. You seem to have done everything you can, so it may be time to contact a certified professional arborist who can help you to determine the best course of action. To find an arborist in the Toronto area, visit the Ontario branch of the International Society of Arboriculture at https://www.treesaregood.org/. Cygon 2E is a pesticide that Ontario has banned for cosmetic use, as its active ingredient is dimethoate.
Here is an Additional reference for further information: https://www.ontario.ca/environment-and-energy/pesticides-home-lawns-and-gardens