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Trees - plant parasites
Expert: Jim Hyland - 10/14/2008
Question
please tell me the plant parasites that grow on a live oak besides mistletoe.
Answer
Mistletoes is about the only true plant parasite on live oak. Spanish moss, Ball moss and lichens are sometimes classified as parasites. Some vines like wisteria can be parasitic if they cover the foliage of a tree.
BALL MOSS
Ball moss is an epiphyte. It is capable of manufacturing its own food from nutrients and moisture taken from the air. Unlike mistletoe, it does not derive its food from the host. Although often associated with plants that are in an advance stage of decline, it is not the cause of the decline. In some areas, the moss becomes so dense, that it possibly is restricting normal bud development.
LICHENS
Lichens are an example of a symbiotic relationship between algae and certain fungi. They are capable of producing their own food. The algae associated with the fungus is a green or blue-green alga. There are three forms of lichens based on growth patterns. Crustose are species that are closely pressed against the surface of the limb or trunk of dead or live trees. Foliose forms are leaf like or prostrate but are also tightly attached to the tree. Fruticose forms are bush like, erect or hanging.
The effect of lichens on a tree are only slightly detrimental. The plants are epiphytes. That is they derive their nutrients from the air and not from the plant on which they are growing. Although they are not parasitized, literature reports suggest that lichens do have a slight negative effect. The main concern is that lichens give a tree an unkept appearance. Presence of lichens also is a good indicator of a thin tree canopy.
SPANISH MOSS
Spanish Moss (plant - Tillandsia usneoides): This long, whisker-like plant growth hangs from trees. It is an epiphyte. It grows on hardwoods and conifers along rivers and creeks in the more humid areas. It is a member of the pineapple family (Bromeliaceae). It has been reported to kill trees where development is extensive. This seldom occurs.
MISTLETOE: PEST OR NUISANCE
Mistletoe is an important part of the holiday season. Branches are frequently hung over the door as part of the celebration. Many a young girl or boy received their first kiss while standing under the mistletoe. Unfortunately that is the only good use for this plant. For the rest of the year homeowners are concerned about how to rid their trees of this pest. Although it is a green plant and manufactures its own food, it is a parasite. Water and nutrients needed by mistletoe for its growth and development are taken from the tree's sap.
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