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>On 19-Dec-0 Hi Dave and All Some woods - birch for example - if cut green, junked in stove length and left in a moist spot will develop fungus quite quickly. Well within a year. This will be on the cut ends of the stick. I suspect the fungus feed on the sap in the green wood but soon start a decaying action. Some of it is quite pretty - almost like coral that is seen in the water. Various shades of red or purple. I don't know if the spores of these fungus are air borne or prehaps are on or under the bark. The other day I removed the bark from a piece of spruce that was in the wood pile. A damp piece I might add - under was crawling with larvea - little wonder woodpeckers feed well on dead trees. Enjoy the winter Paul --- David & Alison Webster <dwebster@glinx.com> wrote: > Hi Peter & All, Dec 19, 2006 > That is a many sided question. There may be some > anti-fungal agents > present in some bark. Some barks for example are rot > resistant and used > for mulch or remain more or less intact for many > years in forest litter. > But the primary barrier to invasion via bark is > likely physical. The > outer bark is dead, as you supposed, and until the > outer bark starts to > erode has as many annual rings as there are on the > wood side. Only these > tissues are dense with almost no intercellular > spaces (except in > lenticels), walls are suberized or thickened and > firmly glued together, etc. > > In contrast, a common mode of entry for > wood-rotting fungi is > through wounds; broken tops, broken branches, torn > bark, insect holes > and pruning cuts. This invasion usually (always ?) > happens when the > trees are live and may eventually lead to death but > it is not uncommon > to see e.g. large hollow but partly living hardwood > trees. > > In many trees there is a collar at the base of > branches where the > wood of any one year of trunk and branch merge as a > contorted bulge or > collar. When pruning is done with hand powered saws > it is natural to > prune beyond this collar. But with chain saws, some > are tempted to do a > 'good' job and cut at the base of the collar rather > than beyond it. > This increases the chance of fungal invasion because > cutting at the base > of the collar exposes the wood of the trunk as much > as a deep notch would. > > An additional barrier to direct invasion of > intact above-ground bark > is moisture. Even dead bark on a standing dead tree > usually rots from > the inside out; the outside is dry too much of the > time. The outside of > bark, of a similar dead tree lying on the ground > such that the bark > remains moist will soon develop a flame of fungal > hyphae. > > I suspect that many fungal infections of > heartwood are via broken > roots, especially roots near the surface, but do not > know this for a fact. > > Yours truly, Dave Webster, Kentville > > Peter Payzant wrote: > > > Here's a question for the plant biologists: A dead > tree soon develops > > a garden of various kinds of fungi on its bark. > This doesn't happen to > > living trees, as far as I know (although lichens, > liverworts etc. do > > attach to them). > > > > > > > > The outer surface of the bark of a tree appears to > be made up of dead > > tissue. How is the tree able to fight off > infection by external fungi > > when it is more or less surrounded by dead > material? Is it perhaps a > > matter of attacking the fungal "roots" when they > penetrate the park to > > the living tissue? > > > > > > > > Peter Payzant > > > > > > > > > > > > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
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