Definition, Bark Split "Freezing temperatures are especially dangerous to unprotected branches and main stems, causing the bark to split and separate from the body of the the stem. In severe cases, a limb will become completely girdled and everything above that point will die; in cases of moderate damage the bark splits and rolls back but not to the point of girdling the branch. Such injury is deceptive in that affected branches may not die until the following Spring or Summer, going unnoticed in the meantime while hidden by foliage. Sometimes freezing conditions will only split the bark without causing it to separate from the core. These wounds often callous over and allow the plant to function normally, but until the cracks heal they provide easy entry to fungus infections. Grafting wax painted onto these cracks will aid in their healing process and prevent diseases from entering." Here is a link that might be useful: Photo #8, Bark Split Rhododendron

i am in adrian mi ... prime planting time in MI ... is ground thaw in late march ... minimum 6 to 8 weeks before leaf out ... OR!!!!! and late sept thru about now ... so this is your window of opportunity ... for next year ... gee tree farm is just north of jackson MI ... off I-94 ... with a 15 acre arboretum .. and hundreds of acres of trees... it would be a brilliant trip ... NOW ... call ahead... ask for cary ... and explain what you are looking for .. and ask if their field trees are still holding leaves.. and if you could mark some for next summer .. it might require a deposit ... and that is up to them ..... [i would have you mention my name.. but i dont know if it would be a positive.. lol ] .. make an appointment for someone with a golf cart to whisk you around the property .... you might be able to find some out your way also ... google tree farms grand rapids ... the larger the tree.. the more roots you cut off to transplant ... no tree will perform to expectations until it regrows its root mass .. so a larger tree.. will take years longer to recover ... smaller will get 'established' faster .. and can outgrow a larger specimen.. inside 5 years .. not to mention.. if you are doing this yourselves.. how to move.. transport ... carry.. and plant.. a humongous ball and burlap.. sans heavy machinery ... i have tried that.. nearly ended up needing surgery .. not cool ... my dichotomy.. is based on you doing it.. versus big checkbook professional installation ... its not that it cant be done... its what can be done in your budget .... i am impressed you are so far ahead of the curve... usually peeps want instant gratification.. rather than planning a year out ... should you be thinking of doing this yourself.. read.. digest. and commit to memory.. EVERYTHING at the link ... doing it the right way... really matters .... ken Here is a link that might be useful: link

Thanks, gardengal. I think you may be right that the tree was deeply planted. We've never seen a skirt of larger, exposed roots. I have tried to pull dirt and mulch away from the trunk, but it's really tight with roots and almost impossible to do. If you look closely, you can almost see the line on the trunk where the mulch used to be, a couple of inches above where it is now. I don't think I can get the dirt/mulch level any lower, really. Overall, the mulched area is probably only a few inches higher than the surrounding lawn. On your advice, today I added a little compost and a light layer of mulch over those exposed feeder roots. I may post again when I get the soil test results. Thanks again!

I probably would NEVER go to that nursery again... It doesn't look like a sweet gum at all... but any person in the tree biz would just take a leaf and crunch it up and smell it...if it were a gum it would be obvious by it's gum smell...I think those folks were either pulling your leg or just idiots. At any rate i wouldn't go back for either of those two reasons.. David