Mistletoe can be a lovely holiday sight when hung on a door sill, but is an unwanted intruder when found in trees outside.
“Mistleweed is a hemiparasite—it’s a semi-parasitic plant,” says Allison Watkins, AgriLife Extension gardener in Tom Green County at Texas A&M University. “It makes its nutrients from photosynthesis, but the roots grow into the host tree, absorbing water and minerals from the sap”
In other words, you probably don’t want to see mistletoe growing on your favorite shade tree or precious ornamental plant. However, mistletoe can live as long as the tree it lives on. So, some mistletoe alive today may still be around 100 years from now.
One species of mistletoe that is commonly used as decorations during the holidays is in the family. PhoradendronIt aptly means “thief of the tree” in Greek.
Mistletoe has been used in various cultures throughout history for a variety of things, including preventing demons from entering through doorways and protecting babies from being stolen from their cradles by fairies at night.
Although mistletoe is called the kissing plant, its name may have originated from Old English words meaning twig and dung. How will that get you in the romantic holiday spirit?
Mistletoe 101: Don’t Eat It
Watkins says mistletoe causes tree stress and can make the tree more susceptible to diseases and insects. While unlikely to kill a healthy tree, it can cause limb death. It can be particularly difficult on a tree during a drought.
Mistletoe is easily spread by birds eating the berries and then spreading the seed from branch to branch and from tree to tree with their droppings. The seeds are extremely sticky and can also hitchhike on their feet and beaks.
Some mistletoe species can also launch their own seeds at around 60 mph when the fruit bursts like an overfilled water balloon.
Some mistletoe is poisonous, so it’s always wise to be careful when handling the plant. Different parts of the plant and different species have varying levels of toxicity. While birds and wildlife eat the fruit, it’s not something you want your family members, including pets, to eat.
Mistletoe is most easily noticed during the winter, when most of the host trees lose their leaves to reveal clumps of evergreen mistletoe. The spherical shape can be several feet wide.
Because birds like to perch on the tops of tall trees, mistletoe is most commonly found on mature trees near the top. A tree branch can be grown where the plant attaches itself.
Mistletoe plays an important 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 species of butterflies and moths that rely solely on mistletoe species as host plants for their caterpillars.
“Birds aren’t the only animals that eat mistletoe; squirrels also eat the fruit, and deer and porcupines eat the plant itself, especially if other foods are scarce,” says Maureen Frank, an AgriLife Extension wildlife specialist at Uvalde.
Frank says many animals nest in clumps of mistletoe, especially when the plant causes the host tree to form witch’s brooms, which are dense masses of crooked branches. Mistletoe and related witches’ brooms are used as shelters by a variety of birds, from tree squirrels, flying squirrels and small nightingales to birds of prey such as Cooper’s hawks.
Mistletoe damage to trees can also provide a home for cavity-nesting species of birds, bats, insects, and small mammals.
“Even if you remove the mistletoe from a tree, the root-like structure remains embedded in the tree, meaning it will regrow,” says Watkins.
The only way to eradicate mistletoe from the tree is to prune off the branch it is on. If you think your tree is plagued with parasites, remember that mistletoe takes two to three years to mature; so the sooner you remove the infected branch, the better you will reduce the spread. And the smaller the branch that needs to be removed, the less stress on the tree.
“Most well-maintained plots may have mistletoe here or there, but that’s probably nothing to worry too much about,” says Watkins.
The stress from over-pruning can be more harmful than the mistletoe itself, she says. Watkins says to keep these tips in mind if you decide to prune:
Light pruning can be done any time of the year, but more substantial pruning is best done during the winter months when the tree is dormant.
- Do not prune more than a third of the shade of a tree.
- Dead branches can be removed at any time.
- Oak trees should not be pruned from February to June to prevent the spread of oak wilt. December and January are ideal times to prune oaks.
- Paint the cutouts to protect the tree.
Source: Texas A&M University