Here are this week’s gardening questions and answers, provided by Parker County Master Gardeners. To submit a question, send it to firstname.lastname@example.org. For more information about Parker County Master Gardeners, or to become a member, call 817-598-6096 or visit www.pcmg-texas.org.
Will mistletoe harm my trees?
Mistletoe is a parasitic plant that grows in a wide range of host trees. It is spread by birds that rub the sticky berries off their beaks onto tree limbs or pass them through droppings. Seeds that are spread in February and March may stick long enough to sprout. The plant attaches to the tree by a root-like appendage that sinks into the limb seeking water and nutrients.
Biologists and organic growers alike agree that a mild infestation will not harm an otherwise healthy tree; however, the growth of mistletoe over the years will weaken the branch and may cause it to break. In an unhealthy tree, mistletoe can reduce the growth rate and may eventually kill the tree.
There are hundreds of species of mistletoe. Some are poisonous, while others have therapeutic and environmental value. As a result, it appears frequently throughout history. Celtic tradition quotes it as a remedy for barrenness in animals and an antidote for poison. Europeans used it as a common treatment for epilepsy and nervous disorders. The traditional Christmas kiss under the mistletoe was first seen in Christian tradition in the 16th century.
In North America, the dwarf variety has a densely branching mass that suggests the popular name “witches brooms.” The Navaho call it the “basket on high.” In a recent study, it was discovered that more than 240 species of birds nest in mistletoe. Another study suggests that berry-producing shrubs and trees are actually more prolific when mistletoe is present, and today it is used in cancer treatment.
All things considered, your decision about mistletoe depends largely on your goals and the location of the infested tree. If your property is heavily wooded or you harbor birds and other wildlife, you may choose to let it grow and contribute to biodiversity in your area. If the tree is next to your house or driveway, a weakening limb may become a safety factor that requires removal. If the tree appears to be suffering adversely, you may want to remove the growth in order to improve the tree health.
Mistletoe can be removed by judicious pruning of the limb to remove the entire mistletoe root, which may be up to a foot long.