Christmas tree pests and weeds
Encyclopedia
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
and fir
Fir
Firs are a genus of 48–55 species of evergreen conifers in the family Pinaceae. They are found through much of North and Central America, Europe, Asia, and North Africa, occurring in mountains over most of the range...
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
Balsam woolly adelgid
Balsam woolly adelgids 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....
and other adelgids. Aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...
s are another common insect pest. Christmas tree
Christmas tree
The Christmas tree is a decorated evergreen coniferous tree, real or artificial, and a tradition associated with the celebration of Christmas. The tradition of decorating an evergreen tree at Christmas started in Livonia and Germany in the 16th century...
s are also vulnerable to fungal
Fungus
A fungus is a member of a large 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, Fungi, which is separate from plants, animals, and bacteria...
pathogens and their resultant illnesses such as root rot
Root rot
Root rot is a condition found in both indoor and outdoor plants, although more common in indoor plants with poor drainage. As the name states, the roots of the plant rot. Usually, this is a result of overwatering. In houseplants, it is a very common problem, and is slightly less common in outdoor...
, and, in the U.S. state of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, sudden oak death
Sudden oak death
Sudden Oak Death is the common name of a disease caused by the oomycete plant pathogen Phytophthora ramorum. The disease kills oak and other species of tree and has had devastating effects on the oak populations in California and Oregon as well as also being present in Europe...
. Douglas-fir
Douglas-fir
Douglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia...
trees in particular are vulnerable to infections from plant pathogens such as R. pseudotsugae
Rhabdocline pseudotsugae
Rhabdocline pseudotsugae is a fungal plant pathogen. The pathogen, along with Rhabdocline weirii causes Rhabdocline needlecast; R. weirii only affects Douglas-fir trees. The disease causes the needles of the tree to discolor and eventually fall from the tree. It was originally common to the Rocky...
.
Larger pests also pose a threat to Christmas tree plantations and harvests. Mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s such as deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
, gopher
Gopher (animal)
The term gopher as it is commonly used does not relate to any one species, but is a generic term used to describe any of several small burrowing rodents endemic to North America, including the pocket gopher , also called true gophers, and the ground squirrel , including Richardson's ground squirrel...
s and ground squirrel
Ground squirrel
The ground squirrels are members of the squirrel family of rodents 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 as marmots or prairie dogs, while the smaller and less...
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
Pine Grosbeak
left|thumb|Adult femaleThe Pine Grosbeak is a large member of the true finch family, Fringillidae. It is found in coniferous woods across Alaska, the western mountains of the United States, Canada, and in subarctic Fennoscandia and Siberia...
which feeds on conifer buds. Herbaceous weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
s, as well as woody plant
Woody plant
A woody plant is a plant that uses wood as its structural tissue. These are typically perennial plants whose stems and larger roots are reinforced with wood produced adjacent to the vascular tissues. The main stem, larger branches, and roots of these plants are usually covered by a layer of...
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
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
use, and tilling.
Insects
Balsam woolly adelgid
Balsam woolly adelgids 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....
(Adelges picae) are small soft-bodied insects which attack the Fraser Fir
Fraser Fir
Abies fraseri is a species of fir native to the mountains of the eastern United States. It is closely related to Abies balsamea , of which it has occasionally been treated as a subspecies or a variety Abies fraseri (Fraser fir) is a species of fir native to the mountains of the eastern United...
. The insects appear as white, woolly spots on the tree and are fatal to the fir if left untreated. The woolly adeligid was native to central Europe where it affected the silver fir
Silver Fir
Abies alba, commonly known as the European silver fir, is a fir native to the mountains of Europe, from the Pyrenees north to Normandy, east to the Alps and the Carpathians, and south to southern Italy and northern Serbia.-Description:...
; it was introduced to the United States, where it has no known native predators, before 1900.
Balsam twig aphids (Mindarus abietnus) are another type of tree pest which affects fir and spruce trees in the spring. The aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...
s can cause stunted growth in trees with heavy infestations rendering badly damaged trees unsellable. Other species of adelgid
Gall Adelgid
Gall adelgid refers to adelgid species that produce galls in spruce trees, conifer species. Such galls can be produced by an infection by Adelges cooleyi , a species of aphid-like woolly adelgids ...
s also infest fir trees, those include the pine bark adelgid, the Cooley spruce gall adelgid (Adelges cooleyi), and the Eastern spruce gall adelgid. 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.
Invasive insect species such as the pine shoot beetle and the gypsy moth
Gypsy moth
The gypsy moth, Lymantria dispar, is a moth in the family Lymantriidae of Eurasian origin. Originally ranging from Europe to Asia, it was introduced to North America in the late 1860s and has been expanding its range ever since...
also threaten Christmas tree crops. Gypsy moth infestations in Canada required restrictions and requirements to be placed upon Christmas tree growers with plantations in "gypsy 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.
The major types of conifers cultivated, pine
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
s, Douglas-fir
Douglas-fir
Douglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia...
s, true fir
Fir
Firs are a genus of 48–55 species of evergreen conifers in the family Pinaceae. They are found through much of North and Central America, Europe, Asia, and North Africa, occurring in mountains over most of the range...
s, and spruce
Spruce
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 regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...
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
Cecidomyiidae
Cecidomyiidae is a family of flies known as gall midges or gall gnats. As the name implies, the larvae of most gall midges feed within plant tissue, creating abnormal plant growths called galls.These are very fragile small insects usually only 2–3 mm in length and many are less than...
(Paradiplosis tumifex), and the Balsam twig aphid. Species of spruce trees face assault from insects such as the White pine weevil (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
Hylobius
Hylobius is a genus of true weevils . Several Hylobius species are major pests of coniferous trees.-Species:Species include:*Hylobius abietis Linnaeus, 1758 — pine weevil...
radicis), Zimmerman pine moth (Dioryctria zimmermani), pine needle scale , and white pine weevil.
Fungal pests and diseases
Christmas trees are also vulnerable to large scale infestations from various fungal pathogenPathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
s. In 2002 concern in the U.S. Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
arose over the spread of a relatively new fungal disease called annosus root rot (Heterobasidion annosum
Heterobasidion annosum
Heterobasidion annosum is a basidiomycete fungus in the family Bondarzewiaceae. It is considered to be the most economically important forest pathogen in the Northern Hemisphere. Heterobasidion annosum is widespread in forests in the United States and is responsible for the loss of one billion U.S....
or Fomes annosus). The disease is spread by airborne fungal spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s and was first discovered in Northwest Christmas tree farms in 1983.
The plant pathogen, Phytophthora ramorum, which causes sudden oak death
Sudden oak death
Sudden Oak Death is the common name of a disease caused by the oomycete plant pathogen Phytophthora ramorum. The disease kills oak and other species of tree and has had devastating effects on the oak populations in California and Oregon as well as also being present in Europe...
(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
Coastal California
Coastal California refers to the coastal regions of the US state of California. The term is not primarily geographical as it also describes an area distinguished by sociological, economical and political attributes...
and the Oregon coast
Oregon Coast
The Oregon Coast is a region of the U.S. state of Oregon. It runs generally north-south along the Pacific Ocean, forming the western border of the state; the region is bounded to the east by the Oregon Coast Range. The Oregon Coast stretches approximately from the Columbia River in the north to...
, and two species of conifer were identified as hosts of the pathogen, Douglas fir and coast redwood. Between 2003 and 2005 P. ramorum was detected in Douglas fir, grand fir
Grand Fir
Abies grandis is a fir native to the Pacific Northwest and Northern California of North America, occurring at altitudes of sea level to 1,800 m...
, white fir
White Fir
White Fir is a fir native to the mountains of western North America, occurring at altitudes of 900-3,400 m. It is a medium to large evergreen coniferous tree growing to 25–60 m tall and with a trunk diameter of up to 2 m . It is popular as an ornamental landscaping tree and as a Christmas Tree...
and California red fir on Christmas trees in Santa Clara County
Santa Clara County, California
Santa Clara County is a county located at the southern end of the San Francisco Bay Area in the U.S. state of California. As of 2010 it had a population of 1,781,642. The county seat is San Jose. The highly urbanized Santa Clara Valley within Santa Clara County is also known as Silicon Valley...
. Camellia
Camellia
Camellia, the camellias, is a genus of flowering plants in the family Theaceae. They are found in eastern and southern Asia, from the Himalaya east to Korea and Indonesia. There are 100–250 described species, with some controversy over the exact number...
s imported from California to British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
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
Product recall
A product recall is a request to return to the maker a batch or an entire production run of a product, usually due to the discovery of safety issues. The recall is an effort to limit liability for corporate negligence and to improve or avoid damage to publicity...
in Canada, and a series of steps meant to quarantine the disease before it spread. The 2003–2004 SOD scare extended to Washington and Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
nurseries and farms.
Douglas-firs are vulnerable to the two plant pathogens that cause Rhabdocline needlecast, Rhabdocline pseudotsugae
Rhabdocline pseudotsugae
Rhabdocline pseudotsugae is a fungal plant pathogen. The pathogen, along with Rhabdocline weirii causes Rhabdocline needlecast; R. weirii only affects Douglas-fir trees. The disease causes the needles of the tree to discolor and eventually fall from the tree. It was originally common to the Rocky...
, and Rhabdocline weirii
Rhabdocline weirii
Rhabdocline weirii is a fungal plant pathogen. The pathogen, along with Rhabdocline pseudotsugae, causes Rhabdocline needlecast; R. weirii only affects Douglas-fir trees. The disease causes the needles of the tree to discolor and eventually fall from the tree...
. R. weirii affects only Douglas-fir trees. The pathogen often makes Douglas fir trees unsalable as Christmas trees and affects the Christmas tree farming industry. Douglas firs are also affected by Phaeocryptopus gaumanni which causes Swiss needlecast.
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 Mycosphaerella pini, also known as Dothistroma pini (formerly D. septospora). Since the late 1990s its appearance in the United Kingdom has increased, among the most affected species is Corsican Pine
European Black Pine
Pinus nigra, the European Black Pine, is a moderately variable species of pine, occurring across southern Mediterranean Europe from Spain to the Crimea, in Asia Minor and on Cyprus, and in the high mountains of the Maghreb in North Africa....
and the disease has been a significant problem in Thetford Forest
Thetford Forest
Thetford Forest is the largest lowland pine forest in Britain, Thetford Forest Park is located in a region straddling the north of Suffolk and the south of Norfolk in England...
. Though the disease spread rapidly during September 2007 Christmas tree growers remained confident that Christmas tree crops would be unaffected.
Mammals
Small mammals can be significant pests to reforestation site and Christmas tree plantations. VoleVole
A vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...
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
Pasture 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 swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...
s that already have a large vole population. In the U.S. Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
, gopher
Gopher (animal)
The term gopher as it is commonly used does not relate to any one species, but is a generic term used to describe any of several small burrowing rodents endemic to North America, including the pocket gopher , also called true gophers, and the ground squirrel , including Richardson's ground squirrel...
(pocket gopher
Pocket gopher
The pocket gophers are burrowing rodents of the family Geomyidae. These are the "true" gophers, though several ground squirrels of the family Sciuridae are often called gophers as well...
) 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. Other mammal pests to Christmas tree farms include, porcupine
Porcupine
Porcupines are rodents with a coat of sharp spines, or quills, that defend or camouflage them from predators. They are indigenous to the Americas, southern Asia, and Africa. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about long, with...
, rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
, deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
, and thirteen-lined ground squirrel
Thirteen-lined ground squirrel
The thirteen-lined ground squirrel , also known as the striped gopher, leopard ground squirrel, squinney, and as the leopard-spermophile in Audubon’s day, is a ground squirrel....
.
Other pests
Spider mite
Spider mites are members of the Acari family Tetranychidae, which includes about 1,200 species. They generally live on the under sides of leaves of plants, where they may spin protective silk webs, and they can cause damage by puncturing the plant cells to feed...
(Oligonychus ununguis), and rust mites (Nalepella).
In addition some species of birds are considered pests by Christmas tree farmers, examples include the Pine Grosbeak
Pine Grosbeak
left|thumb|Adult femaleThe Pine Grosbeak is a large member of the true finch family, Fringillidae. It is found in coniferous woods across Alaska, the western mountains of the United States, Canada, and in subarctic Fennoscandia and Siberia...
(Pinicola enucleator) and the Yellow-bellied Sapsucker
Yellow-bellied Sapsucker
The Yellow-bellied Sapsucker is a medium-sized woodpecker found in North America, Central America and the Caribbean.-Taxonomy:...
(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. 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.
Weeds
The types of plants considered weedWeed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
s in Christmas tree cultivation vary from region to region. Regardless of the types of plants, from herbaceous weeds to woody plants, weeds are considered a pest to Christmas tree farms for several reasons. Seedling
Seedling
thumb|Monocot and dicot seedlingsA seedling is a young plant 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...
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 can increase disease in fir trees, and employee morale and efficiency are decreased when weeds such as poison oak
Poison oak
Poison oak may refer to* Toxicodendron diversilobum, grows on West Coast of North America* Toxicodendron pubescens, grows in the Eastern United Statesdamnnnnn tissss is terribleee...
, Canada thistle and wild blackberries
Blackberry
The blackberry is an edible fruit produced by any of several species in the Rubus genus of the Rosaceae family. The fruit is not a true berry; botanically it is termed an aggregate fruit, composed of small drupelets. The plants typically have biennial canes and perennial roots. Blackberries and...
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.
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 herbicideHerbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
s and other pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s is one of the key reasons Christmas tree farms have met with opposition from environmentalists. In applying herbicides growers must determine proper spray volume and timing. 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
Weed control is the botanical component of pest control, using physical and chemical methods to stop weeds from reaching a mature stage of growth when they could be harmful to domesticated plants and livestock...
include rotary mowing and flail
Flail
A flail is an agricultural implement for threshing.Several tools operate similarly to the agricultural implement and are also called flails:...
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
Hoe (tool)
A hoe is an ancient and versatile agricultural tool used to move small amounts of soil. Common goals include weed control by agitating the surface of the soil around plants, piling soil around the base of plants , creating narrow furrows and shallow trenches for planting seeds and bulbs, to chop...
or tilling.