I have seen a flood plain full of Russian Olive near Billings (latitude 45.8). I have seen it proliferate in Medicine Hat area and Brooks both in Alberta, latitudes about 50.5 and 50.6 respectively, and in Moose Jaw Saskatchewan area about the same latitude. I just received a report that it is a "target" species in the area of Kamloops, BC latitude 50.7 along the Thompson River there.
I am saying again to the Nursery industry, find some alternatives to this bright silver tree that is so striking to customers in a retail lot, and maybe the only species I know that is a medium size and has silver leaves.
I am saying to Toronto area, if you haven't put this on your radar, you better. The cost is enormous to take these out.And the safety hazard due to the thorniness is high for the maintenance of grass or areas around them is almost impossible without special safety equipment. See these video links from Wyoming:
Russian Olive Removal Demonstration on 2/16/08 http://www.mywyoming.org/video/gqgey55cet
Advance the video to the people talking with it to gain their insights
Russian Olive - A Noxious Weed http://www.youtube.com/watch?v=bTv3DW0fyD0
This short video gives some good video images of infestations and a few reasons why it is a Noxious Weed in Wyoming.
I hate to say it, but I guess that sooner than later there will be regulations against Russian Olives in some provinces in Canada. I always say to my friends in the retail garden industry, "Be the leaders. Do what is right with ornamentals that are proven problems. It is good business." So be the leader in this and start to market alternatives to Russian Olive.