More Decay Flashcards
What things effect the rate of decay?
- Antagonism
- Toxins
- 02
- N
- Host defences
What are some aspects of antagonism that effect rate of decay?
-Heartwood contains endophytic fungi that are antagonistic to decay fungi. e.g.. Ascocoryne sarcoides in B, H and S.
What are some aspects of toxins that effect rate of decay?
- Trees release toxins when parenchyma die
- Heartwood contains toxins
What are some toxins?
- Phenolics
- Thujapliacin
Why does cedar have more rot than other trees despite its defences?
- Heartwood begins as straw coloured
- Sporothrix fungus detox thujapliacin changing colour to pinkish.
- K. thujina detox phenols changing colour to brown
- Further invasion of others remove the remaining toxins and then decay fungi move in.
What aspects of 02 effect rate of decay?
Some trees instead of toxins will saturate themselves with water to remove the oxygen required by decay.
- wetwood saturated with water
- anaerobic (no O2 available for decay)
- also N fixing bacteria uses 02 (high pH and methane)
- scar drains water, leading to decay
What trees utilize wet wood as a defines mechanism?
Cottonwood Aspen Willow Elm Hemlock and balsam -trees with low or no chemical defences
What aspects of nitrogen effect rate of decay?
what tree is an example of this?
- most wood low in N and fungi need N to grow
- fungi recycle their own hypha
- set up conditions for N fixing bacteria
- Alder is good example (high N and fast decay)
Aside from host defences, which factors effect rate of decay?
- Antagonism
- Toxins
- O2
- N
What are the host defences that effect rate of decay?
- Bark
- Callous over
- wounded sapwood
- resin
- CODIT
What are barks defences?
- dead bark: toxins
- live bark: cork cambium
What is a trees defence mechanism to seal off a wound?
Callous over
- to block future invasion
- block 02 and limit decay of new infection
What does wounded sapwood do to defend against infection?
- kamikaze reaction just behind wound will form a barrier that isolates the wounded area.
list some qualities of wound barriers? (4)
- impervious to gases and liquids (and fungi)
- can contain toxins
- saucer shaped in shallow wound
- pipe shaped in deep wound that hits heartwood
What is resin’s role in tree defence?
- resin pumped to wounds
- has toxic compounds
- attempts to seal off wounded area
