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The Propagation of Christmas trees is the series of procedures carried out to grow new Christmas trees.
Many different species of evergreen trees are used for Christmas trees. The most common of these species are classified in the four genera: pines, spruces, firs, and cypress. Christmas trees can be grown from seed or from root cuttings.
There are many different species of evergreen trees that are used for Christmas trees. [1] The most common of these species are classified in one of four genera: pines (genus Pinus), spruces (genus Picea), firs (genus Abies), and cypress (genus Cupressa). In addition to these, the Douglas fir (Pseudotsuga Menziesii) is also commonly used as a Christmas tree, but it is not a true fir. [2] The varieties of trees that a nursery chooses to propagate is dependent upon what type of farm is buying the reproduced plant, the climate of the nursery, the climate of the tree farm where the trees are to be grown, and the preferences of the retail customers.
The most commonly grown species include Eastern White pine, Virginia pine, Scotch pine, Colorado Blue spruce, Norway spruce, Serbian spruce, White spruce, Balsam fir, Grand fir, Frasier fir, Canaan fir, Noble fir, Turkish fir, White fir, Blue Ice Carolina and Sapphire cypress (both are sterile hybrids of the Arizona cypress), Leyland cypress, Eastern Red cedar, and Douglas fir. [3] [ citation needed ] These trees have become popular because of their appearance, color, aroma, texture, or a combination of these properties. The Norway spruce, Serbian spruce, Scotch pine, and Turkish fir are not native to the United States. [4] However, genetic variations within these species have allowed some varieties to be grown in climates that differ substantially from the climate where the species originated. The Eastern White pine is native to the eastern U.S. The Colorado Blue Spruce is native to Colorado and Utah. The White spruce is native to the north-central U.S. and Canada. The Noble, Douglas, and Grand firs are both native to the northwest of the U.S. The Balsam fir is native to the northeastern U.S. [5] The Canaan fir is native to the Canaan Valley of West Virginia. The White fir is native to California and the Southwestern mountains of the U.S. [6] From these varied trees, Christmas tree nurseries must select varieties to propagate based on the climate of their region and the type of farms that they will be selling to.
Fresh cut tree farms are generally large farms that grow trees that are cut in large numbers and sold to wholesalers who sell them to local stores and Christmas tree lots. The extended period of time that elapses from the time of cutting the tree until the retail customer takes the tree home limits the number of species of trees that can be used as fresh cut trees. These trees must be able to retain their color and their needles for long periods of time after they are cut. The most common species that are grown as fresh cut trees are Frasier fir, Scotch pine, Douglas fir, and Balsam fir. Since fir trees generally require cooler climates, nurseries that primarily propagate trees for fresh cut tree farms are typically located in the northern United States.
Choose-and-cut tree farms are typically smaller than fresh cut tree farms because they sell in smaller quantities than fresh cut tree farms. They typically sell directly to the customer who chooses and then cuts his or her own tree. Since the trees are cut at the moment of purchase, the limitations of the farm are primarily due to the farm’s geographic location. Needle and color retention are much less of a concern because of the freshness of the trees. For this reason, Christmas tree nurseries that propagate trees for sale to choose-and-cut tree farms typically sell more species of trees and can be located closer to the Mason–Dixon line. Some nurseries that specialize in cypress trees are located as far south as Florida.
The geographic location of the Christmas tree nursery dictates what species of trees can be propagated. White and Scotch pines are relatively adaptable species of trees. Because many genetically different varieties are available, they can be grown in most of the temperate areas of the United States. True firs generally prefer a much cooler climate and are primarily grown in the northern United States, with some varieties that only thrive in mountainous climates. Spruce prefer cool climates, but they will tolerate warmer conditions than most fir trees. Cypress generally prefer a warmer climate. For this reason, they are grown primarily in the southern and southwestern United States. The Douglas fir is a fairly adaptable species and can be grown in much of the United States. In addition to the nursery’s location, the type and location of farms that purchase the seedlings or rooted cuttings also plays an important role in the type of tree that is propagated.
Christmas tree propagation internationally has similar issues of geographical limitation, such as in Australia where the seasons for pruning and harvest differ from the northern hemisphere. [7] Additionally, the environment of Australia favours the growth of Pinus radiata [8] which is no longer commonly grown in the northern hemisphere.
The selection of the correct seed for a specific environment and the proper preparation of the seeds prior to planting are necessary to ensure germination and survival of the seedling.
The selection of seed source by the tree nursery is critical. The specific variety that is selected must meet the needs of its customers and be capable of germinating and growing in the climate where the nursery is located. The variety must also be able to thrive in the region where the tree farm that is purchasing the seedlings is located. Genetic variations within the species of conifers that are used for Christmas trees have produced individual varieties of trees that can thrive in certain climates where other varieties of the same species cannot. This same genetic variation can also produce trees that are aesthetically more pleasing than others. Knowledge of the seed source allows the nursery to provide trees that are suitable for their customer specific locations and needs as well as satisfy the desires of the end-purchaser who will take the tree home for Christmas. Scientists are working on methods to reduce the costs of artificially producing seeds for White spruce, Norway spruce, and Douglas fir through somatic embryo production in a liquid medium. This method uses the living cells of one tree to produce man-made seeds that will produce a clone of the original plant. [9] If the costs are reduced significantly, this could result in nearly perfect Christmas trees. However, this will create a monoculture crop which may be susceptible to a single pest or disease.
Viable seeds produced by a mature tree undergo Stratification. [2] This process imitates the period of dormancy that occurs during the winter. [2] In the commercial Christmas Tree nurseries of the northern United States, seeds are sown directly into seed beds in the late fall to allow the seeds to stratify naturally over the winter. Stratification can also be achieved by refrigerating moist seeds from 30 to 90 days. The commercial method typically yields a higher percentage of germination than artificially reproduced stratification.
After stratification, most seeds need some type of scarification. Scarification is the process that allows the hard shell of the seed to be penetrated by water. This is usually accomplished by soaking the seeds in water for a period of time. In some cases, the seed shell must be scraped with an abrasive to speed up the process. In nature, this process typically occurs through the seed’s immersion in water during the spring melt of snow and ice. It can also occur through the digestive process of an animal that eats the seed and then passes it in its excretion.
Unlike most garden seeds, conifer seeds require shade and cool conditions to germinate. This can be accomplished by placing a thick layer of mulch over the seeded tree bed and erecting a canopy over it to reduce direct sunlight. This simulates the conditions where the seeds would typically germinate naturally
Some species of Christmas trees can only be propagated by root cuttings because they do not produce viable seeds because they are sterile inter-generic hybrids. These cuttings are taken from an existing tree, thus the new trees are clones of the original tree. The Blue Ice cypress, the Leyland cypress, and the Carolina Sapphire cypress are all tree species that must be propagated in this manner. [10]
The selection of the cuttings that are taken is critical to ensure successful rooting and proper growth habits. The cuttings should be taken from upright shoots of trees that are less than 10 years old. Choosing upright shoots ensures apical dominance and upward growth and reduces the possibility of the tree growing laterally like a bush. The cuttings should be taken in late winter or early spring and be 8 to 12 inches long and have some brown coloration near the base of the cutting. [11] The cuttings should be kept in water until they are ready to be placed in rooting media.
Once the cuttings have been acquired, the bases of the cuttings are dipped into rooting hormone and immediately placed in containers filled with porous rooting media to facilitate rooting. Once potted, the rooting media need to be kept moist and the cuttings need to be misted regularly. The cuttings should develop an adequate root system for transplantation in about three months. It has been determined that rooting hormones containing higher levels of IBA increase the percentage of cuttings that develop viable roots in Carolina Sapphire cypress. [11] Studies have also shown that misting at 7- to 10-minute intervals increases the amount of successful root development in Leyland cypress cuttings. [12]
The Douglas fir is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three varieties: coast Douglas-fir, Rocky Mountain Douglas-fir and Mexican Douglas-fir.
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta, also known as Coniferophyta or Coniferae. The division contains a single extant class, Pinopsida. All extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs. Examples include cedars, Douglas-firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews. As of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, and 629 living species.
Fruit tree propagation is usually carried out vegetatively (non-sexually) by grafting or budding a desired variety onto a suitable rootstock.
A spruce is a tree of the genus Picea, a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. Picea is the sole genus in the subfamily Piceoideae. Spruces are large trees, from about 20 to 60 m tall when mature, and have whorled branches and conical form. They can be distinguished from other members of the pine family by their needles (leaves), which are four-sided and attached singly to small persistent peg-like structures on the branches, and by their cones, which hang downwards after they are pollinated. The needles are shed when 4–10 years old, leaving the branches rough with the retained pegs. In other similar genera, the branches are fairly smooth.
A nursery is a place where plants are propagated and grown to a desired size. Mostly the plants concerned are for gardening, forestry, or conservation biology, rather than agriculture. They include retail nurseries, which sell to the general public; wholesale nurseries, which sell only to businesses such as other nurseries and commercial gardeners; and private nurseries, which supply the needs of institutions or private estates. Some will also work in plant breeding.
Plant propagation is the process by which new plants grow from a variety of sources: seeds, cuttings, and other plant parts. Plant propagation can also refer to the man-made or natural dispersal of seeds.
Silviculture is the practice of controlling the growth, composition/structure, and quality of forests to meet values and needs, specifically timber production.
Picea glauca, the white spruce, is a species of spruce native to the northern temperate and boreal forests in North America. Picea glauca is native from central Alaska all through the east, across western and southern/central Canada to the Avalon Peninsula in Newfoundland, and south to Montana, North Dakota, Minnesota, Wisconsin, Michigan, Upstate New York and Vermont, along with the mountainous and immediate coastal portions of New Hampshire and Maine, where temperatures are just barely cool and moist enough to support it. There is also an isolated population in the Black Hills of South Dakota and Wyoming. It is also known as Canadian spruce, skunk spruce, cat spruce, Black Hills spruce, western white spruce, Alberta white spruce, and Porsild spruce.
Taxodium distichum is a deciduous conifer in the family Cupressaceae. It is native to the southeastern United States. Hardy and tough, this tree adapts to a wide range of soil types, whether wet, salty, dry, or swampy. It is noted for the russet-red fall color of its lacy needles.
Ziziphus mauritiana, also known as Indian jujube, Indian plum, Chinese date, Chinee apple, ber, and dunks is a tropical fruit tree species belonging to the family Rhamnaceae. It is often confused with the closely related Chinese jujube, but whereas Z. jujuba prefers temperate climates, Z. mauritiana is tropical to subtropical.
Layering is the process whereby the branch of a tree, or other plant, produces roots and is separated from the original plant, becoming a new, separate plant. Layering is utilized by horticulturists to propagate desirable plants.
A seedling is a young sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle, the hypocotyl, and the cotyledons. The two classes of flowering plants (angiosperms) are distinguished by their numbers of seed leaves: monocotyledons (monocots) have one blade-shaped cotyledon, whereas dicotyledons (dicots) possess two round cotyledons. Gymnosperms are more varied. For example, pine seedlings have up to eight cotyledons. The seedlings of some flowering plants have no cotyledons at all. These are said to be acotyledons.
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.
Christmas tree cultivation is an agricultural, forestry, and horticultural occupation which involves growing pine, spruce, and fir trees specifically for use as Christmas trees.
Pine and fir trees, grown purposely for use as Christmas trees, are vulnerable to a wide variety of pests, weeds and diseases. Many of the conifer species cultivated face infestations and death from such pests as the balsam woolly adelgid and other adelgids. Aphids are another common insect pest. Christmas trees are also vulnerable to fungal pathogens and their resultant illnesses such as root rot, and, in the U.S. state of California, sudden oak death. Douglas-fir trees in particular are vulnerable to infections from plant pathogens such as R. pseudotsugae.
Widdringtonia nodiflora is a species of Widdringtonia native to Southern Africa. It usually grows at high altitudes, typically among rocks on mountainsides. Its foliage and wood are highly flammable while its natural habitat is prone to fire. To compensate, the species will coppice from its roots after being burnt down.
Artocarpus anisophyllus, the entawak or mentawa, is a tropical tree in the Moraceae. It is native to the central parts of Southeast Asia, and is present in Peninsular Malaysia, Sumatra, Borneo and the intervening islands.
Bonsai cultivation and care involves the long-term cultivation of small trees in containers, called bonsai in the Japanese tradition of this art form. Similar practices exist in other Japanese art forms and in other cultures, including saikei (Japanese), penjing (Chinese), and hòn non bộ (Vietnamese). Trees are difficult to cultivate in containers, which restrict root growth, nutrition uptake, and resources for transpiration. In addition to the root constraints of containers, bonsai trunks, branches, and foliage are extensively shaped and manipulated to meet aesthetic goals. Specialized tools and techniques are used to protect the health and vigor of the subject tree. Over time, the artistic manipulation of small trees in containers has led to a number of cultivation and care approaches that successfully meet the practical and the artistic requirements of bonsai and similar traditions.
In horticulture, stratification is a process of treating seeds to simulate natural conditions that the seeds must experience before germination can occur. Many seed species have an embryonic dormancy phase, and generally will not sprout until this dormancy is broken.
A tree plantation, forest plantation, plantation forest, timber plantation or tree farm is a forest planted for high volume production of wood, usually by planting one type of tree as a monoculture forest. The term tree farm also is used to refer to tree nurseries and Christmas tree farms.