No growth on crown of Emperor Japanese Maple, roots extendIng above soil line

(Question)

Hi:

We’ve had this Japanese Maple for about 5 years now. We planted it where an old silver Maple stood. The stump of the Silver Maple was ground down, but remnants of it likely remain below ground.

Growth on the Japanese Maple has always been slow and each year I try to cover the root system with top soil. At the end of last year, I noticed some dying branches near the top of the tree. This year as you can hopefully see from the photo, leaves are only coming out near the base of the tree. What would you suggest I do to bring it back to health? Thanks so much.

(Answer)

Thank-you for contacting Toronto Master Gardeners with your question.

Unfortunately, your photo did not come through with your question. Because branch or crown die back on Japanese maples is quite common, I will give you some initial responses based on the usual situation. If these do not really address your question adequately, please feel free to try re-sending your photo and question. The link below is for a previous Toronto Master Gardeners’ answer to a similar question:

https://www.torontomastergardeners.ca/askagardener/japanese-maple-bloodgood-tree/

The following answer gives information on a more dire case of die back of crown:

https://www.torontomastergardeners.ca/wp-admin/post.php?post=20773&action=edit

Japanese maples are actually fairly sturdy plants but they do have a few key requirements. They need to be watered well in dry periods, but equally, they do not tolerate wet feet or poor drainage. You mention that in attempting to provide a good situation for your tree you have been covering its roots with topsoil each year. In fact, this could be causing your problem. Maples have shallow root systems, and prefer having roots near (or sometimes on) the soil surface. If the drainage in the soil around your old silver maple is not great, you may be contributing to a wet root problem by adding soil to the root area. Adding a layer of mulch to the root area (keeping it 4 – 5 inches away from the trunk) will help the soil around your tree from drying out while not contributing to  water-logging. It also offers some protection to the roots in the winter.

Since your maple began to experience some dying back last summer, it may also have been particularly susceptible to further dying back related to winter weather (even though last winter was not particularly severe).

The first thing you need to do is to prune off the dead branches.  You will be trying to prune back until you reach live wood. Once you have done this, assuming the tree has enough foliage left to survive, you will need to watch vigilantly for any disease or insect infestations attacking the weakened tree. You will also need to continue pruning for health and shape. The article below gives some good information about this:

https://ipm.missouri.edu/meg/2008/3/Caring-for-Freeze-Damaged-Japanese-Maples/

This article gives some good general information about growing Japanese maples in Ontario:

https://landscapeontario.com/japanese-maples

I hope you are able to save your Japanese maple. They are such lovely trees!

May 4, 2021