Mistletoe: Pros and cons of keeping and removing the kissing plant

Mistletoe may be a welcome holiday sight when hung over a doorway if a loved one is near. Still, it can be an unwelcome intruder when found in trees, according to Texas A&M AgriLife Extension Service Horticulturist Allison Watkins.

“Mistletoe is a hemiparasite – a semi-parasitic plant,” said Watkins. “It makes its food from photosynthesis, but the roots grow into the host tree, sucking water and minerals out from the sap.”

In other words, one would likely not want to see mistletoe growing on their favorite shade tree or prized ornamental. However, mistletoe can survive as long as the tree it inhabits. So, some mistletoe alive today may still be around in 100 years.

One type of mistletoe commonly used as decoration over the holidays is in the family Phoradendron, which appropriately translates to ‘thief of the tree’ in Greek. Mistletoe has been used across various cultures throughout history for everything from warding off demons from entering a doorway to protecting babies from fairies stealing them from their cribs in the night.

Although mistletoe is called the kissing plant, its name may have originated from the Old English words for ‘twig’ and ‘dung.’ How romantic is that?

The issues with mistletoe

“Mistletoe causes tree stress and can make a tree more susceptible to diseases and insects,” Watkins said. “Although unlikely to kill a healthy tree, it can cause limbs to die, and it can be especially hard on a tree during drought.”

Mistletoe spreads easily. This occurs when birds eat the plant’s berries and then spread the seed from limb to limb and tree to tree through their feces or from their feet and beaks. The seeds are exceptionally sticky.

Certain species of mistletoe can also shoot out their own seeds at speeds of around 60 miles per hour when the berries burst like overfilled water balloons.

Some mistletoe is poisonous, so it is always wise to use care when handling the plant. Different species and parts of the plant have varying levels of toxicity. While birds and wildlife eat the berries, it isn’t something humans or pets should ingest.

How to identify mistletoe in nature

Mistletoe is most easily spotted in winter when many of the host trees lose their leaves, revealing clusters of the evergreen mistletoe. The spherical shape can be up to several feet across.

Since birds like to perch in the tops of high trees, mistletoe is most often found in mature trees near the crown. A tree branch may be enlarged where the plant has attached itself.

Forests, pollinators and woodland creatures

Mistletoe plays a key role in many woodland and range ecosystems. For example, its white flowers provide nectar and pollen for native bees and honeybees. There are also several types of butterflies and moths relying solely on mistletoe species as host plants for their caterpillars.

“Birds aren’t the only animals munching on mistletoe. Squirrels will also eat the berries. Deer and porcupines will eat the plant itself, especially if other food is scarce,” said Dr. Maureen Frank, AgriLife Extension wildlife specialist.

“Many animals nest in clumps of mistletoe, especially when the plant causes its host tree to form witches’ brooms, which are dense masses of distorted branches,” Frank said. “Mistletoe and the corresponding witches’ brooms are used for shelter by tree squirrels, flying squirrels and a variety of birds, from tiny chickadees to Cooper’s hawks.”

The damage done to trees by mistletoe can also provide homes for cavity-nesting species of birds, bats, insects and small mammals.

Removing mistletoe 

“Even if mistletoe is removed from a tree, the root-like structure remains embedded in the tree, meaning it will grow back,” Watkins said.

Although no herbicide exists to kill mistletoe without harming the tree, the plant growth regulator, Florel Fruit Eliminator, is registered in the U.S. to control the growth of mistletoe on deciduous trees, according to Watkins.

The only way to eliminate mistletoe from a tree is to prune the branch it is on. If a tree becomes overwhelmed with the parasite, it is important to keep in mind mistletoe takes two to three years to mature. Therefore, the sooner the infected branch can be removed, the better. Additionally, the smaller branch must also be removed, to eliminate stress on the tree.

“In most well-maintained landscapes, there may be mistletoe here or there, but it’s probably not something to worry about too much,” Watkins said.

In fact, she noted stress from over pruning could be more damaging than the mistletoe itself. When deciding to prune, Watkins encouraged individuals to keep a few things in mind.

“Light pruning can be done any time of the year, but more significant pruning is best done in the winter when the tree is dormant. Prune no more than one-third of a tree’s canopy. Dead branches can be removed at any time, and paint the cuts to protect the tree,” she said.

Susan Himes is an agricultural communications specialist at Texas A&M AgriLife Extension Service and can be reached at susan.himes@ag.tamu.edu. This article was published in the Texas A&M AgriLife e-newsletter on Dec. 12.