Mistletoe is often found hanging in homes as a traditional decoration during the holiday season. It was once believed to have magical powers, as well as medicinal properties. Most mistletoes are evergreen, making them more visible and easier to locate after leaves of their deciduous hosts drop in late fall and winter. Although mistletoe is generally associated with winter holidays, this parasitic plant grows year-round and can kill trees.

Oak mistletoe (Phoradendron leucarpum), is the native plant found in the canopies of our trees. As the name suggests, oak mistletoe parasitizes oak trees; however, it can grow on up to 105 tree species including alder, birch, cottonwood, maple, hickory, and elm. Mistletoe forms a drooping yellowish-green, evergreen bush, 2 to 3-feet long, on the branches of a host tree. Mistletoe has crowded, forking branches with 2-inch long oval to lance-shaped, leathery leaves arranged in pairs opposite of each other on the branch. The small flowers are yellower than the leaves and appear in late winter. The flowers give rise to one-seeded white berries that are toxic to humans. However, birds eat the berries and distribute the sticky seeds in their droppings or by wiping their seed-covered beaks against a tree’s bark.

As a hemiparasite, mistletoe contains chlorophyll to make its food, but relies on its hosts for water and nutrients. Once a mistletoe seed germinates, a modified root penetrates the bark of the host tree to form a connection through which water and nutrients pass from host to parasite. Mistletoes are slow-growing but persistent.

Healthy trees can tolerate small mistletoe infestations, but individual branches might be compromised and susceptible to wind or ice breakage. Simply removing mistletoe will provide some protection from spreading. However, if you remove only the mistletoe, it will probably regrow. To effectively control mistletoe, prune the tree one to two feet beyond the point of attachment. If the mistletoe is located on a main limb or trunk, remove the top of the mistletoe and wrap the cut with an opaque plastic to prevent sunlight. Since mistletoe requires light, it will die within a couple of years. It might be necessary to repeat this treatment, especially if the wrapping becomes detached or the mistletoe is not completely killed.  In a tree where many branches would have to be removed to rid it of mistletoe, simply letting nature to take its course is the better option as removing multiple branches is harmful and often fatal to trees.

For more information, contact our office at 706-795-2281 or clh@uga.edu.

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