Pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accepts ...

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 PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...

as the

balsam woolly adelgid Balsam woolly adelgids (''Adelges piceae'') are small wingless insects that infest and kill firs, especially balsam fir and Fraser fir. They are an invasive species from Europe introduced to the United States around 1900. Because this species ...

and other adelgids.

Aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

s are another common insect pest. Christmas trees are also vulnerable to

fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

pathogens and their resultant illnesses such as root rot, and, in the U.S. state of

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

sudden oak death James Green aka "Sudden" is a fictional character created by an English author Oliver Strange in the early 1930s as the hero of a series, originally published by George Newnes Books Ltd, set in the American Wild West era. Oliver Strange died i ...

Douglas-fir The Douglas fir (''Pseudotsuga menziesii'') 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 va ...

trees in particular are vulnerable to infections from plant pathogens such as '' R. pseudotsugae''. Larger pests also pose a threat to Christmas tree plantations and harvests. Mammals such as

deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the re ...

gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They are ...

s and

ground squirrel Ground squirrels are members of the squirrel family of rodents ( Sciuridae), which generally live on or in the ground, rather than trees. The term is most often used for the medium-sized ground squirrels, as the larger ones are more commonly known ...

s are threats to Christmas tree crops because of the damage they cause to roots and buds. Certain species of birds are also considered pests, among these is the

pine grosbeak The pine grosbeak (''Pinicola enucleator'') is a large member of the true finch family, Fringillidae. It is the only species in the genus ''Pinicola''. It is found in coniferous woods across Alaska, the western mountains of the United States, Can ...

which feeds on conifer buds. Herbaceous

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

s, as well as

woody plant A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposite to herbaceous plants that die back to the ground until sp ...

s, also compete with Christmas tree crops for water and nutrients and thus must be controlled by farmers. There are several methods of control, including mowing, chemical herbicide use, and tilling.

Insects

The conifer species used and cultivated as Christmas trees are vulnerable to dozens of different pests, most of which cause cosmetic damage to the trees, important in the Christmas tree industry.
Christmas Tree Pest Manual
', Michigan State University Extension, ''United States Department of Agriculture'', 1997–1998

. Retrieved September 7, 2007. The

(''Adelges picae'') are small soft-bodied insects which attack the

Fraser fir The Fraser fir (''Abies fraseri'') is a species of fir native to the Appalachian Mountains of the Southeastern United States. ''Abies fraseri'' is closely related to ''Abies balsamea'' (balsam fir), of which it has occasionally been treated a ...

. The insects appear as white, woolly spots on the tree and are fatal to the fir if left untreated. The woolly adelgid was native to central Europe where it affected the

silver fir Silver fir is a common name for several trees and may refer to: *''Abies alba ''Abies alba'', the European silver fir or silver fir, is a fir native to the mountains of Europe, from the Pyrenees north to Normandy, east to the Alps and the Car ...

; it was introduced to the United States, where it has no known native predators, before 1900.Sidebottom, Jill R
Frequently Asked Questions about Christmas Tree Farms and Pesticides
, Mountain Horticultural Crops Research & Extension Center, ''North Carolina State University'', October 30, 2006. Retrieved September 3, 2007. Balsam twig aphids (''Mindarus abietnus'') are another type of tree pest which affects fir and spruce trees in the spring. The

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

s can cause stunted growth in trees with heavy infestations rendering badly damaged trees unsellable. Other species of adelgids also infest fir trees, those include the pine bark adelgid, the Cooley spruce gall adelgid (''

Adelges cooleyi The gall adelgid (''Adelges cooleyi'') is an adelgid species that produces galls in spruce trees. They infect the new buds of native spruce trees in the foothills of the Rocky Mountains in the spring. They also attack blue spruce to a lesser de ...

''), and the eastern spruce gall adelgid (''Adelges abietis''). Another serious pest are bagworms. These pests can defoliate a tree completely if present in large enough numbers. Additionally, the damage caused by the silk of bagworms can last years.Day, Eric
Insect Pests of Christmas Trees slides
, Insect Identification Laboratory, Department of Entomology, ''Virginia Tech'', January 2002. Retrieved September 3, 2007. Invasive insect species such as the pine shoot beetle and the

spongy moth ''Lymantria dispar'', also known as the gypsy moth or the spongy moth, is a species of moth in the family Erebidae. ''Lymantria dispar'' is subdivided into several subspecies, with subspecies such as ''L. d. dispar'' and ''L. d. japonica'' bei ...

also threaten Christmas tree crops.Division of Communications: Untitled story
, ''Outdoor Indiana'', November/December 2006, Indiana Department of Natural Resources. Retrieved September 4, 2007. Spongy moth infestations in Canada required restrictions and requirements to be placed upon Christmas tree growers with plantations in "spongy moth regulated areas". The restrictions and requirements included ongoing site monitoring, active moth eradication by the grower, accurate record keeping, and government directed moth eradication programs. Failure to abide by the rules could result in revocation of the "approved grower" status from the Canadian Food Inspection Agency.Gypsy Moth Control Program for Christmas Tree Growers
Export requirements for cut Christmas trees to Mexico: D-95-11, ''Canadian Food Inspection Agency'', August 2, 2007. Retrieved September 7, 2007. The major types of conifers cultivated,

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accepts ...

s, true firs, and spruce trees, are all affected by some types of insect pests. Douglas-firs are most vulnerable to the Cooley spruce gall adelgid. The true firs are most susceptible to insects such as the balsam gall midge (''Paradiplosis tumifex''), and the balsam twig aphid. Species of spruce trees face assault from insects such as the

white pine weevil ''Pissodes strobi'', known as the white pine weevil or Engelmann spruce weevil, is the primary weevil attacking and destroying white pines. It was described in 1817 by William Dandridge Peck, professor of natural history and botany at Harvard ...

(''Pissodes strobi''), Cooley spruce gall adelgid, and the pine needle scale (''Chionaspis pinifoliae''). The final category of Christmas trees, pines, are commonly susceptible to insect infestation and damage from the pine root collar weevil ('' Hylobius radicis''), Zimmerman pine moth ('' Dioryctria zimmermani''), pine needle scale, and white pine weevil.McCullough, Deborah G. and Koelling, Melvin R
Integrated Pest Management in Christmas Tree Production
, Integrated Pest Management World Textbook, ''University of Minnesota'', September 20, 1996. Retrieved September 7, 2007.

Fungal pests and diseases

Christmas trees are also vulnerable to large scale infestations from various fungal

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

s. In 2002 concern in the

U.S. Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

arose over the spread of a relatively new fungal disease called annosus root rot ('' Heterobasidion annosum'' or '' Fomes annosus''). The disease is spread by airborne fungal spores and was first discovered in Northwest Christmas tree farms in 1983.Schmitz, John
Fungal disease of true firs attacking Christmas trees
, ''The Capital Press'', June 28, 2002, via Washington State University. Retrieved September 3, 2007. The plant pathogen, ''

Phytophthora ramorum ''Phytophthora ramorum'' is the oomycete (a type of protist) plant pathogen known to cause the disease sudden oak death (SOD). The disease kills oak and other species of trees and has had devastating effects on the oak populations in California ...

'', which causes "sudden oak death" (SOD), is a fungus-like protist which was identified in the early 1990s. By 2002, sudden oak death had been reported along the California coast and the

Oregon Coast The Oregon Coast is a coastal region of the U.S. state of Oregon. It is bordered by the Pacific Ocean to its west and the Oregon Coast Range to the east, and stretches approximately from the California state border in the south to the Columbia ...

, and two species of conifer were identified as hosts of the pathogen, Douglas fir and

coast redwood ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995:606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal ...

. Between 2003 and 2005 ''P. ramorum'' was detected in Douglas fir,

grand fir ''Abies grandis'' (grand fir, giant fir, lowland white fir, great silver fir, western white fir, Vancouver fir, or Oregon fir) is a fir native to the Pacific Northwest and Northern California of North America, occurring at altitudes of sea leve ...

white fir ''Abies concolor'', the white fir, is a coniferous tree in the pine family Pinaceae. This tree is native to the mountains of western North America, including the Cascade Range and southern Rocky Mountains, and into the isolated mountain ranges ...

and California red fir on Christmas trees in

Santa Clara County Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259, as of the 2020 census. Santa Clara County and neighboring San Benito County together f ...

.A Christmas Tree Grower's Guide to Sudden Oak Death (Phytophthora ramorum)
, ( PDF file), College of Natural Resources, ''University of California, Berkeley'', November 20, 2006. Retrieved September 3, 2007.

Camellia ''Camellia'' (pronounced or ) is a genus of flowering plants in the family Theaceae. They are found in eastern and southern Asia, from the Himalayas east to Japan and Indonesia. There are more than 220 described species, with some controv ...

s imported from California to

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

in 2003 and early 2004 caused a significant SOD scare in the horticultural and Christmas tree industries. The detection of ''P. ramorum'' led to plant recalls in Canada, and a series of steps meant to quarantine the disease before it spread.Sudden Oak Death (SOD) - Phytophthora ramorum
, ''City of Victoria'' (British Columbia), Parks, Recreation & Community Development: Parks Division. Retrieved September 11, 2007. The 2003–2004 SOD scare extended to

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

and

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

nurseries and farms. Douglas-firs are vulnerable to the two plant pathogens that cause Rhabdocline needle cast, '' Rhabdocline pseudotsugae'', and '' Rhabdocline weirii''. ''R. weirii'' affects only Douglas-fir trees.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. The pathogen often makes Douglas fir trees unsalable as Christmas trees and affects the Christmas tree farming industry.Rhabodocline Needlecast (''Rhabdocline weirii'')
Department of Plant Pathology, ''Cornell University''. Retrieved September 7, 2007. Douglas firs are also affected by ''Phaeocryptopus gaumanni'' which causes Swiss needle cast. Red band needle blight is a fungal disease which affects coniferous trees, particularly pine, with a worldwide distribution. The disease is caused by the fungi '' Dothistroma septosporum''. Since the late 1990s its appearance in the United Kingdom has increased, among the most affected species is

Corsican pine ''Pinus nigra'', the Austrian pine or black pine, is a moderately variable species of pine, occurring across Southern Europe from the Iberian Peninsula to the eastern Mediterranean, on the Anatolian peninsula of Turkey, Corsica and Cyprus, as wel ...

and the disease has been a significant problem in

Thetford Forest Thetford Forest is the largest lowland pine forest in Britain and is located in a region straddling the north of Suffolk and the south of Norfolk in England. It covers over in the form of a Site of Special Scientific Interest. History The ...

.Brown, Anna, et al
Red Band Needle Blight of Pine
, ( PDF file), Information Note, ''United Kingdom Forestry Commission'', September 2003. Retrieved September 11, 2007. Though the disease spread rapidly during September 2007 Christmas tree growers remained confident that Christmas tree crops would be unaffected.Xmas tree growers play down 'crisis'
''Watton and Swaffham Times'' (

Thetford Thetford is a market town and civil parish in the Breckland District of Norfolk, England. It is on the A11 road between Norwich and London, just east of Thetford Forest. The civil parish, covering an area of , in 2015 had a population of 24, ...

), September 5, 2007. Retrieved September 11, 2007.

Mammals

Small mammals can be significant pests to reforestation site and Christmas tree plantations.

Vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...

s, or meadow mice, can cause damage to conifer plantation seedlings. The potential for vole infestation is highest when the land has ample grass and undergrowth coverage; which is often found in plantations and sites that are on old

pasture Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep, or sw ...

s that already have a large vole population.Duddles, R.E. and DeCalesta, D.S
Controlling Vole Damage to Conifer Seedlings
( PDF file), ''The Woodland Workbook'', Oregon State University Extension Service, ''Oregon State University'', August 1992. Retrieved September 7, 2007. In the

(

pocket gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They are ...

) damage to conifer seedlings occurs over thousands of acres, causing significant economic loss for the region. Gophers have a tendency to damage root systems as well as strip bark off the base of seedlings.DeCalesta, D.S., et al
Controlling Pocket Gopher Damage to Conifer Seedlings
( PDF file), Oregon State University Extension Service, ''Oregon State University'', May 2003. Retrieved September 7, 2007. Other mammal pests to Christmas tree farms include, porcupine, rabbit,

, and

thirteen-lined ground squirrel The thirteen-lined ground squirrel (''Ictidomys tridecemlineatus''), also known as the striped gopher, leopard ground squirrel, squinney, (formerly known as the leopard-spermophile in the age of Audubon), is a ground squirrel that is widely dis ...

.
Christmas Tree Pest Manual
', Michigan State University Extension, ''United States Department of Agriculture'', 1997–1998

. Retrieved September 7, 2007.

Other pests

Other types of pests which affect Christmas tree production include arachnids such as the spruce spider mites (''Oligonychus ununguis''), and rust mites (''Nalepella''). In addition some species of birds are considered pests by Christmas tree farmers, examples include the

(''Pinicola enucleator'') and the yellow-bellied sapsucker (''Sphrapicus varius''). The pine grosbeak feeds on buds on conifers, including Christmas trees, which stunts tree growth, causes abnormal formation, and thins the foliage. The pine grosbeak, as a pest, generally affects Scots pine but also affects eastern white and red pine as well as spruce trees.''Christmas Tree Pest Manual''
Shoot/Branch Injury
, Yellow-bellied Sapsucker, Michigan State University Extension, ''United States Department of Agriculture'', 1997–1998

. Retrieved September 7, 2007. The yellow-bellied sapsucker, as a Christmas tree pest, is hosted by Scots and Austrian pine trees. The sapsuckers peck holes in sapling bark causing sap to bleed out: potentially killing the trees and allowing insects and pathogens to enter.''Christmas Tree Pest Manual'',

, Yellow-bellied Sapsucker, Michigan State University Extension, ''United States Department of Agriculture'', 1997–1998

. Retrieved September 7, 2007.

Weeds

The types of plants considered

s in Christmas tree cultivation vary from region to region. Regardless of the types of plants, from herbaceous weeds to

woody plants A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposite to herbaceous plants that die back to the ground until sp ...

, weeds are considered a pest to Christmas tree farms for several reasons.

Seedling 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 (embryonic root), the hypocotyl (embryo ...

s are vulnerable to the competition for water and nutrients presented by weed infestations, however, even established trees can be out competed by weed growth. Some specific weeds cause more serious problems, the

bracken fern Bracken (''Pteridium'') is a genus of large, coarse ferns in the family (biology), family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produ ...

can increase disease in

fir tree Firs (''Abies'') are a genus of 48–56 species of evergreen coniferous trees in the family Pinaceae. They are found on mountains throughout much of North and Central America, Europe, Asia, and North Africa. The genus is most closely related t ...

s, and employee morale and efficiency are decreased when weeds such as

poison oak Poison oak refers to two plant species in the genus ''Toxicodendron,'' both of which can cause skin irritation: *''Toxicodendron diversilobum'' or Western poison oak, found in western North America *''Toxicodendron pubescens ''Toxicodendron pub ...

Canada thistle ''Cirsium arvense'' is a perennial species of flowering plant in the family Asteraceae, native throughout Europe and western Asia, northern Africa and widely introduced elsewhere.Joint Nature Conservation Committee''Cirsium arvense'' The standa ...

and wild blackberries infest plantations. In addition, excessive weed growth can provide cover for wildlife, such as deer, gopher and field mice, which can have damaging effects on Christmas tree crops.William R.D. and Al-Khatib, K
Managing Weeds and Vegetation in Christmas Trees
,
PDF version
), Pacific Northwest Extension, ''Oregon State University'', August 1995. Retrieved September 7, 2007.

Control

Weed control

One of the primary methods of weed control in the Christmas tree farming industry is through the use of chemical herbicides. The use of herbicides and other pesticides is one of the key reasons Christmas tree farms have met with opposition from environmentalists.Koelling, Melvin R., et al
Christmas Tree Production in Michigan
, Agricultural Experiment Station, ''Michigan State University'', July 28, 1998. Retrieved September 3, 2007.Hickman, Leo

''Guardian'' (UK), December 6, 2005. Retrieved September 3, 2007. In applying herbicides growers must determine proper spray volume and timing.Johnson, James E. and Torbert, John L

, Introduction to Growing Christmas Trees in Virginia, Virginia Cooperative Extension, ''Virginia Tech'', March 1997. Retrieved September 7, 2007. There are different types of herbicides that are used to control different types of weeds, they fall into two different categories. Soil applied herbicides combat germinating seedlings, and some offer control of newly established plants. Uniform application over the soil followed by moisture are required for soil applied herbicides to work effectively. Foilar-active herbicides control weed growth of already established, actively growing plants. Application of foliar-active herbicides requires farmers to avoid contact with the conifers. Non chemical methods of

weed control Weed control is a type of pest control, which attempts to stop or reduce growth of weeds, especially noxious weeds, with the aim of reducing their competition with desired flora and fauna including domesticated plants and livestock, and in n ...

include rotary mowing and

flail A flail is an agriculture, agricultural tool used for threshing, the process of separating cereal, grains from their husks. It is usually made from two or more large sticks attached by a short chain; one stick is held and swung, causing the othe ...

ing. Rotary mowing is designed to cut unwanted vegetation 5–7 cm (2–3 inches) above the surface of the soil while flailing cuts the vegetation near the soil surface. This method of weed control reduced the loss of soil moisture and nutrients by reducing the size and the growth of the weeds. The act of cultivation disturbs weed growth, especially in the seedling phase, as well by disrupting the soil around roots. Another method of combating problem weeds, in areas that have not responded to other control methods, is the practice of spot

hoeing A hoe is an ancient and versatile agricultural and horticultural hand tool used to shape soil, remove weeds, clear soil, and harvest root crops. Shaping the soil includes piling soil around the base of plants (hilling), digging narrow furrow ...

or tilling.

Other pest control

References

{{Christmas tree cultivation Pest insects Pests and weeds