Well, the European mistletoe does / did exist in Canada: European mistletoe (Viscum album subsp. album) in Canada (abstract) | Canadian Forest Service Publications | Natural Resources Canada And I think a naturally diverse forest (species-wise, age-wise, health-wise) would be another method of preventing rapid mistletoe spread.
In the early 196os, Woodward's Department Store in New Westminster (and perhaps other locations) used to sell live mistletoe in the weeks before Christmas. I don't know what species it was or if it could still produce seeds after being picked but the shocking thing to me was finding out, years later, that it is poisonous and was being sold in the grocery department - in the produce section no less!
