More Decay

Question 1

What things effect the rate of decay?

Answer 1

• Antagonism
• Toxins
• 02
• N
• Host defences

Question 2

What are some aspects of antagonism that effect rate of decay?

Answer 2

-Heartwood contains endophytic fungi that are antagonistic to decay fungi. e.g.. Ascocoryne sarcoides in B, H and S.

Question 3

What are some aspects of toxins that effect rate of decay?

Answer 3

• Trees release toxins when parenchyma die

- Heartwood contains toxins

Question 4

What are some toxins?

Answer 4

• Phenolics

- Thujapliacin

Question 5

Why does cedar have more rot than other trees despite its defences?

Answer 5

• 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.

Question 6

What aspects of 02 effect rate of decay?

Answer 6

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

Question 7

What trees utilize wet wood as a defines mechanism?

Answer 7

Cottonwood
Aspen
Willow
Elm
Hemlock and balsam
-trees with low or no chemical defences

Question 8

What aspects of nitrogen effect rate of decay?

what tree is an example of this?

Answer 8

• 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)

Question 9

Aside from host defences, which factors effect rate of decay?

Answer 9

• Antagonism
• Toxins
• O2
• N

Question 10

What are the host defences that effect rate of decay?

Answer 10

• Bark
• Callous over
• wounded sapwood
• resin
• CODIT

Question 11

What are barks defences?

Answer 11

• dead bark: toxins

- live bark: cork cambium

Question 12

What is a trees defence mechanism to seal off a wound?

Answer 12

Callous over

• to block future invasion
• block 02 and limit decay of new infection

Question 13

What does wounded sapwood do to defend against infection?

Answer 13

• kamikaze reaction just behind wound will form a barrier that isolates the wounded area.

Question 14

list some qualities of wound barriers? (4)

Answer 14

• impervious to gases and liquids (and fungi)
• can contain toxins
• saucer shaped in shallow wound
• pipe shaped in deep wound that hits heartwood

Question 15

What is resin’s role in tree defence?

Answer 15

• resin pumped to wounds
• has toxic compounds
• attempts to seal off wounded area

Question 16

What does CODIT stand for?

Answer 16

Compartmentalization Of Decay In Trees

Question 17

What does CODIT imply? What trees do it?

Answer 17

• Happens in hardwoods
• Special ring of wood (impervious wall) loaded with tannins laid down after scar.
• If complete = shape of tree