Christmas tree cultivation

Christmas tree cultivation is an agricultural, forestry, and horticultural occupation which involves growing pine, spruce, and fir trees specifically for use as Christmas trees.

"Christmas tree farm" redirects here. For the Taylor Swift song, see Christmas Tree Farm.
A Christmas tree farmer in the U.S. state of Florida explains the pruning and shearing process of cultivation to a government employee.

The first Christmas tree farm was established in 1901, but most consumers continued to obtain their trees from forests until the 1930s and 1940s. Christmas tree farming was once seen only as a viable alternative for low-quality farmland, but that perception has changed within the agriculture industry. For optimum yield and quality, land should be flat or gently rolling and relatively free of debris and undergrowth.

A wide variety of pine and fir species are grown as Christmas trees, although a handful of varieties stand out in popularity. In the United States, Douglas-fir, Scots pine and Fraser fir all sell well. Nordmann fir and Norway spruce sell well in the United Kingdom, the latter being popular throughout Europe. Like all conifers, Christmas trees are vulnerable to a range of pests.

The final stage of cultivation, harvesting, is carried out in a number of ways; one of the more popular methods is the pick-your-own tree farm, where customers are allowed to roam the farm, select their tree, and cut it down themselves. Other farmers cultivate potted trees, with balled roots, which can be replanted after Christmas and used again the following year

History

The practice of cultivating evergreens specifically to sell as Christmas trees dates back to 1901, when a 25,000-tree Norway spruce farm was sown near Trenton, New Jersey.[1] The commercial market for Christmas trees had started 50 years earlier when a farmer from the Catskill Mountains brought trees into New York City to sell.[2] Despite these pioneering efforts, most people still obtained wild-grown Christmas trees from forests into the 1930s and 1940s.[3] More trees were grown in plantations after World War II, and by the 1950s, farmers were shearing and pruning trees to meet customer demands. The Christmas tree market burgeoned through the 1960s and 1970s, but from the late 1980s onward, prices and the market for natural Christmas trees declined. In the early 21st century, nearly 98% of all natural (not artificial) Christmas trees sold worldwide were grown on tree farms.[4]

Cultivation

Land and climate
This Christmas tree farm in southern Virginia is situated in a gently rolling valley.

Christmas tree farms are best located on relatively level land that is free of obstructions. In the past, Christmas tree farmers established their plantations on less desirable agricultural plots or "wastelands of agriculture".[5] However, emphasis in modern Christmas tree farming has shifted toward the production of higher-quality trees, and increasing land quality expectations.[5] Indeed, some species of trees, such as the Fraser fir, are unable to grow on low-quality, marginal farmland.[6] Flat or gently rolling land is preferred to that with steep slopes and inclines, which is prone to erosion and fluctuations in fertility. Noticeable obstructions, such as rocks, fences, or significant underbrush, are also undesirable.[5]

This Christmas tree farm in Iowa is located on flat ground and has well-mowed rows between the trees.

Like all crops and plants, Christmas trees require a specific set of nutrients to thrive.[7] Some 16 elements are crucial for growth; of those, three are obtained through air and water: hydrogen, carbon, and oxygen. Nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, chlorine, manganese, molybdenum, iron, and zinc are obtained from the soil. If the necessary elements are not available in the local soil, nutritious fertilizers are used.[7] Other important soil considerations include pH and drainage.[8] Certain types of soil are preferable, depending on the type of tree. Pine trees are usually better adapted to a sandy or sandy loam soil,[9] while white spruce trees and fir trees, such as the Douglas fir, prefer fine-texture loams and clay loam soils.[9] Some trees grow well in all types of soil, but in any case, the land must be well-drained for a Christmas tree farm to have a chance of thriving.[9]

The weather, as with other agricultural endeavors, plays a key outcome in the yield of a Christmas tree farm. Severe cold in the winter and extreme hot and dry conditions during and after harvest can cause irreparable damage to the crop.[10] Early snow can make both harvesting and shipping trees difficult or impossible.[10]

Labor and equipment

Christmas tree farming is a labor-intensive process. Depending on the quality of the land, bulldozing may need to be undertaken prior to planting, to remove obstacles such as large trees or rocks.[11] If the volume of undergrowth requires it, the soil may be tilled; tilling can help remove any debris remaining after tree or weed removal. Both woody plants and herbaceous weeds must be controlled prior to planting; this is most often done by application of a chemical herbicide.[11] In addition, some types of fertilizers must be introduced into the soil prior to planting.[11] The work done before planting tree seedlings plays an important role in the overall success of a Christmas tree crop.[10]

After the trees are in the ground, work on the crop continues. Animal pests (especially insects) and diseases must be monitored and controlled, and weed growth must also be minimized. Many species of pine and fir require pruning and shearing two to four years after planting to maintain the classic Christmas tree shape.[10] Late or omitted pruning can result in trees that are unmarketable due to large gaps in needle coverage. Some species of pine, such as the Scots pine, are susceptible to dormant season "yellowing", which is generally countered with a green dye or paint.[10][12]

The outlay of money on equipment varies greatly. Some items commonly found on Christmas tree farms are insecticide sprayers, tractors, and shaper sheers.[13] Mechanized planters, at a cost of about US$4,000, are not essential but a work-saving luxury for farmers.[13] Farmers can purchase seedlings, the lifeblood of a Christmas tree farm, from nurseries. One farmer in Oregon purchased seedlings for US$200–300 per 1,000 plants. The farmer, a wholesaler, sold his final products for about $20 each; after the cost of the trees and other expenses, a profit of $2–3 per tree.[13]

Trees
Fraser fir (cone and foliage pictured) is a popular species of Christmas tree in both the United States and Great Britain.

The best-selling species in the North American market are Scots pine, Douglas fir, noble fir, balsam fir, Fraser fir, Virginia pine, and eastern white pine, although other types of trees are also grown and sold.[4][14] In Alabama, for example, types of trees grown for use as Christmas trees include eastern white pine, redcedar, Virginia pine, Leyland cypress, and Arizona cypress.[15] In Florida, the sand pine and spruce pine are among the 20,000 grown in the state each year.[16]

Norway spruce is a popular Christmas tree species in Europe.

In Great Britain, Nordmann fir is a popular species, largely due to its needle-holding qualities.[17][18] Other popular trees in Britain are Norway spruce, Serbian spruce, and Scots pine, the last of which is slightly rarer;[18] it has sharp needles that do not shed easily.[17]

In the U.S. Pacific Northwest, a major Christmas tree growing region, Douglas fir has always been the primary species grown.[19] A full one-half of all trees produced in the Pacific Northwest are Douglas fir.[19] Douglas firs typically take five to seven years before they are mature enough to sell as Christmas trees.[19] Also common in the region are noble fir, a tree that commands a higher price than Douglas fir, and grand fir, which accounts for about 10% of the annual harvest in the Northwest.[19] Other species collectively account for only 3–5% of the total Northwest harvest.[19]

In North America, Fraser fir, grown in the Appalachian Mountains of North Carolina, has been called the "Cadillac of Christmas Trees", as well as the "most popular and most valuable of Christmas tree species".[20] In the Southern United States, Virginia pine is a popular Christmas tree species.[21] In Canada, white pine, white spruce, Scots pine, blue spruce, and Fraser fir are commonly cultivated.[22] In the province of Ontario, Scots pine has always dominated both the domestic and export markets.[22] Other regions of the world also have different favorites of natural Christmas trees, and Christmas tree farms reflect these; In Europe, Norway spruce is popular.[21]

Pests, disease and weeds
Main article: Christmas tree pests and weeds
An adult balsam woolly adelgid, a major pest in the Christmas tree industry

Many of the conifer species cultivated face infestations and death from such pests as the balsam woolly adelgid, other adelgids, and aphids. Invasive insect species, such as the pine shoot beetle and the gypsy moth, also threaten Christmas tree crops.[23] Christmas trees are also vulnerable to fungal pathogens, resulting in such illnesses as root rot, and, in California, Washington, Oregon and British Columbia sudden oak death.[24] Douglas-fir trees are especially vulnerable to infections from plant pathogens such as R. pseudotsugae and Rhabdocline weirii; R. weirii affects only Douglas fir trees.[25][26] The pathogen often makes Douglas fir trees unsaleable as Christmas trees and heavily affects the Christmas tree farming industry.[25]

Mammals such as deer, gophers, and ground squirrels are also threats to Christmas tree crops, due to the damage they cause to roots and buds. Certain species of birds are also considered pests, including the pine grosbeak, which feeds on conifer buds,[27] usually affecting Scots pine but also affecting eastern white pine and red pine, as well as spruce trees.[28] Herbaceous weeds, as well as woody plants, also compete with Christmas tree crops for water and nutrients, necessitating control methods including mowing, chemical herbicide use, and tilling.

Quality
USDA Christmas Tree Grades[29]
Grade Requirements[30]
U.S. Premium Fresh, clean, healthy, heavy density, one minor defect allowed[31]
U.S. No. 1 Fresh, fairly clean, healthy, medium density, two minor defects allowed[32]
U.S. No. 2 Fresh, fairly clean, healthy, light density,
three minor defects allowed[33]

Christmas tree quality grades have been in place since 1965 in Ontario, Canada, and were included under the provincial Farm Products Grades and Sales Act.[22] While the grades in Ontario are law, in the United States the grading system is not mandated. In fact, it is common for U.S. growers to develop their own grading systems.[34] The grading systems established by individual jurisdictions are often in the spirit of the U.S. Department of Agriculture's (USDA) grading scheme, even if they are not entirely based upon them.[35] The Department of Agriculture's United States Standards for Grades of Christmas Trees took effect on October 30, 1989, covering "sheared or unsheared trees of the coniferous species which are normally marketed as Christmas trees".[29]

Harvest
See also: Christmas tree production
Customers, armed with a saw, at a typical "choose-and-cut" Christmas tree farm

Christmas trees can be harvested and marketed in different ways. Some operations are known as "choose-and-cut" or pick-your-own farms, which allow customers to walk through the planted land, select their Christmas tree and cut down themselves.[8] Wholesale operations are more labor-intensive because they usually require the farmer to complete tasks such as baling, cutting, moving the trees to a roadside pick-up, and loading the harvest. In addition, this work must be completed during a very short period in November.[8] Growers also harvest trees by digging and balling the root and selling the trees as nursery stock or as live, reusable Christmas trees. This last option allows trees to be harvested earlier than the usual six- to ten-year period required to grow a mature Christmas tree.[8]

Customers haul their own purchases off-site at choose-and-cut farms.

Larger farms began using helicopters to move tree harvests during the 1980s.[3] One 1,200-acre (490 ha) farm in Oregon lacked road access, so it began using helicopters to move up to 200,000 Christmas trees per year.[36] Helicopters reduce the amount of time between harvesting and market, cutting it from up to two weeks down to as little as three days.[36]

Not all natural Christmas trees harvested are grown on plantations. In British Columbia, Canada, for example, most of the 900,000 trees harvested for use as Christmas trees came from native pine and fir stands.[37] The British Columbia Ministry of Forests and Ranges allows any resident of the province to cut a Christmas tree for free from Crown Lands, provided the individual receive prior permission in writing from a forest officer.[38] In the United States, the U.S. Forest Service and the Bureau of Land Management offer permits for individual tree cutting on government land, mostly within the National Forest system.[39]

Farmers

The people who operate Christmas tree farms range from full-time growers to part-time farmers. One farmer in Minnesota, who began planting Christmas trees in 1967, gave his trees away for free from his modest 1-acre (4,000 m2) farm for ten years before establishing a tree farming business.[40] Other farmers started growing Christmas trees as a supplemental income for retirement or college funds,[41][42] or they worked farms that were not originally established as Christmas tree farms.[43][44]

Various national growers' associations have been founded in Christmas tree producing nations. In the United Kingdom, the British Christmas Tree Growers Association is a trade association open to membership from Christmas tree farmers in Great Britain and Northern Ireland.[45] The National Christmas Tree Association serves a similar function in the United States.[46]

Environmental effect

In the United States, the National Christmas Tree Association (NCTA) promotes the environmental benefits of live Christmas trees over the competing artificial alternative.[47] The NCTA stated that every acre of Christmas trees in production produced the daily oxygen requirement for 18 people; with 500,000 acres (200,000 ha) in production in the U.S. alone, that amounts to oxygen for 9 million people per day.[47] The NCTA also stated that the farms help to stabilize the soil, protect water supplies and provide wildlife habitat.[47] In addition, the industry points to the reduction of carbon dioxide through Christmas tree farming.[48] An independent Life Cycle Assessment (LCA) study, conducted by a firm of experts in sustainable development, states that a natural tree will generate 3.1 kg of greenhouse gases whereas the artificial tree will produce 8.1 kg per year.[49]

A 1998 report from the Michigan State University Agricultural Experiment Station predicted increasing environmental concerns about tree production and use as one possible reason people may favor artificial trees in the future. The report cited the use of fertilizers and pesticides and increasing concerns regarding tree disposal as the chief elements in its prediction.[50] Critics of tree farming have raised the concerns highlighted in the 1998 report, as well as other issues, such as the effect that large-scale tree farming operations have on biodiversity.[48] Pesticide use on Christmas tree farms is one of the main concerns of environmentalists;[48][51] fir trees are vulnerable to a wide array of pests and diseases which requires the use of pesticides and other chemicals including the widely used herbicide glyphosate.[48] Glyphosate is commonly used in Christmas tree production in the U.S. state of North Carolina, where studies have found traces of agricultural chemicals in homes and tree industry workers' urine samples.[48] The average Christmas tree receives roughly a half of an ounce (14 g) of pesticide over its lifetime.[51]

The BBC's "Gardening" website called buying Christmas trees directly from the farm, "the most environmentally friendly way of getting a tree".[18] Other positive environmental attributes have been given live Christmas trees as well. Researchers at the University of Nebraska included the reuse of natural Christmas trees as mulch and, in larger quantities, piled up as soil erosion barriers, among the benefits of live tree use.[52] Other positive reuses included fish habitat in private ponds and backyard bird feeders.[52]

Research

Since 2004, several researchers at Oregon State University's (OSU) College of Forestry have researched various aspects of Christmas tree cultivation. In the Department of Forest Resources, Rick Fletcher is researching Christmas tree genetics, fertilization and disease management, while Chad Landgren is concentrating his emphasis on Christmas tree genetics and disease management. Both men are doing their research in the Silviculture and Ecology Section of the department.[53] In OSU's Department of Forest Science, Mike Bondi is conducting ongoing research into Christmas tree fertilization, productivity and genetics, as well as natural and artificial regeneration systems.[54] During the mid-1990s, the trio's research was primarily focused on creating better Christmas tree seed stock, resulting in a higher percentage of quality mature trees, through genetic improvements.[55] Similar research has been conducted by the Agricultural Experiment Station at New Mexico State University.[56]

U.S. institutions in other Christmas tree producing locales have also undertaken their own research programs. North Carolina State University has several full-time staff dedicated to all aspects of tree production.[57] Specialties at N.C. State cross several academic departments and range from a Christmas tree genetics program to providing material support for growers in areas such as sustainable agriculture and pest management.[57]

The Christmas Tree Research Center in Bible Hill, Nova Scotia does research on Balsam firs for Canadian producers.[58]

Industry classification

Activities related to the cultivation of Christmas trees require cross-disciplinary (forestry, horticulture, and agriculture) skills and fall into different specialty categories. Under the terms of Title 29 of the United States Code, which defines federal regulations pertaining to the United States Department of Labor, Christmas tree planting, tending and cutting are specifically not "farming operations".[59] The U.S. Farm Service Agency (FSA) does not provide federal crop insurance for Christmas tree crops, however, there is an alternative program, through the FSA, which provides assistance for non-insured crops.[60] The U.S. Census Bureau, responsible for the Agriculture Census until 1997, excluded Christmas tree farms as farms from its reports. When the Census of Agriculture authority was shifted to the U.S. Department of Agriculture in 1997 the differences in definition were resolved and the Census of Agriculture included Christmas tree farms.[61]

The status of Christmas tree farms as actual, by definition, farms, and their products thus agricultural in nature, has evolved in the various government agencies responsible for such categorization. In both Canada, and the United States the governments take a regular Census of Agriculture, reporting in these censuses relies on the classifications.[62] Beginning in 1996, the Canadian government included Christmas tree farms in its Census of Agriculture concerning the issue of net farm income and farm cash receipts. The changes also included the addition of egg hatcheries to the census.[62] The results were marginal with net cash farm income rising just 0.1 percent.[62]

In the United Kingdom, Christmas trees do not fall into the category of enterprises included in farm profits.[63] Instead, Christmas tree farms are classified as "market gardens".[63] Market gardens are defined separately from farming and are nurseries or gardens used for the sale of produce other than hops.[63] However, in Northern Ireland, some Christmas trees are cultivated and harvested by the Forest Service.[64]

Cultural significance
This reindeer, at a tree farm in Seattle, is part of the holiday-themed extras offered by many Christmas tree farms.

In the United States, visits to Christmas tree farms have become a Christmas holiday tradition for people.[40][41] Christmas tree farms have embraced this trend; at one Minnesota tree farm it has become tradition for customers to pose for snapshots with their trees, when they return in subsequent years they can check the "wall of memories" for their photo.[40] Other tree farms have served the same families for multiple generations, becoming a part of each group's holiday traditions.[41][65] In 2006, New York state Agriculture Commissioner Patrick H. Brennan, supported the virtues of purchasing Christmas trees from local Christmas tree farms.[66] In a statement released to support New York Christmas tree growers he stated,

It is a tradition in my family to visit our local tree farm and harvest our family's Christmas tree. It is a wonderful event for the whole family and if you don't already do so, I encourage you to share this tradition with your family.[66] –NY Agriculture Commissioner Patrick H. Brennan, 2006

Some tree farms offer more than just a chance to cut down a live Christmas tree. Outdoor and holiday themed activities are not uncommon and include wagon rides, offering hot cocoa or cider, Santa Claus visits and holiday crafts.[67] Many tree farms actively encourage schools to sponsor field trips to the farms. One grower in Kansas contended that usual worries for businesses, such as a tight economy, do not affect Christmas tree farms.[68] The grower thought that obtaining a tree from a Christmas tree farm was something that almost nothing could stop; an activity that transcended the economy and the weather.[68]

See also

Notes
  1. Faber Harold. Off to the farm for a Christmas tree, The New York Times, December 2, 1990, p. 17. Retrieved September 5, 2007.
  2. Summers, Will. From Seed to Santa – A Tale of a Christmas Tree, Oregon Employment Department, November 28, 2005.
  3. Chastagner and Benson, The Christmas Tree: Traditions, Production and Diseases.
  4. Wolford, Christmas Tree Facts.
  5. Brown, et al., Bulletin 670: Choice of Lands for Christmas Trees.
  6. Leuty, Todd. Fraser Fir for Christmas Trees and Landscape Transplants Archived July 6, 2011, at the Wayback Machine, Ministry of Agriculture, Food and Rural Affairs (Ontario), May 1, 2005. Retrieved September 6, 2007.
  7. Hart, et al., Christmas Tree Nutrient Management Guide for Western Oregon and Washington.
  8. Johnson, et al., Tree Crops for Marginal Farmland: Christmas Trees With a Financial Analysis.
  9. Koelling and Dornbush, Growing Christmas Trees in Michigan.
  10. Barney and Finnerty, Christmas trees is this the crop for you?.
  11. Brown, et al., Bulletin 670: Plantation Establishment and Management: Preplanting Land Preparation.
  12. Lane, Pirjetta, et al. Christmas tree production in Iowa, (PDF file), Cooperative Extension Service, Iowa State University, December 1992. Retrieved September 6, 2007.
  13. Preston, For a Very Merry Christmas, Invest in Trees for the Season. International Herald Tribune.
  14. Christmas Tree Facts Archived 2006-09-22 at the Wayback Machine, Plant Materials Program, National Resources Conservation Service, December 16, 2003; January 23, 2006. Retrieved September 3, 2007.
  15. Fischman, Bernice and Tilt, Ken. History of the Christmas Tree Archived 2007-06-29 at the Wayback Machine, College of Agriculture - Horticulture, Auburn University. Retrieved July 14, 2007.
  16. McEleroy, Terance. Florida-Grown Christmas Trees Presented To Governor Bush And Commissioner Bronson Archived 2010-12-02 at the Wayback Machine, (press release), Florida Department of Agriculture and Consumer Services, December 5, 2006. Retrieved September 3, 2007.
  17. Anonymous, Metro (London), Tree shortage threatens Christmas.
  18. Christmas tree, Gardening, BBC. Retrieved 3 September 2007. Archived December 13, 2007, at the Wayback Machine
  19. Bondi, An Introduction to Growing Christmas Trees.
  20. Vukina, Tomislav, et al. (2001). A Hotelling-Faustmann Explanation of the Structure of Christmas Tree Prices. American Journal of Agricultural Economics 83 (3): 513-525.
  21. Wolford, Tree Types.
  22. Leuty, Christmas tree production.
  23. Division of Communications: Untitled story Archived September 26, 2007, at the Wayback Machine, Outdoor Indiana, November/December 2006, Indiana Department of Natural Resources. Retrieved September 4, 2007.
  24. Sudden Oak Death (SOD) - Phytophthora ramorum Archived 2007-12-14 at the Wayback Machine, City of Victoria (British Columbia), Parks, Recreation & Community Development: Parks Division. Retrieved 11 September 2007.
  25. Cornell University, Rhabodocline Needlecast (Rhabdocline weirii).
  26. How To Identify and Control Rhabdocline and Swiss Needlecasts of Douglas-Fir, North Central Forest Experiment Station United States Forest Service, 1983. Retrieved September 7, 2007.
  27. Christmas Tree Pest Manual, Index A. Retrieved September 7, 2007.
  28. Christmas Tree Pest Manual, Shoot/Branch Injury, Table of Contents. Retrieved September 7, 2007.
  29. United States Department of Agriculture, "United States Standards for Grades of Christmas Trees".
  30. The table lists only a portion of the requirements for each grade. Each grade consists of 12 requirements. See United States Standards for Grades of Christmas Trees.
  31. The 12 requirements a tree must possess for the "U.S. Premium" grade are: characteristics typical of the species, butt trimmed (except for trees graded "on the stump"), normal taper, fresh, clean, healthy, well-shaped, not less than heavy density, handle length cannot exceed 6 inches (15 cm), or more than 1+1⁄2 inches (3.8 cm) for each foot (.3 m) of height (except for trees graded "on the stump"), in total three faces must not have more than one "minor defect", the other face may have only one minor defect. The final two requirements have to do with size and a few exceptions for cases where entire lots are required to meet the grade. See United States Standards for Grades of Christmas Trees.
  32. The 12 requirements a tree must possess for the "U.S. No. 1" grade are the same as U.S. Premium except for fairly clean, instead of clean, not less than medium density, and in total three faces must not have more than two "minor defects", the other face may have only one "noticeable defect". The final two requirements are also the same as those for the U.S. Premium grade.
  33. The 12 requirements a tree must possess for the "U.S. No. 2" grade are the same as U.S. Premium except for fairly clean, instead of clean, not less than light density, and in total two adjacent faces must not have more than three "minor defects", the other faces may have two "noticeable defects". The final two requirements are also the same as those for the U.S. Premium grade.
  34. Brown, James H., et al. Bulletin 670: Harvesting the Christmas tree crop, Ohio Christmas Tree Producers Manual, Ohio State University. Retrieved September 6, 2007.
  35. Wholesale, New Hampshire-Vermont Christmas Tree Association, official site. Retrieved 6 September 2007.
  36. Kalkstein, KVAL News Channel 13 (Eugene, Oregon), "Christmas tree harvest".
  37. Christmas Trees Archived 2007-06-20 at the Wayback Machine, BC Farm Products A–Z, British Columbia Ministry of Agriculture and Lands. Retrieved September 7, 2007.
  38. Okanagan Shuswap Forest District, Information on cutting free Christmas Trees for Personal Use, British Columbia Ministry of Forests and Ranges. Retrieved September 10, 2007.
  39. Christmas tree permits Archived November 14, 2007, at the Wayback Machine, United States Forest Service, December 3, 2000. Retrieved September 10, 2007.
  40. Foster, Jessica. For 37 years, tree farm has built tradition in FL Archived October 20, 2006, at the Wayback Machine, Forest Lake Times (Forest Lake, Minnesota), December 8, 2004. Retrieved September 4, 2007.
  41. Briody, Judy. Family traditions abound at Christmas tree farm Archived 2007-09-28 at the Wayback Machine, Farragut Press (Farragut, Tennessee), December 16, 2004. Retrieved September 4, 2007.
  42. McLeod, Gerald E. Day Trips, The Austin Chronicle (Austin, Texas), December 12, 2003. Retrieved September 6, 2007.
  43. Zigmond, Jessica. Christmas trees help hog business, Medill News Service, Northwestern University, August 17, 1999. Retrieved September 6, 2007.
  44. Scott, Julia. Tradition grows at 'perfect' Christmas tree farm, Oakland Tribune, December 8, 2006, via FindArticles. Retrieved September 6, 2007.
  45. British Christmas Tree Growers Association, official site. Retrieved September 6, 2007.
  46. About Us Archived 2007-09-28 at the Wayback Machine, National Christmas Tree Association, official site. Retrieved September 6, 2007.
  47. National Christmas Tree Association, "Real Christmas Trees are a Benefit to the Environment".
  48. Hickman, "Is it OK ... to get a Christmas tree?"
  49. Ellipsos Inc. "Life Cycle Assessment (LCA) of Christmas trees, A study ends the debate over which Christmas tree, natural or artificial, is most ecological Archived December 1, 2012, at the Wayback Machine", December 16, 2008; accessed online September 22, 2009.
  50. Koelling, Melvin R., et al. Christmas Tree Production in Michigan Archived November 14, 2006, at the Wayback Machine, Agricultural Experiment Station, Michigan State University, July 28, 1998. Retrieved September 3, 2007.
  51. Sidebottom, Frequently Asked Questions about Christmas Tree Farms and Pesticides.
  52. Wilson, Jon. Keep Christmas Trees Fresh and Safe Archived June 27, 2006, at the Wayback Machine, West Central Research & Extension Center, University of Nebraska, 4 December 2000. Retrieved 3 September 2007.
  53. Silviculture and Ecology Archived June 30, 2007, at the Wayback Machine, Department of Forest Resources, Oregon State University College of Forestry. Retrieved September 10, 2007.
  54. Current Research of 2004, Oregon State University College of Forestry. Retrieved September 10, 2007.
  55. Rost, Bob. OSU Extension helps growers improve Christmas tree genetics Archived September 14, 2006, at the Wayback Machine, (Press release), Oregon State University, News and Communications Services, December 9, 1996. Retrieved September 10, 2007.
  56. Christmas Tree Research and Forest Genetics Archived 2008-05-11 at the Wayback Machine, Agricultural Experiment Station, New Mexico State University, 2006. Retrieved September 10, 2007.
  57. "Christmas Tree Research and Extension Archived May 17, 2008, at the Wayback Machine", North Carolina State University, Department of Forestry and Environmental Resources, accessed April 16, 2007.
  58. Barth, Brian (19 December 2016). "Can Science Produce a Longer Lasting Christmas Tree?". Modern Farmer. Retrieved 25 December 2016.
  59. 29 CFR 780.208 - Forest and Christmas tree activities Archived September 27, 2007, at the Wayback Machine, Title 29, Chapter 5, Section 780.208, Code of Federal Regulations, United States Department of Labor. Retrieved September 10, 2007.
  60. Farm Service Agency Archived February 27, 2008, at the Wayback Machine, Agricultural Fact Book 1997 Archived October 17, 2007, at the Wayback Machine, Office of Communications, United States Department of Agriculture, 1997, p. 4. Retrieved September 10, 2007.
  61. Hoppe. Robert A. and Korb, Penni. Farm Numbers: Largest Growing Fastest Archived 2008-02-27 at the Wayback Machine, (PDF file), Agricultural Outlook, October 2002, pp. 24–27, Economic Research Service, United States Department of Agriculture. Retrieved September 7, 2007.
  62. "Net Farm Income Archived September 25, 2007, at the Wayback Machine, Agriculture Economic Statistics, Statistics Canada, May 2007. Retrieved 7 September 2007.
  63. HM Revenue & Customs, Nurseries and Market Gardens - definition.
  64. Forest Fresh Christmas Trees Archived September 15, 2007, at the Wayback Machine, Forest Service (Northern Ireland), United Kingdom Department of Agriculture and Rural Development. Retrieved September 10, 2007.
  65. Long, Tom. N.H. family's donation preserves Christmas tree tradition, The Boston Globe, 23 August 2007. Retrieved 4 September 2007.
  66. Chittenden, Jessica A. Commissioner urges consumers to buy New York Christmas trees Archived 2012-02-16 at the Wayback Machine, (Press release), New York State Department of Agriculture, 7 December 2006. Retrieved 4 September 2007.
  67. Go to a Christmas tree farm to relive, make, keep memories Archived 2007-09-29 at the Wayback Machine, Tennessee.gov, 13 November 2006. Retrieved 4 September 2007.
  68. Krug, Nick. Tradition clashes with economy, The Topeka Capital Journal (Topeka, Kansas), 2 December 2002, via FindArticles. Retrieved 4 September 2007.

References
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