Part of Christmas tradition, this parasitic plant can be deadly to trees
Mistletoe's white berries are a favorite of birds, who help spread the parasitic
plant. (Photos courtesy UCANR)
A tree full of mistletoe may seem like a romantic idea – you could kiss anytime under its branches, not just at Christmas.
But mistletoe could be the kiss of death for its host. This evergreen parasite can slowly kill a tree, sucking out its nutrients and moisture. It’s particularly troublesome for trees stressed by drought or disease.
Over a few Christmases, I watched a beautiful crop of mistletoe slowly take over a neighbor’s birch, one branch at a time, until the tree finally died altogether.
Most of the mistletoe we see in Sacramento is broadleaf mistletoe, Birds – especially cedar waxwings and robins – enjoy the plant’s sticky white berries. It’s the birds that usually spread those berries and resulting mistletoe around.
According to UC Cooperative Extension master gardeners, broadleaf mistletoe (Phoradendron macrophyllum) can infest several different kinds of landscape trees including alder, ash, birch, box elder, cottonwood, locust, silver maple, walnut and zelkova plus some varieties of flowering pear. Modesto ash in particular is very susceptible.
Another species of mistletoe attacks only oak trees. In the Sierra foothills, dwarf mistletoe infests pines, firs and other conifers.
“Broadleaf mistletoe absorbs both water and mineral nutrients from its host trees,” say the master gardeners. “Healthy trees can tolerate a few mistletoe branch infections, but individual branches may be weakened or sometimes killed. Heavily infested trees may be reduced in vigor, stunted, or even killed, especially if they are stressed by other problems such as drought or disease.”
New, young trees, which can be stunted by mistletoe, are at risk from infestations of nearby older trees.
The most effective control? Pruning. Cut out infected branches, particularly while the mistletoe plants are small. If a tree is badly infested, remove the whole tree, say the master gardeners.
Mistletoe grown this big means the tree host is at risk of dying.
Prune it out to get rid of it.
How did a parasitic plant come to inspire Christmas kisses? The tradition can be traced back to ancient Greece.
Historians say mistletoe was a symbol of fertility. Ancient Greeks incorporated mistletoe as part of Saturnalia, a late December celebration of the god Saturn. Couples kissed under mistletoe for luck, a tradition that was also used during marriage ceremonies.
The Romans regarded mistletoe as a symbol of peace, say the historians. Warring factions kissed and made up under a sprig of mistletoe.
In the British Isles, the Druids and ancient Celtics thought mistletoe contained magical powers and used it in ceremonies. That connection got mistletoe banned in many Christian places of worship.
Mistletoe also has a role in Norse legends and other mythology; this little plant got around. Often the legends ended with a kiss under the mistletoe.
Across continents and centuries, the kissing part endured, making mistletoe memorable – more for what it inspires than what it actually does.
For more about mistletoe, check out the UC Cooperative Extension pest notes: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7437.html .
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Dig In: Garden checklist for week of Nov. 27
Before the rain comes later in the week, take advantage of sunny, calm days:
* This may be your last chance this season for the first application of copper fungicide spray to peach and nectarine trees. Leaf curl, which shows up in the spring, is caused by a fungus that winters as spores on the limbs and around the tree in fallen leaves. Sprays are most effective now, but they need a few days of dry weather after application to really “stick.” If you haven’t yet, spray now.
* Rake and compost leaves, but dispose of any diseased plant material. For example, if peach and nectarine trees showed signs of leaf curl this year, clean up under trees and dispose of those leaves instead of composting.
* Make sure storm drains are clear of any debris.
* Give your azaleas, gardenias and camellias a boost with chelated iron.
* Trim chrysanthemums to 6 to 8 inches above the ground after they’re done blooming. Keep potted mums in their containers until next spring. Then, they can be planted in the ground, if desired, or repotted.
* Prune non-flowering trees and shrubs while dormant.
* Plant bulbs for spring bloom. Don’t forget the tulips chilling in the refrigerator. Other suggestions: daffodils, crocuses, hyacinths, anemones and scillas.
* Seed wildflowers including California poppies.
* Also from seed, plant sweet pea, sweet alyssum, bachelor buttons and other spring flowers.
* Plant most trees and shrubs. This gives them plenty of time for root development before spring growth. They also benefit from winter rains.
* Set out cool-weather annuals such as pansies and snapdragons.
* Lettuce, cabbage, broccoli and cool-season greens can be planted now.
* Plant garlic and onions.
* If you decide to use a living Christmas tree this year, keep it outside in a sunny location until Christmas week. This reduces stress on the young tree.
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