Mistletoe: Friend Or Foe
by Dr. Robert Black, Consumer Horticultural Specialist

Mistletoe has been used as a Yuletide decoration for centuries. The soft woody plant, with its dark green, oval foliage and white berries, symbolizes peace and love. The Norse belief may have been the origin of this symbolism as it was said that men who met in battle under mistletoe would stop their fighting, kiss and make-up. The tradition of kissing under the mistletoe may have also originated from the Druids who considered the mistletoe sacred. They believed that it held magical virtue and was a remedy for evil. The priests would cut pieces of the oak tree on which the mistletoe grew and offer them along with two white bulls as a sacrifice to pagan gods. Twigs with berries were hung above doors to indicate that past grievance and hatreds were forgiven and it was used in amulets, bracelets and rings to ward off evil and protect against witchcraft and poisoning.

These customs and beliefs have carried over to its use at Christmas time to encourage passion by way of kissing. Hanging up the white berries was a subtle challenge to kiss the suspecting or unsuspecting individual who stood beneath it.

Mistletoe is not like typical plants which obtain support, water and nutrients from the soil in which they grow. Mistletoe is a parasite which lives in the tops of trees. It sends out roots which penetrate the bark and enter the water and nutrient conducting tissue of a tree. After a young plant is established it grows very quickly and lives about ten years, after which it usually dies from mechanical breakage or excessive shade. Eventually the tree is weakened and will decline in health as it is robbed of its nutrition by the clinging mistletoe.

Mistletoe is very difficult to control because a portion of it grows into the tree's tissue. Breaking away the mistletoe is ineffective as it will redevelop at the point of removal and produce another clump. The most successful method of control is to remove a chip of wood at the point of attachment from the host limb. If mistletoe is on a small limb, the entire limb should be pruned about one foot below the point where the mistletoe attaches.

Recently, a plant growth regulator (ethephon) was found to be an environmentally safe method of control for mistletoe. When sprayed on intact mistletoe clusters, it can cause complete removal of the aerial parts thus preventing plant stress and reducing the possibility of continued infection from this parasite.

Today, mistletoe remains a desirable decoration of the holiday season. Most people think of its attractive white berries and evergreen foliage in this decorating context and are surprised to hear that it is harmful to trees. The plant also has poisonous properties and should be kept out of the reach of small children who may be tempted to eat the berries.