Phoradendron tomentosum

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Phoradendron tomentosum
Phoradendron tomentosum (40817140894).jpg
Phoradendron tomentosum growing on Quercus garryana in Berry Point, CA
Status TNC G5.svg
Secure  (NatureServe)
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Santalales
Family: Santalaceae
Genus: Phoradendron
Species:
P. tomentosum
Binomial name
Phoradendron tomentosum

Phoradendron tomentosum, the leafy mistletoe , hairy mistletoe or Christmas mistletoe, is a plant parasite. It is characterized by its larger leaves and smaller berries than dwarf mistletoe. Leafy mistletoe seldom kill but they do rob their hosts of moisture and some minerals, causing stress during drought and reducing crop productions on fruit and nut trees. [1] Leafy mistletoe has the ability to photosynthesize on its own but it relies on other plants in order to obtain its nutrients. It attaches itself to a tree and then grows haustoria, [2] in order to get the food and water it needs.

Mistletoe

Mistletoe is the English common name for most obligate hemiparasitic plants in the order Santalales. They are attached to their host tree or shrub by a structure called the haustorium, through which they extract water and nutrients from the host plant. Their parasitic lifestyle has led to some dramatic changes in their metabolism.

Contents

Host and symptoms

Symptoms can include dieback, swelling, formations of witches’ broom and weakened branches. [3] Leafy mistletoe can occur on several hundred host species. [3] These include hardwood trees. Signs are green leafy green stems, and berries.

Honey mesquite (Prosopis glandulosa) with Phoradendron tomentosum in Hood County, Texas P145 Honey mesquite (Prosopis glandulosa) with mistletoe (Phoradendron tomentosum) (15321664643).jpg
Honey mesquite ( Prosopis glandulosa ) with Phoradendron tomentosum in Hood County, Texas

Disease cycle

Birds are the primary disease vector in the dispersal of the plant parasite leafy mistletoe. [4] Birds consume the seeds from the fruit of P. tomentosum, also called drupes, and excrete or regurgitate the seeds onto the branches of which the birds perch. The most important birds for effective dispersal include cedar waxwings, euphonias, silky flycatcher, bluebirds, thrushes, robins, and solitaires. [5] The seeds germinate within the tree for several years, eventually producing a haustorium, a root-like structure, that penetrates the host plant and extracts water and minerals from the infected tree or plant. Phoradendron is a hemiparasite, meaning that it produces its own chlorophyll, but relies on the host plant to provide essential elements for growth and survival. [6] Stems, flowers, and fruits also grow from the seed following germination with fruits being produced several years after infection. [5]

Haustorium rootlike structure or a structure that grows into or around another structure to absorb water or nutrients

In botany and mycology, a haustorium is a rootlike structure or a structure that grows into or around another structure to absorb water or nutrients. In botany, this may refer to a cotyledon, or to the root of a parasitic plant that penetrates the host's tissue and draws nutrients from it. In mycology, it refers to the appendage or portion of a parasitic fungus, which performs a similar function. Microscopic haustoria penetrate the host plant's cell wall and siphon nutrients from the space between the cell wall and plasma membrane but do not penetrate the membrane itself. Larger haustoria do this at the tissue level.

Environment

Leafy mistletoe parasitizes a broad range of trees common in amenity and natural landscapes in the United States and the Americas, where winter temperatures are consistently warmer. As are all plants, Phoradendron is subject to death at extremely low temperatures. [7]

Management

Phoradendron tomentosum can adversely affect trees growing in urban environments as well as in forests. [6] Although mistletoe is photosynthetic, it is an obligate, semi parasitic evergreen plant that infects host plants to derive support, water, and essential elements. They are considered a nuisance in urban environments because of their appearance in deciduous trees during winter. When colonization is extensive in individual trees, mistletoe can adversely affect tree health causing a decline and death.

Phoradendron tomentosum primarily infects broad-leaved tree species such as hackberry, mesquite oak, and elm in USDA zone 6 and warmer in the United States. It also commonly infects cherry, walnut, beech, and other tree species. Although some mistletoe species show host specialization, new sites, and new host species have been reported for broadleaf mistletoe. Improving control methods for mistletoe in urban forests is important as a result of the particular interactions of different tree species in varied environments.

Operations include regenerating with a non-host tree, thinning trees to improve vigor and tolerance of the infestation, and sanitation by removing infected trees or branches or removing aerial shoots. Pruning infected branches is often sufficient; where the loss of infected branches cannot be accepted, the aerial shoots can be just knocked off. Mistletoe can be removed from the tree by pruning out the mistletoe shoots at the branch surface. Although the mistletoe might quickly resprout, some benefit is derived by annual mistletoe removal because it reduces seed production and spread of mistletoe within and among trees. Removing the shoots does not eliminate the mistletoe infection but does reduce its reproduction and damage. Shoots will reappear after several years. Covering infected branches with tarpaper or creosote has not proven either attractive or effective. These treatments work by prohibiting photosynthesis of the haustorium by opaque coverings. Perhaps the best way for discouraging additional bird-dispersal of mistletoe seeds is with branch pruning or shoot removal (since it is often the mistletoe fruits that initially attract the birds). Given the modest damage and slow rate of increase of these mistletoes, these methods are usually sufficient. [5]

After seeds germinate, they produce a haustorium or root-like structures that penetrate the host to extract water and minerals. This endophytic portion results in a challenging control problem because treatments must kill the outer ectophytic portion of the plant as well as the endophytic portion without damaging the host.

Importance

Although the Phoradendron mistletoes that infect conifers are widely distributed in the Western United States and in Mexico on a number of common and valuable hosts, their importance is mostly on a local basis and for special uses. In the United States, Phoradendron are most important in California on incense cedar and true fir in certain areas and important broadly across the Southwest (California to Texas) on junipers. [5]

Extensive infections and mortality are uncommon in ashes. However, infections occur typically in open-grown trees. This true mistletoe is used as greenery in Christmas decorations. [8]

Many species of hardwood trees are affected by mistletoe, but oaks and hickories are most commonly attacked. The impact of infestation is not normally severe, but the parasite may lower individual branch vigor. Where infestations are severe, tree decline may progress to the point where insect and fungus pests combine to kill trees. [9]

Injury caused by dwarf mistletoe is manifested in a variety of ways: reduction in tree growth, distortion of growth, reduction in wood quality, predisposition of trees to secondary attack, and reduction in seed yield. [10]

Related Research Articles

<i>Arceuthobium</i> genus of plants

The genus Arceuthobium, commonly called dwarf mistletoes, is a genus of 26 species of parasitic plants that parasitize members of Pinaceae and Cupressaceae in North America, Central America, Asia, Europe, and Africa. Of the 42 species formerly recognized, 39 and 21 are endemic to North America and the United States, respectively. They all have very reduced shoots and leaves with the bulk of the plant living under the host's bark. Recently the number of species within the genus has been reduced to 26 as a result of more detailed genetic analysis.

<i>Phytophthora cinnamomi</i> species of fungus

Phytophthora cinnamomi is a soil-borne water mould that produces an infection which causes a condition in plants called "root rot" or "dieback". The plant pathogen is one of the world's most invasive species and is present in over 70 countries around the world.

<i>Striga</i> A genus of flowering plants belonging to the broomrape family

Striga, commonly known as Witchweed, is a genus of parasitic plants that occur naturally in parts of Africa, Asia, and Australia. It is in the family Orobanchaceae. Some species are serious pathogens of cereal crops, with the greatest effects being in savanna agriculture in Africa. It also causes considerable crop losses in other regions, including other tropical and subtropical crops in its native range and in the Americas.

<i>Cronartium ribicola</i> species of fungus

Cronartium ribicola is a species of rust fungus in the family Cronartiaceae that causes the disease white pine blister rust.

<i>Calocedrus decurrens</i> species of plant

Calocedrus decurrens, with the common names incense cedar and California incense-cedar, is a species of conifer native to western North America, with the bulk of the range in the United States, from central western Oregon through most of California and the extreme west of Nevada, and also a short distance into northwest Mexico in northern Baja California. It grows at altitudes of 50–2,900 metres (160–9,510 ft). It is the most widely known species in the genus, and is often simply called 'incense cedar' without the regional qualifier.

<i>Phoradendron</i> genus of plants

Phoradendron is a genus of mistletoe, native to warm temperate and tropical regions of the Americas. The center of diversity is the Amazon rainforest. Phoradendron is the largest genus of mistletoe in the Americas, and possibly the largest genus of mistletoes in the world. Traditionally, the genus has been placed in the family Viscaceae, but recent genetic research acknowledged by the Angiosperm Phylogeny Group shows this family to be correctly placed within a larger circumscription of the sandalwood family, Santalaceae.

Parasitic plant type of plant that derives some or all of its nutritional requirements from another living plant

A parasitic plant is a plant that derives some or all of its nutritional requirement from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All parasitic plants have modified roots, called haustoria, which penetrate the host plant, connecting them to the conductive system – either the xylem, the phloem, or both. For example, plants like Striga or Rhinanthus connect only to the xylem, via xylem bridges (xylem-feeding). Alternately, plants like Cuscuta and Orobanche connect only to the phloem of the host (phloem-feeding). This provides them with the ability to extract water and nutrients from the host. Parasitic plants are classified depending as to the location where the parasitic plant latches onto the host and the amount of nutrients it requires. Some parasitic plants are able to locate their host plants by detecting chemicals in the air or soil given off by host shoots or roots, respectively. About 4,500 species of parasitic plant in approximately 20 families of flowering plants are known.

Mistletoebird species of bird

The mistletoebird, also known as the mistletoe flowerpecker, is a species of flowerpecker native to most of Australia and also to the eastern Maluku Islands of Indonesia in the Arafura Sea between Australia and New Guinea. The mistletoebird eats mainly the berries of the parasitic mistletoe and is a vector for the spread of the mistletoe's seeds, through its digestive system.

<i>Nectria cinnabarina</i> species of fungus

Nectria cinnabarina, also known as coral spot, is a plant pathogen that causes cankers on broadleaf trees. This disease is polycyclic and infects trees in the cool temperate regions of the Northern Hemisphere. N. cinnabarina is typically saprophytic, but will act as a weak parasite if presented with an opportunity via wounds in the tree or other stressors that weaken the tree’s defense to the disease. A study published in 2011 showed that this complex consists of at least 4 distinct species. There are only a few ways to manage this disease with techniques such as sanitation and pruning away branches that have the cankers. N. cinnabarina is not as significant a problem as other Nectria spp., some of which are the most important pathogens to infect hardwood trees.

The plant pathogenic fungus Leucostoma kunzei is the causal agent of Leucostoma canker a disease of spruce trees found in the Northern Hemisphere, predominantly on Norway spruce and Colorado blue spruce. This disease is one of the most common and detrimental stem diseases of Picea species in the northeastern United States, yet it also affects other coniferous species. Rarely does it kill its host tree; however, the disease does disfigure by killing host branches and causing resin exudation from perennial lesions on branches or trunks.

<i>Arceuthobium americanum</i> species of plant

Arceuthobium americanum is a species of dwarf mistletoe known as American dwarf mistletoe and lodgepole-pine dwarf mistletoe. It is a common plant of western North America where it lives in high elevation pine forests. It is a parasitic plant which lives upon the Lodgepole Pine, particularly the subspecies Pinus contortus ssp. murrayana, the Tamarack Pine. This pine subspecies is most common in the Cascade Range and Sierra Nevada. The American dwarf mistletoe is a yellow-green coral-shaped structure above the surface of the tree's bark, while most of the parasite is beneath the bark. The seeds mature in late summer and disperse to nearby trees. This species has been found to explosively-disperse its seeds through thermogenesis.

<i>Phoradendron leucarpum</i> species of plant

Phoradendron leucarpum is a species of mistletoe in the Viscaceae family which is native to the United States and Mexico. Its common names include American mistletoe, eastern mistletoe, hairy mistletoe and oak mistletoe. It is native to Mexico and the south eastern half of the continental US. It is hemiparasitic, living in the branches of trees. The berries are white and 3–6 millimeters (0.12–0.24 in). It has opposite leaves that are leathery and thick. Ingesting the berries can cause "stomach and intestinal irritation with diarrhea, lowered blood pressure, and slow pulse". This shrub can grow to 1 meter (3.3 ft) by 1 meter (3.3 ft).

<i>Phoradendron juniperinum</i> species of plant

Phoradendron juniperinum is a species of flowering plant in the sandalwood family known by the common name juniper mistletoe. It is native to the southwestern United States and northern Mexico, where it grows in various types of woodland habitat. It has been reported from California, Nevada, Arizona, New Mexico, Oregon, Utah, Texas, Chihuahua and Sonora.

Phoradendron libocedri is a species of flowering plant in the sandalwood family known by the common name incense-cedar mistletoe. It is native to western North America from Oregon to Baja California, where it grows in forests on its host tree, the California incense-cedar.

<i>Dendrophthoe falcata</i> species of plant

Dendrophthoe falcata is one of the hemiparasitic plants that belong to the mistletoe family Loranthaceae. It is the most common of all the mistletoes that occur in India. At the moment reports say that it has around 401 plant hosts. The genus Dendrophthoe comprises about 31 species spread across tropical Africa, Asia, and Australia among which 7 species are found in India.

<i>Lysiana exocarpi</i> species of plant

Lysiana exocarpi, commonly known as harlequin mistletoe, is a species of hemiparasitic shrub, endemic to Australia. It is in the Gondwanan family Loranthaceae and is probably the most derived genus of that family with 12 pairs of chromosomes. The Loranthaceae is the most diverse family in the mistletoe group with over 900 species worldwide and including the best known species in Australia. Mistletoes are notable for their relationships with other species. In an early reference to the group in Australia Allan Cunningham explorer and first Director of the Royal Botanic Gardens, Sydney, wrote in 1817: "The Bastard Box is frequently much encumbered with the twining adhering Loranthus aurantiacus which 'Scorning the soil, aloft she springs, Shakes her red plumes and claps her golden wings'."

Phomopsis blight of juniper species of fungus

Phomopsisblight of juniper is a foliar disease discovered in 1917 caused by the fungal pathogen Phomopsis juniperovora. The fungus infects new growth of juniper trees or shrubs, i.e. the seedlings or young shoots of mature trees. Infection begins with the germination of asexual conidia, borne from pycnidia, on susceptible tissue, the mycelia gradually move inwards down the branch, and into the main stem. Management strategies mainly include removing and destroying diseased tissue and limiting the presence of moisture on plants. Junipers become resistant to infection as they mature and the young yellow shoots turn dark green. Preventative strategies include planting only resistant varieties and spraying new growth with fungicide until plants have matured.

<i>Arceuthobium pusillum</i> species of plant

Arceuthobium pusillum is a perennial, obligate parasitic plant in the sandalwood family. Its common names include Dwarf mistletoe or Eastern dwarf mistletoe. It is one of the most widespread dwarf mistletoes within its range which covers the eastern United States and Canada, from Saskatchewan to Nova Scotia and New Jersey. The species name "pusillum" derives from Latin "pusillus", meaning very small.

<i>Viscum minimum</i> species of plant

Viscum minimum is a species of mistletoe in the family Santalaceae. It is a parasitic plant native to South Africa.

References

  1. ↑ Krautwurst, Terry. “ The truth About Mistletoe.” Mother Earth News, 195 (2003): 26-29
  2. ↑ Hiller, Julie Brooks. “Marvelling at Mistletoe.” Highlights for Children. 65, no 12:40-41
  3. 1 2 "Mistletoe Article". Ag.arizona.edu. Archived from the original on 2010-07-26. Retrieved 2011-10-26.
  4. ↑ Aukema, J. E. 2004. Distribution and Dispersal of Desert Mistletoe is Scale-Dependent, Hierarchically Nested. Ecography 27. pp. 137-144.
  5. 1 2 3 4 Geils, B.W., Wiens, D., Hawksworth, F. G. Phoradendron in Mexico and the United States. USDA Forest Service Gen Tech. Rep. 2002
  6. 1 2 W T Watson, T Martinez-Trinidad. Strategies and treatments for leafy mistletoe (Phoradendron tomentosum (DC.) Engelm ex. Gray) suppression on cedar elm (Ulmus crassifolia Nutt.) Arboriculture and Urban Forestry (2006) Volume: 32, Issue: 6, Pages: 265-270
  7. ↑ Lichter, John M.; Reid, Michael S.; Berry, Alison M. NEW METHODS FOR CONTROL OF LEAFY MISTLETOE (PHORADENDRON SPP.) ON LANDSCAPE TREES. 1991. Journal of Arboriculture. 17(5). pp. 127-130.
  8. ↑ Solomon, J.D.; Leininger, T.D.; Wilson, A.D.; Anderson, R.L.; Thompson, L.C.; McCracken, F.I. 1993. Ash pests: A guide to major insects, diseases, air pollution injury and chemical injury. Gen. Tech. Rep. SO-96. New Orleans, LA: U.S. Department of Agriculture, Forest Service, and Southern Forest Experiment Station. 45 p.
  9. ↑ Insects and Diseases of Trees in the South. 1989. USDA Forest Service - Forest Health Protection. R8-PR16. 98 pp. Taken from http://fhpr8.srs.fs.fed.us/forstpst.html
  10. ↑ Hull, Richard J.; Leonard, Oliver A. Physiological Aspects of Parasitism in Mistletoes (Arceuthobium and Phoradendron). The Carbohydrate Nutrition of Mistletoe.
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