Native Plants

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Thursday - January 22, 2009

From: Flower Mound, TX
Region: Southwest
Topic: Trees
Title: Brown circular ring in trimmed branches of redbud tree
Answered by: Nan Hampton

QUESTION:

I have a redbud tree that was recently trimed back. When looking at the cross section of the branches, I noticed a brown circular ring. Is this a problem and if so what can I do to correct it?

ANSWER:

The dark ring you see is possibly the heartwood beginning to form in the branches of your Cercis canadensis (eastern redbud). If you could see a cross section of the trunk of your tree, you would see that the center of it is a reddish-brown color, the inactive heartwood; whereas, the wood surrounding it, the sapwood, which actively transports water and nutrients (the sap), is yellowish tan. You can read a good discussion on the difference between sapwood and heartwood at Northern Woodlands.org. Twigs and younger branches contain only sapwood; but as the branches grow in diameter, the lighter sapwood is transformed into the darker heartwood towards the center of the branch. The heartwood provides structural support. So, it is possible that the forming heartwood is the dark ring you see in your cut branches. Click here to see the wood of several species of Cercis.

You can read about a variety of damaging agents to the redbud and it is possible that your dark ring is an indication of some fungal disease or insect damage. If your redbud shows other symptoms (e.g., fungal growths on the trunk) that give you concern, it would be a good idea to consult your Denton County Texas AgriLife Extension Service agent and/or a certified arborist who can look at your tree and diagnosis the problem and possible ways to treat it.