What to Know about Mistletoe

February 20, 2024

Carolyn Dawson
Area Extension Forestry Agent
Anderson, Cherokee, Greenville, Oconee, Pickens, & Spartanburg Counties

Now that deep winter is upon us, and the trees are bare of leaves, it is extremely easy to see the round, green balls of leaves scattered throughout the tree canopies. This is mistletoe.

“Mistletoe “roots” may extend up to a foot on either side of the point of attachment. Bob Polomski, ©2018, Clemson Extension”

Is it harmful to trees? Well, kind of. It is considered a parasite, a hemiparasite, to be exact. A hemiparasite makes some of its own food through photosynthesis but takes water and most of its nutrients from the host tree. American or Oak Mistletoe (Phoradendron serotinum) is commonly found on deciduous trees such as pecans, oaks, elms, hackberries, maples, and wild cherries. In the fall, it produces white berries that contain toxic chemicals poisonous to people and domestic animals.

Where did it come from? Birds are the most common culprit. They consume the sticky, white berries, and then transport the seeds to other trees where the seeds can germinate and begin their parasitic journey.

Mistletoe uses specialized roots called haustoria, which penetrate the host tree’s bark, allowing them to embed themselves in the vascular tissue. Through this connection, mistletoe siphons off nutrients from its host, sustaining itself.

What should you do if you have mistletoe? The primary method of management involves pruning out the infected branches. Prune the affected branch at least 18 inches beyond the point of attachment. Simply removing the mistletoe plant, without removal of the infected branch, will provide some protection from spreading. However, if you remove only the mistletoe, it will probably regrow.

For more extensive infestations higher in the tree, it’s advisable to enlist the services of a professional Certified Arborist. For some older, larger, heavily infested trees, it may not be feasible to remove such large portions of the canopy, and best just to let the tree live out its natural life or have it removed.

If you’d like to learn more about tree insects, diseases, and issues, or perhaps invite Carolyn Dawson, Clemson Extension Forestry Agent, to speak at your event, please contact her at dawson4@clemson.edu.