Cottage Q&A
QUESTIONOur young white pine, which had seemed healthy and vigorous, died quickly last summer. There were no outward signs of damage. When we cut it down, I noticed this black discoloration in the trunk. Is this the cause of the tree's demise? Do we have to worry about all the other white pines on our property?
ANSWER
The blackish discoloration is almost certainly one of the so-called stain fungi, probably introduced into the wood by a bark or ambrosia beetle. The beetles (and their larvae) cause damage by feeding on the inner bark, or cambium layer, of the tree. The stain fungus contributes to the damage by plugging up the phloem, the system of conduits that convey sugars and starches (made in the leaves) back to the rest of the tree.
That said, forest pathologist John McLaughlin, with the Ontario Forest Research Institute in Sault Ste. Marie, doubts these pests are the primary problem. These beetles are consummate opportunists, able to identify stressed trees and single them out for attack. He can't tell from the picture (below) what would have caused this tree's initial decline and left it vulnerable - but if the rest of your white pines remain uninjured and growing in a suitable environment, there's no reason to suppose that they will suffer the same fate.
* Published in the June 2005 issue of Cottage Life
