Euonymus Tree Rejuvenation?

(Question)

I live in Barrie, ON. I have a euonymus tree that is not doing well this year at all.

It did have some green leaves and new growth in the spring, but those have since shriveled and fallen off (see photo attached).

There is growth coming off the trunk, but I don’t know whether to cut these suckers off, or leave them. I know the tree likely won’t come back this year, but is there any hope for it at all, or is it done for? What should I do to help it?

Some of the branches at the top still seem supple, but most are very brittle and dry.
At the advice of a local garden shop I did fertilize it in the spring and have been watering it a fair bit, but I was worried about over-watering.

Thank you,
-Sherry McKever-Walsh

 

(Answer)

Thank you for contacting Toronto Master Gardeners. No one wants to be the bearer of bad news but your euonymus tree does look pretty dead. Now there are numerous varieties of euonymus and unfortunately it’s impossible to identify yours from the photo. Regardless, it would be a good idea to try and determine what is causing the tree to die, before you try any treatment.

From the photo it looks like the new growth you mention is quite low down on the trunk. The leaves on this new growth do not appear to resemble those of an euonymus plant. Perhaps your tree was propagated by grafting and the graft union has failed. (Hopefully, you were made aware of this at time of purchase). If not take a good look at the base of the trunk. A graft would be pretty obvious. The rootstock may have become partly or completely separated from the trunk (scion) causing the failure and there may be signs of decay around the join. This would compromise the flow of nutrients from the rootstock to the top growth resulting in dieback, poor growth or death in the top part of the plant. The root system remains alive and sends up suckers. This could well be the case in your situation and its unlikely your tree will come back to its former glory.

You mention that some of the branches are dry and brittle. If you still want to try something then start by pruning out those branches.  (A good way of checking which branches are still alive scrape the surface of the bark and if you see green and it feels slightly damp to the touch there’s life. A dead limb will be brown and hard to scrape). You probably will have to wait until next spring to see if this has any affect.

All euonymus species prefer full sun or light shade and fertile, moist, well-drained soil. They do not tolerate waterlogged soil.  You might want to check that. Presumably you eased off on the watering as you said you were worried about over watering, which can cause leaves to drop off.  Try putting mulch around the base of the tree, without touching the trunk, to increase drainage. By the way forget about fertilizing at this point.

Unfortunately, euonymus is prone to a number of insects and diseases. The most common and serious being scale and caterpillars. Look for small bumps on the branches for scale and for the presence of caterpillars you would see webbing and the caterpillars themselves. Both will cause leaves to drop and serious infestations these critters will completely defoliate the plant. There are also a number of fungal diseases that will cause leaves to drop causing defoliation. Cool wet springs exacerbate the problem. In all these cases keep the ground clean below the tree by raking up and destroying leaves.

Here are some links to articles on how to care for your euonymus:

https://hgic.clemson.edu/factsheet/euonymus-diseases-insect-pests/

https://extension.umd.edu/hgic/euonymus-scale-shrubs

https://www.chicagobotanic.org/plantinfo/euonymus_scale

http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/insects/scale/euonymus-scale.aspx

Good luck with bringing your euonymus tree back to life.