Editing Chestnut blight (section)

==Symptoms==
[[File:Chestnut blight on cut tree in Adams County Ohio.jpg|thumb|left|A chestnut tree that has been felled, with blight on its inner bark and trunk]]
The fungus enters through wounds on susceptible trees and grows in and beneath the bark, eventually killing the [[Cork cambium|cambium]] all the way around the twig, branch, or trunk.<ref>Anagnostakis SL (2000) Revitalization of the Majestic Chestnut: Chestnut Blight Disease.</ref> The first symptom of ''C. parasitica'' infection is a small orange-brown area on the tree bark. A sunken [[canker]] then forms as the [[mycelium|mycelial]] fan spreads under the bark. As the [[hypha]]e spread, they produce several toxic compounds, the most notable of which is [[oxalic acid]]. This acid lowers the pH of the infected tissue from around the normal 5.5 to approximately 2.8, which is toxic to cambium cells. The canker eventually girdles the tree, killing everything above it. Distinctive yellow [[tendril]]s (cirrus) of [[Conidium|conidia]] can be seen extruding in wet weather.<ref>Crop Protection Compendium 2005 Edition. ''Cryphonectria parasitica'' (blight of chestnut). CAB International, Wallingford, UK.</ref>