[NAFEX] Dying tree

david.maxwell at dal.ca david.maxwell at dal.ca
Sun Jul 24 13:43:08 EDT 2011

I am most grateful to all those who have offerred advice and comments.  But I don't think we 
have this nailed down yet.  Michelle, I do not think it is "Brown Line Decline"  I sectioned the 
trunk starting at ground level.  At this point the wood is clean and white.  The bark is quite a 
bright orange, and i am a little uncertain whether this represents disease.  Starting about 8 
cm above ground level there is a little discoluration of the wood and an area of blackening of 
the bark.  As one proceeds up the trunk the discolouration in the wood becomes more and 
more prominent and obvious, giving a mottled appearance.  The bark at these levels has a 
clear area of necrosis, with a blackened appearance under the bark, which is separating. The 
maximum staining of the wood occurs between 24 and 30 cm., and above this, the bark is 
slightly darker in a small area, and only the heartwood is discoloured. The graft union is at 
about 40 cm and here there is only a minimal staining of the heartwood, but persistence of 
the small area of darker bark.  Above the graft union the Gideon cultivar looks absolutely 
clean, with green cambium and intact bark.  
My analysis is that whatever this is penetrated the bark at about 24 cm above ground level, 
and spread a little down, and up as far as the graft union, but not beyond it.  Judging by the 
staining of the wood, it has been present for a number of years.  (The tree was grafted in 
2001).  The interesting thing is the absence of external evidence of cankers or anything to 
suggest what was going on under the bark.

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