Thousand Canker Disease
by Aahan Kotian
The Culprit
Thousand Canker Disease is caused by a beetle known as the Walnut Twig Beetle or Pityophthorus Juglandis which harbors a fungus known as Geosmithia morbida. No one knows the origin of the fungus however the beetle originates from Arizona.
Description
- The beetle is slightly bigger than the eye on a penny which is around 2 mm and a dark shade of reddish brown.
- When this beetle mates and lays its eggs into the wood beneath the bark of the host tree the fungus it leaves behind kills the wood and leaves dark brown cankers where it burrows and light yellow patches on the tissue that prevents the storage as well as production of sugars to sustain the tree.
- Some external signs of infection include yellowing as well as loss of the leaves on the branches and twigs.
- The average time for the infected tree to die is three years but some can live up to a decade with TCD.
TCD in Canada
Ecological Niche
Cause for Population Decline of Black Walnut Trees
- Due to shipping of walnut wood that has been poorly inspected of insects the beetles have become more numerous and have started to appear East of their original home range.
- The authorities have not found a way to effectively eradicate the beetles before they inhabit the trees and infect it with Geosmithia.
Range of Walnut Twig Beetles
Population size of Walnut Twig Beetles
Ecological Impact
What is being done to combat expansion of the walnut twig beetle?
Tree afflicted with TCD
Range of Black Walnut Tree
Range of Walnut Twig Beetle
Sources
http://invasiveinsects.ca/tcd/tcd.html
https://www.walnutcouncil.org/.../Questions-and-Answers-Revision-11-9-09.doc
http://extension.colostate.edu/docs/pubs/insect/qa.pdf
http://www.thousandcankers.com/frequently-asked-questions.php
http://forestinvasives.ca/Meet-the-Species/Pathogens/Thousand-Canker-Disease
http://canadiantreetours.org/species-pages/Black_walnut.html
http://www.invadingspecies.com/invaders/pathogens/thousand-canker-disease/
http://www.thousandcankers.com/media/images/TCD_Confirmed_State_Map_8_2014.png
http://ncforestservice.gov/forest_health/forest_health_thousandcankers.htm
http://www.ijraf.org/pdf/v2-i9/5.pdf
http://www.aces.edu/ucf/BlackwalnutThousandCankerDisease.php
http://bspm.agsci.colostate.edu/files/2013/03/TCD-Pest-Alert-Revision-for-2012.pdf