Difference between revisions of "Sudden Oak Death (SOD)"

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Sudden oak death (SOD) is a non-native forest disease that is believe to have originated from Asia and spread via international nursery trade. <ref>[https://www.nps.gov/redw/learn/nature/sod.htm US National Park Service]</ref> The name of the disease is rooted in its initial discovery in 1995 when researchers in Marin County, California observed widespread rapid oak mortality.<ref>[https://www.nps.gov/pore/learn/nature/diseases_sod.htm US National Park Service]</ref><ref>[https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/mtpmctn4719.pdf (USDA) Department of Agriculture (US). 2003. Sudden Oak Death (SOD). UPlant Materials Technical Note. Montana: USDA. Available from: Technical Note Plant Materials MT-44]</ref> Researchers later determined that SOD results from infection by ''Phytophthora ramorum'', a type of water mold responsible for causing [[Ramorum Blight]]. <ref>[http://www.suddenoakdeath.org/about-sudden-oak-death/pathogen/ California Oak Mortality Task Force]</ref>  
 
Sudden oak death (SOD) is a non-native forest disease that is believe to have originated from Asia and spread via international nursery trade. <ref>[https://www.nps.gov/redw/learn/nature/sod.htm US National Park Service]</ref> The name of the disease is rooted in its initial discovery in 1995 when researchers in Marin County, California observed widespread rapid oak mortality.<ref>[https://www.nps.gov/pore/learn/nature/diseases_sod.htm US National Park Service]</ref><ref>[https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/mtpmctn4719.pdf (USDA) Department of Agriculture (US). 2003. Sudden Oak Death (SOD). UPlant Materials Technical Note. Montana: USDA. Available from: Technical Note Plant Materials MT-44]</ref> Researchers later determined that SOD results from infection by ''Phytophthora ramorum'', a type of water mold responsible for causing [[Ramorum Blight]]. <ref>[http://www.suddenoakdeath.org/about-sudden-oak-death/pathogen/ California Oak Mortality Task Force]</ref>  
  
Oak species vary in their susceptibility to ''Phytophthora ramorum'' infection. Tanoak (''Lithocarpus densiforus'') and coast live oak (''Quercus agrifolia'') have poor resistance to infection and experience high mortality rates.<ref>[http://cisr.ucr.edu/sudden_oak_death.html UCR]</ref> Over 1 million trees have died due to SOD in Northern and Central California. <ref>[http://cisr.ucr.edu/sudden_oak_death.html UCR]</ref>
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Oak species vary in their susceptibility to ''P. ramorum'' infection. Tanoak (''Lithocarpus densiforus'') and coast live oak (''Quercus agrifolia'') have poor resistance to infection and experience high mortality rates.<ref>[http://cisr.ucr.edu/sudden_oak_death.html UCR]</ref> Over 1 million trees have died due to SOD in Northern and Central California. <ref>[http://cisr.ucr.edu/sudden_oak_death.html UCR]</ref>
  
 
== Symptoms ==
 
== Symptoms ==

Revision as of 01:46, 30 March 2017

Sudden Oak Death in Marin County. Image: [1]

This page discusses sudden oak death (SOD), an oak tree disease caused by the plant pathogen (Phytophthora ramorum).

In addition to SOD, Phytophthora ramorum also causes Ramorum Blight. Phytophthora ramorum was first documented in Central California in the mid-1990s, and has since caused severe mortality of several oak tree species and most notably tanbark oak (Notholithocarpus densiflorus). In 2014, Phytophthora ramorum was estimated to extend from Santa Barbara in California to Curry County in Oregon [1]. The disease has been found worldwide. It is speculated that the disease spread world-wide via the nursery industry. Currently, restrictions exist on the movement of nursery plants, firewood, and soil to minimize the spread of the disease.

The disease was named in the mid-1990s when oak and tanbark oak trees suddenly and simultaneously exhibited signs of distress and subsequently died [2]. The severe die-back of the species gained public and political attention, and subsequently the California Oak Mortality Task Force was formed to identify the cause of the oak deaths. Today the California Oak Mortality Task Force coordinates research, monitoring, management and education of SOD.

Phytophthora ramorum affects many plant species. Phytophthora ramorum can infect and cause mortality in the following species: coast live oak, California black oak, Shreve oak, and canyon live oak, as well as tanoak trees. Phytophthora ramorum can causes twig and foliar diseases in species such as California Bay laurel, Douglas-fir, and coast redwood. These species are often hosts of pathogen, primarily responsible for the pathogen's dispersal, but themselves do not die from the disease. Implications of SOD spread include loss of habitat, loss of food sources for wildlife, increase in exposed soils, and changes in the frequency and intensity of wildfires.

Phytophthora ramorum thrives in cool, wet climates [3]. Phytophthora ramorum is a water-borne pathogen that disperses via fog, wind, water droplets, streams and splashing.

Background

Sudden oak death (SOD) is a non-native forest disease that is believe to have originated from Asia and spread via international nursery trade. [4] The name of the disease is rooted in its initial discovery in 1995 when researchers in Marin County, California observed widespread rapid oak mortality.[5][6] Researchers later determined that SOD results from infection by Phytophthora ramorum, a type of water mold responsible for causing Ramorum Blight. [7]

Oak species vary in their susceptibility to P. ramorum infection. Tanoak (Lithocarpus densiforus) and coast live oak (Quercus agrifolia) have poor resistance to infection and experience high mortality rates.[8] Over 1 million trees have died due to SOD in Northern and Central California. [9]

Symptoms

Foliar Blight

Leaves of tanoak affected by SOD. Image: [2]
Twig of an oak tree affected by SOD and displaying signs of lesions and a Shepherd's Crook. Image: [3]

Foliar Blight and branch die-back are some of the early indicators of infection. One of the earliest indicators are a "Shepherd's Crook", or wilting of apical shoots. Other foliage-related symptoms include brown blotches on leaves, rapid browning leaves throughout the crown, tip droop and die-back, and branch die-back caused by branch cankers.[10][11] These symptoms, particularly the browning of the crown, occur 2 to 4 weeks after infection. However, trees typically do not die immediately after these symptoms appear. The latency period between foliar blight and death is around two years.[12]

Trunk cankers and "bleeding"

Known Phytophthora ramorum Hosts

Prevalence in Central California

Impacts

Ecology

Commerce

Humans

Management

Distribution and efficacy of remediation

Laws

Current Research

References

  1. Citation needed
  2. Garbelotto M. and Hayden KJ. 2012. Sudden Oak Death: Interactions of the Exotic Oomycete Phytophthora ramorum with Naïve North American Hosts. Eukaryotic Cell: 11(11):1313.
  3. California Oak Mortality Task Force
  4. US National Park Service
  5. US National Park Service
  6. (USDA) Department of Agriculture (US). 2003. Sudden Oak Death (SOD). UPlant Materials Technical Note. Montana: USDA. Available from: Technical Note Plant Materials MT-44
  7. California Oak Mortality Task Force
  8. UCR
  9. UCR
  10. UC BERKELEY FOREST PATHOLOGY AND MYCOLOGY LAB
  11. Sentinel Plant Network
  12. California Oak Mortality Task Force

Links

Disclaimer

This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of [CSUMB], its staff, or students.