Christmas tree pests and weeds

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An entomologist checks Scots pine for pine shoot beetles at a Christmas tree farm near East Lansing, Michigan. Christmas tree farm East Lansing MI check for pine shoot beetles.jpg
An entomologist checks Scots pine for pine shoot beetles at a Christmas tree farm near East Lansing, Michigan.

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 .

Contents

Larger pests also pose a threat to Christmas tree plantations and harvests. Mammals such as deer, gophers and ground squirrels 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 which feeds on conifer buds. Herbaceous weeds, as well as woody plants, 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

An adult balsam woolly adelgid, a major pest in the Christmas tree industry Balsam woolly adelgid.gif
An adult balsam woolly adelgid, a major pest in the Christmas tree industry

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. [1] [2] The balsam woolly adelgid (Adelges picae) are small soft-bodied insects which attack the Fraser fir. 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; it was introduced to the United States, where it has no known native predators, before 1900. [1]

Balsam twig aphids (Mindarus abietnus) are another type of tree pest which affects fir and spruce trees in the spring. The aphids can cause stunted growth in trees with heavy infestations rendering badly damaged trees unsellable. [1] Other species of adelgids also infest fir trees, those include the pine bark adelgid, the Cooley spruce gall adelgid ( Adelges cooleyi ), and the eastern spruce gall adelgid (Adelges abietis). [3] 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. [3]

Invasive insect species such as the pine shoot beetle and the spongy moth also threaten Christmas tree crops. [4] Spongy moth infestations in Canada required restrictions and requirements to be placed upon Christmas tree growers with plantations in "spongy moth regulated areas". [5] The restrictions and requirements included ongoing site monitoring, active moth eradication by the grower, accurate record keeping, and government directed moth eradication programs. [5] Failure to abide by the rules could result in revocation of the "approved grower" status from the Canadian Food Inspection Agency. [5]

The major types of conifers cultivated, pines, Douglas-firs, true firs, and spruce trees, are all affected by some types of insect pests. [6] 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), 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. [6]

Fungal pests and diseases

A hillside devastated by sudden oak death includes species of conifer. The disease has been found at California Christmas tree farms. Sudden oak death IMG 0223.JPG
A hillside devastated by sudden oak death includes species of conifer. The disease has been found at California Christmas tree farms.

Christmas trees are also vulnerable to large scale infestations from various fungal pathogens. In 2002 concern in the U.S. Pacific Northwest arose over the spread of a relatively new fungal disease called annosus root rot ( Heterobasidion annosum or Fomes annosus ). [7] The disease is spread by airborne fungal spores and was first discovered in Northwest Christmas tree farms in 1983. [7]

The plant pathogen, Phytophthora ramorum , which causes "sudden oak death" (SOD), is a fungus-like protist which was identified in the early 1990s. [8] By 2002, sudden oak death had been reported along the California coast and the Oregon Coast, and two species of conifer were identified as hosts of the pathogen, Douglas fir and coast redwood. [8] Between 2003 and 2005 P. ramorum was detected in Douglas fir, grand fir, white fir and California red fir on Christmas trees in Santa Clara County. [8] Camellias imported from California to British Columbia 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. [9] The 2003–2004 SOD scare extended to Washington and Oregon nurseries and farms. [9]

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. [10] [11] The pathogen often makes Douglas fir trees unsalable as Christmas trees and affects the Christmas tree farming industry. [10] Douglas firs are also affected by Phaeocryptopus gaumanni which causes Swiss needle cast. [6]

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 and the disease has been a significant problem in Thetford Forest. [12] Though the disease spread rapidly during September 2007 Christmas tree growers remained confident that Christmas tree crops would be unaffected. [13]

Mammals

Small mammals can be significant pests to reforestation site and Christmas tree plantations. Voles, or meadow mice, can cause damage to conifer plantation seedlings. [14] 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 pastures that already have a large vole population. [14] In the U.S. Pacific Northwest, gopher (pocket gopher) 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. [15] Other mammal pests to Christmas tree farms include, porcupine, rabbit, deer, and thirteen-lined ground squirrel. [16]

Other pests

A young pine grosbeak. The bird is regarded as a pest by Christmas tree growers. Pinicola enucleator5.jpg
A young pine grosbeak. The bird is regarded as a pest by Christmas tree growers.

Other types of pests which affect Christmas tree production include arachnids such as the spruce spider mites (Oligonychus ununguis), and rust mites (Nalepella). [1]

In addition some species of birds are considered pests by Christmas tree farmers, examples include the pine grosbeak (Pinicola enucleator) and the yellow-bellied sapsucker (Sphrapicus varius). [16] 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. [17] 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. [18]

Weeds

The types of plants considered weeds 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. Seedlings are vulnerable to the competition for water and nutrients presented by weed infestations, however, even established trees can be out competed by weed growth. [19] 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, Canada thistle and wild blackberries infest plantations. [19] 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. [19]

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. [20] [21] In applying herbicides growers must determine proper spray volume and timing. [22] 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. [19] Foilar-active herbicides control weed growth of already established, actively growing plants. [19] Application of foliar-active herbicides requires farmers to avoid contact with the conifers.

Non chemical methods of weed control include rotary mowing and flailing. 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. [19] This method of weed control reduced the loss of soil moisture and nutrients by reducing the size and the growth of the weeds. [19] The act of cultivation disturbs weed growth, especially in the seedling phase, as well by disrupting the soil around roots. [19] Another method of combating problem weeds, in areas that have not responded to other control methods, is the practice of spot hoeing or tilling. [19]

Other pest control

See also

Related Research Articles

<span class="mw-page-title-main">Douglas fir</span> Species of tree

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.

<span class="mw-page-title-main">Conifer</span> Group of cone-bearing seed plants

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. The division Pinophyta contains seven families, 60 to 65 genera, and more than 600 living species.

<span class="mw-page-title-main">Spruce</span> Genus of evergreen, coniferous tree

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.

<span class="mw-page-title-main">Weed control</span> Botanical component of pest control for plants

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 natural settings preventing non native species competing with native species.

<i>Phytophthora ramorum</i> Species of single-celled organism

Phytophthora ramorum is the oomycete 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 and Oregon, as well as being present in Europe. Symptoms include bleeding cankers on the tree's trunk and dieback of the foliage, in many cases leading to the death of the tree.

<span class="mw-page-title-main">Bark beetle</span> Subfamily of beetles

A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the term "bark beetle" refers to the fact that many species feed in the inner bark (phloem) layer of trees, the subfamily also has many species with other lifestyles, including some that bore into wood, feed in fruit and seeds, or tunnel into herbaceous plants. Well-known species are members of the type genus Scolytus, namely the European elm bark beetle S. multistriatus and the large elm bark beetle S. scolytus, which like the American elm bark beetle Hylurgopinus rufipes, transmit Dutch elm disease fungi (Ophiostoma). The mountain pine beetle Dendroctonus ponderosae, southern pine beetle Dendroctonus frontalis, and their near relatives are major pests of conifer forests in North America. A similarly aggressive species in Europe is the spruce ips Ips typographus. A tiny bark beetle, the coffee berry borer, Hypothenemus hampei is a major pest on coffee plantations around the world.

<span class="mw-page-title-main">Blue spruce</span> Species of tree

The blue spruce, also commonly known as green spruce, Colorado spruce, or Colorado blue spruce, is a species of spruce tree. It is native to North America, and is found in USDA growing zones 1 through 7. It is found naturally in Arizona, Colorado, Idaho, New Mexico, Utah and Wyoming. It has been widely introduced elsewhere and is used as an ornamental tree in many places far beyond its native range. The blue spruce has blue-green colored needles and is a coniferous tree.

<span class="mw-page-title-main">Diplodia tip blight</span> Fungal disease of conifers

Diplodia tip blight, also known as Sphaeropsis blight, is a widespread disease affecting conifers caused by an opportunistic fungal pathogen, Diplodia sapinea. It is found in “both hemispheres between the latitudes 30° and 50° north and south". The diseases symptoms include: damping off and collar rot of seedlings, stem canker, root disease, and, most commonly, shoot blight. These symptoms have caused significant economic loss to nurseries and pine plantations. In a nursery in the north-central United States, losses of 35% have been reported. Shoot blight and eventual die back can cause a reduction of marketable volume in timber by 63%. Infection of terminal shoots can result in dead-top which significantly limits the usable length of the tree trunk. The presence of the pathogen in concert with severe weather conditions can lead to extreme loss. Following a severe hailstorm in South Africa, nearly 5,000 acres of pine plantation were infected with Diplodia tip blight. It was necessary to prematurely harvest large swaths of the plantations resulting in a loss of 45%. Areas that were not harvested prematurely still suffered an average timber loss of 11%.

Forest integrated pest management or Forest IPM is the practice of monitoring and managing pest and environmental information with pest control methods to prevent pest damage to forests and forest habitats by the most economical means.

The gall adelgid 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 degree. The insects complete two generations within the year. They require two different trees for its life cycle, the second being the Rocky Mountain Douglas-fir. They may also attack Sitka, Engelmann, or white spruce. The many different species of adelgids produce different galls on different spruce species.

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. The pathogen often makes Douglas-fir trees unsalable as Christmas trees and affects the Christmas tree farming industry.

<span class="mw-page-title-main">Adelgidae</span> Family of true bugs

The Adelgidae are a small family of the Hemiptera closely related to the aphids, and often included in the Aphidoidea with the Phylloxeridae or placed within the superfamily Phylloxeroidea as a sister of the Aphidoidea within the infraorder Aphidomorpha. The family is composed of species associated with pine, spruce, or other conifers, known respectively as "pine aphids" or "spruce aphids". This family includes the former family Chermesidae, or "Chermidae", the name of which was declared invalid by the ICZN in 1955. There is still considerable debate as to the number of genera within the family, and the classification is still unstable and inconsistent among competing authors.

<span class="mw-page-title-main">Christmas tree cultivation</span> Cultivation of trees used as Christmas trees

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

<span class="mw-page-title-main">Wilding conifer</span> Invasive trees in New Zealand

Wilding conifers, also known as wilding pines, are invasive trees in the high country of New Zealand. Millions of dollars are spent on controlling their spread.

<span class="mw-page-title-main">Balsam woolly adelgid</span> Insect that attacks fir trees

The balsam woolly adelgid is small wingless insect that infests and kills firs. In their native Europe they are a minor parasite on silver fir and Sicilian fir, but they have become a threat especially to balsam fir and Fraser fir after they were introduced to the United States around the beginning of the 20th century. Because this species is not native to North America, the Fraser fir has not evolved any type of defense against it.

<i>Fusarium circinatum</i> Species of fungus

Fusarium circinatum is a fungal plant pathogen that causes the serious disease pitch canker on pine trees and Douglas firs. The most common hosts of the pathogen include slash pine, loblolly pine, Monterey pine, Mexican weeping pine, and Douglas fir. Like other Fusarium species in the phylum Ascomycota, it is the asexual reproductive state of the fungus and has a teleomorph, Gibberella circinata.

<span class="mw-page-title-main">Pineapple gall adelgid</span> Species of true bug

The pineapple gall adelgid is a species of conifer-feeding insect that forms pineapple-shaped plant galls on its host species, commonly Norway and Sitka spruce. The adelgids are pear-shaped, soft-bodied green insects with long antennae, closely related to the aphid. Adelges lays up to one hundred eggs at a time, one on each needle. Adelges abietis is one of the most common species; synonyms are A. gallarum-abietis, Chermes abietis and Sacciphantes abietis.

<i>Hylastes ater</i> Species of beetle

Hylastes ater is a species of beetle in the family Curculionidae, the true weevils. It is a bark beetle, a member of the subfamily Scolytinae. Its common name is the black pine bark beetle. It is native to Europe and parts of Asia, including China and Korea. It is known as an introduced species in many other regions, including Australia, New Zealand, the Americas, and South Africa. It is a pest of pines and other trees, and it is widespread in areas where pine trees are cultivated. The species "is an important threat to the biosecurity of all forested countries."

<span class="mw-page-title-main">Forest disturbance by invasive insects and diseases in the United States</span>

Species which are not native to a forest ecosystem can act as an agent of disturbance, changing forest dynamics as they invade and spread. Invasive insects and pathogens (diseases) are introduced to the United States through international trade, and spread through means of natural and human-dispersal. Invasive insects and pathogens are a serious threat to many forests in the United States and have decimated populations of several tree species, including American chestnut, American elm, eastern hemlock, whitebark pine, and the native ash species. The loss of these tree species is typically rapid with both short and long-term impacts to the forest ecosystem.

<i>Nalepella</i> Genus of mites infesting conifers

Nalepella, the rust mites, is a genus of very small Trombidiform mites in the family Phytoptidae. They are commonly found on a variety of conifers, including hemlock, spruce, balsam fir, and pine. They sometimes infest Christmas trees in nurseries. Nalepella mites are vagrants, meaning they circulate around the tree; females overwinter in bark cracks. Infested spruce emit a characteristic odour.

References

  1. 1 2 3 4 Sidebottom, Jill R. Frequently Asked Questions about Christmas Tree Farms and Pesticides Archived 2004-06-19 at the Wayback Machine , Mountain Horticultural Crops Research & Extension Center, North Carolina State University, October 30, 2006. Retrieved September 3, 2007.
  2. ↑ Christmas Tree Pest Manual , Michigan State University Extension, United States Department of Agriculture, 1997–1998, Table of Contents Archived 2007-08-09 at the Wayback Machine . Retrieved September 7, 2007.
  3. 1 2 Day, Eric. Insect Pests of Christmas Trees slides Archived August 19, 2007, at the Wayback Machine , Insect Identification Laboratory, Department of Entomology, Virginia Tech, January 2002. Retrieved September 3, 2007.
  4. ↑ 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.
  5. 1 2 3 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.
  6. 1 2 3 McCullough, Deborah G. and Koelling, Melvin R. Integrated Pest Management in Christmas Tree Production Archived 2007-10-01 at the Wayback Machine , Integrated Pest Management World Textbook, University of Minnesota, September 20, 1996. Retrieved September 7, 2007.
  7. 1 2 Schmitz, John. Fungal disease of true firs attacking Christmas trees Archived January 10, 2008, at the Wayback Machine , The Capital Press, June 28, 2002, via Washington State University. Retrieved September 3, 2007.
  8. 1 2 3 A Christmas Tree Grower's Guide to Sudden Oak Death (Phytophthora ramorum) Archived 2008-02-27 at the Wayback Machine , (PDF file), College of Natural Resources, University of California, Berkeley, November 20, 2006. Retrieved September 3, 2007.
  9. 1 2 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 September 11, 2007.
  10. 1 2 Rhabodocline Needlecast (Rhabdocline weirii), Department of Plant Pathology, Cornell University. Retrieved September 7, 2007. Archived June 11, 2007, at the Wayback Machine
  11. ↑ 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.[ dead link ]
  12. ↑ Brown, Anna, et al. Red Band Needle Blight of Pine Archived 2008-08-04 at the Wayback Machine , (PDF file), Information Note, United Kingdom Forestry Commission, September 2003. Retrieved September 11, 2007.
  13. ↑ Xmas tree growers play down 'crisis' [ permanent dead link ], Watton and Swaffham Times (Thetford), September 5, 2007. Retrieved September 11, 2007.
  14. 1 2 Duddles, R.E. and DeCalesta, D.S. Controlling Vole Damage to Conifer Seedlings Archived 2008-07-05 at the Wayback Machine (PDF file), The Woodland Workbook, Oregon State University Extension Service, Oregon State University, August 1992. Retrieved September 7, 2007.
  15. ↑ DeCalesta, D.S., et al. Controlling Pocket Gopher Damage to Conifer Seedlings Archived 2008-07-04 at the Wayback Machine (PDF file), Oregon State University Extension Service, Oregon State University, May 2003. Retrieved September 7, 2007.
  16. 1 2 Christmas Tree Pest Manual , Michigan State University Extension, United States Department of Agriculture, 1997–1998, Index A Archived 2007-08-09 at the Wayback Machine . Retrieved September 7, 2007.
  17. ↑ Christmas Tree Pest Manual, Shoot/Branch Injury Archived 2007-01-03 at the Wayback Machine , Yellow-bellied Sapsucker, Michigan State University Extension, United States Department of Agriculture, 1997–1998, Table of Contents Archived 2007-08-09 at the Wayback Machine . Retrieved September 7, 2007.
  18. ↑ Christmas Tree Pest Manual, "Dead Tree and Root Stem Injury", Yellow-bellied Sapsucker, Michigan State University Extension, United States Department of Agriculture, 1997–1998, Table of Contents Archived 2007-08-09 at the Wayback Machine . Retrieved September 7, 2007.
  19. 1 2 3 4 5 6 7 8 9 William R.D. and Al-Khatib, K. Managing Weeds and Vegetation in Christmas Trees Archived 2006-09-02 at the Wayback Machine , (PDF version Archived 2006-09-04 at the Wayback Machine ), Pacific Northwest Extension, Oregon State University, August 1995. Retrieved September 7, 2007.
  20. ↑ 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.
  21. ↑ Hickman, Leo. Is it OK . . . to get a Christmas tree?, Guardian (UK), December 6, 2005. Retrieved September 3, 2007.
  22. ↑ Johnson, James E. and Torbert, John L. Christmas tree production Archived 2007-08-13 at the Wayback Machine , Introduction to Growing Christmas Trees in Virginia, Virginia Cooperative Extension, Virginia Tech, March 1997. Retrieved September 7, 2007.
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