Question
Hello,
We have found a beautiful Leonard Messil Magnolia.  We happen to reside next to neighbors who have three black walnut trees.  Is the Leonard Messil Magnolia susceptible to black walnut toxicity?  I am aware the Saucer Magnolia is, but need to know about this particular cultivar.  
Thank you.

Answer
As long as you do not plant the magnolia under the drip line of the walnut tree it will be ok. Two things can happen--the walnut tree will shade the walnut and the sap of the walnut could effect the root system of the magnolia. Plant it away from the walnut and you will not have a problem. I see No reason not to plant the magnolia in your yard.