I am looking for narrow trees to line my one acre property which are safe for horses. I was interested in Acer rubrum 'columnare' but have learned that it is very poisonous to horses. Does the same go for Acer saccharium 'Newton Sentry'? If not, is it available in the Lower Mainland? Any other suggestions?
Did a search for info, the toxicity problems are confined to Acer rubrum and Acer × freemanii (A. rubrum × A. saccharinum); pure A. saccharinum and other maples are not a problem.
If you choose broad or at least broader trees you won't have to plant so many, and you won't have the tense effect produced by rows of spike-like columnar trees all around.