Wednesday, May 4, 2016


I've been fairly disturbed recently to notice some cracks in the bark of a maple and some redbuds in my garden...

Here's the red maple (Acer rubrum) showing cracked bark and some new growth emerging from the trunk below the crack. This tree is probably about 15-20 feet tall, with a bare trunk for 5-6 feet off the ground. When we had a landscaper install it a few years ago, it was already pretty much this height with a very slender, upright growth habit. In other words, the 'canopy' (such as it is) offers little-to-no shade protection for the trunk in a full-sun setting.

This redbud - also in full sun - has a vertical crack extending for several feet along its trunk almost to the soil line.

Yet another full sun redbud (Cercis canadensis) with a crack extending almost the entire length of the trunk. I don't know whether these cracks will kill or hurt the trees - whether they are a symptom of poor health or whether they might cause the trees' demise by providing entry for diseases and insects. Or perhaps the trees will be able to heal themselves and seal the cracks on their own with new bark? I do suspect that sun scald might be part of the problem, so if the trees do survive, I plan on wrapping the trunks with some sort of protective tree paper next winter to protect the bark.

Here's a volunteer redbud looking extremely healthy. It seems to me this little guy has a much bushier growth habit than the redbuds we had installed from a tree nursery. As I understand it (and from what I observe), redbuds often grow naturally in a forest understory or on the edge of a woodland. In those situations, perhaps redbuds would have a lanky, upright growth habit. But it seems to me that in the open, redbuds - like this volunteer - would have a bushier growth habit so that that the leaves could protect the bark of the trunk, at least during the summertime. (This theory sort of falls apart for wintertime protection, since the tree will be bare and the bark probably unprotected regardless of the growth habit of the branches...)

Have you experienced bark cracks due to sunscald or other causes (such as frost crack) on maples, redbuds or other trees? Were you able to protect your trees from such issues with tree wrap or other methods?



  1. Lost a very expensive live oak to Sun scald about 5 years ago. Colder than typical winter got my tree and two others planted by the same landscaper at a different home. Oak struggled for a year sending out new growth below and away from the crack, but to no avail. Replaced with a native red maple and a Trident maple. I have tree wrap in my arsenal, but our winters the last few years have not been as extreme. (Virginia zone 7b). Hoping your trees manage to hang on.

    1. Ugh. That's awful.

      Sorry to hear about your live oak loss. Hope the replacement maples have performed well in your garden.

      Interestingly, all of these trees were in fact planted by a landscaper, whereas I have not encountered this problem on any of the trees or shrubs that I planted myself.

      Perhaps part of the issue is the fact that the landscaper planted tall trees with narrow canopies where the leaves cannot shade the trunk? In addition, I suspect that tall-narrow growth pattern comes from a nursery that grew the trees close together in rows out in the field where one tree was shaded and protected by lots of neighbors. When the trees were dug and transplanted (because these were all balled and burlapped) and placed in an open, sunny situation, suddenly their trunks were exposed in a way they had not been before and the trees have struggled to cope with the sudden change.

      Another interesting point is that the cracks occurred after a relatively mild winter. The trees have been in the ground a few years, but I don't recall seeing any major cracks after harsher winters in previous years

      Finally, it could also have something to do with my soil (heavy clay) and the interaction between that soil and the balled-and-burlapped root ball. (I'm not a fan of the B&B method. I think the tree has problems growing out of that root ball and that it's very difficult to get enough roots to support a large tree. I think one usually gets much better results with container-grown plants -- though of course that means starting with a much smaller tree. Still, I think younger container-grown plants often have faster growth rates than the B&B trees, so they can catch up (or close to it) in a few years to their older, taller B&B counterparts. Just my 3 cents.

  2. Sounds like sun scald to me. From what I understand, the best treatment is a little coddling to promote growth - either top dressing with compost or some spring fertilizer.

    1. Thanks for the suggestion, Jason.

      I may try some compost and then a bit of mulch. I haven't mulched around these trees much in the past couple of years...


Need to add an image? Use this code [img]IMAGE-URL-HERE[/img]