British Columbia: Southern Magnolia Bark Rot

Hello, my mother in law's southern magnolia has just bit the dust after 12-15 years of growth, due to some nasty canker on the bark about 18-24" above the ground. We didn't notice it until we whacked out a bunch of salal around the base, revealing a fully girdled trunk.

Any ideas what this might be? We didn't notice any orange or rust coloured spores (canker) but it looks like the results of a canker. Also wondering if it was the result of something physical girdling the tree for a few year with no one noticing? Or perhaps an unhealthy relationship with salal?!?

Secondly, any thoughts on next steps? we have hosta, hellebore and hakonechloa around the base, along with the salal that we'll likely remove altogether. We'll take down the tree but wondering if all this material is safe to keep? Should we avoid another southern magnolia or go with something else - dogwood?

Your comments are appreciated!

 

Yes, there is some torn material as though the tree was damaged mechanically. And the top rim has a chiseled appearance, as though it was gnawed by a beaver.

 

Thanks Ron. I suspect that it was something like the original burlap string or something girdling the tree, then a lot of decay resulting from the weakened bark. I don't think it's beavers or rodents, the cambium beneath the bark is untouched. The trunk is definitely thicker in diameter above the wound.

joe

 

The torn edges at the base was me, by the way!