A couple possible solutions come to mind:
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Permaculture: Plant more guild/insectary plants around the tree and wait for natural predators to arrive, and/or for for the guild plants to enhance the tree's health & resistance to the scale.
Strandard Horticulture: Spray dormant oil.
I don't know how apricots are in your area, but if I had a similar problem I would probably just wait for the predators... apricots are incredibly tough here in Kamloops.