Master Gardener: Mistletoe considered potentially harmful addition to landscape

Published: Thursday, December 5, 2013 at 16:30 PM.

Mistletoe is a common sight this time of year in deciduous trees throughout coastal North Carolina. A parasite of many hardwood trees, mistletoe can also be blamed for the increase in stolen kisses from December through the first of January. While it has had many uses throughout history, this evergreen plant is usually considered to be an unsightly, unwanted, and potentially harmful addition to the landscape. That being said, there are a few factors to consider before deciding whether this is a friend or foe to your landscape trees.

Understanding mistletoe

Mistletoe plants are small evergreen shrubs that persist in trees throughout the year. They can be either male, producing pollen, or female, producing berries. The white berries of the female plants are a favorite food for many songbirds, which feed upon the sticky pulp. Living seeds are excreted and adhere tightly to the branches of trees. Because of the attractiveness of the berries, songbirds often spend a good deal of time in the tree and heavy infestations of mistletoe in one tree are common. After seeds germinate, rootlike structures known as haustoria grow under the bark throughout the branch of the tree.

Mistletoe is parasitic, which means it depends on a living host for the majority of its nutrients. It can take several years for mistletoe to fully mature, so early detection of this plant is difficult. Mature plants can be up to 3’ in diameter and often have a distinctive globular shape. Plants are evergreen, which makes them very easy to spot once deciduous trees have shed their leaves. Look for mistletoe in water oak and red maple trees, the most common hosts of mistletoe in our region.

Is it harmful?

Parasites by nature always cause some harm to their host. In this case, mistletoe steals nutrients and water from their host plant. The answer to the question of whether mistletoe is harmful to trees depends upon the severity of infestation. A small infestation  is often not detrimental to a tree, although individually infested branches may be weakened or die. If a tree is heavily infested with mistletoe, the overall health and vigor may decline and growth may be stunted. Total death is a possibility, especially if trees are stressed by other conditions such as drought, insect, or disease damage.

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