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.
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.
On the other hand, mistletoe is native to this region and provides food for many songbirds that stay in North Carolina throughout the winter. Appearance of mistletoe is symptomatic of a healthy and diverse ecosystem and should not warrant major concern from homeowners.
How can I control mistletoe?
Mistletoe can be effectively controlled in landscape trees by pruning out infected branches as soon as an infestation appears. Prune out smaller limbs by cutting them off at their point of origin from larger branches. While this can help slow the growth and spread of mistletoe throughout the tree, this method of control may not eradicate it.
Heavy pruning can be effective at controlling mistletoe and improving tree structure if done correctly; however, you should avoid topping as this can be fatal to trees. If you have a landscape tree infested with mistletoe that you wish to preserve, have it assessed by a certified arborist. Any major branch removal should be conducted by a certified arborist. To find a certified arborist in your area, visit the International Society of Arboriculture’s website: www.isa-arbor.com.
If many larger branches are infested and a tree would require extensive pruning of over half its branches to remove all the mistletoe, having the tree removed is likely the better option. Or you can simply leave the tree; it will slowly decline but as it does it will serve as a living birdfeeder. If trees are removed, consider planting more resistant hardwood species of trees like river birch, crape myrtle, and ginkgo, or evergreen tree species like American holly and magnolia.
Use with care
While mistletoe is a decorative addition to your home and provides an excuse to steal a few kisses, you should not eat any part of a mistletoe plant. The berries as well as the foliage are toxic if eaten in large quantities by an adult; however, they will be more toxic for small children and pets.
For gardening and landscape care advice, visit ces.ncsu.edu where you can submit questions via the ‘Ask an Expert’ link, or contact your local Cooperative Extension center by phone: If you live in Pender County, call 910-259-1238; in New Hanover County, call 910-798-7660; in Brunswick County call 910-253-2610.
Sam Marshall is the horticulture agent with the Brunswick County Cooperative Extension of NC State University, College of Agriculture & Life Sciences.