Wood decaying fungi, their features and related information.

1. General Features of White Rot and Brown Rot
Fungi

2. Introduction
 Plant matter is constantly under attack by fungi, insects,
bacteria, marine borers and the weather.
 It is estimated that roughly 1/10 of the forest products
generated each year are destroyed.
 Wood decay or wood rot is caused by fungi – organisms that
live on other organic matter such as wood.
 While this can be bad, without these processes we would be
buried in a sea of old dead plant matter.
2

3. Occurrence
 Decay of timber occurs only when wood is allowed to remain
permanently or regularly damp.
 Decay is described as either wet rot or dry rot; although both
can occur together in damp wood.
 Can develop on susceptible wood if the moisture content of the
wood remains above about 22% regularly for prolonged
periods.
 Develop from minute airborne spores which germinate if they
land on a suitable substrate such as damp wood.
 Produce thread-like hyphae, which collectively form a
mycelium.
 The hyphae making up the mycelium penetrate the wood,
breaking down the wood cell walls and feeding on them.
 Mycelium produces a fruit-body; this releases spores to the
atmosphere, completing the life cycle.
3

4. Types and Forms
 White rot - all components removed
 Brown rot - primarily carbohydrates lost, lignin mostly remains
 Soft rot - carbohydrates preferred, but some lignin lost too
 Slash rot - decay of dead material left behind after logging
Positions
 Heart rot - decay in the stem that develops primarily in the
heartwood or inner wood of living trees
 Sap rot - saprobic decays that develop in the sapwood
 Butt and root rot - decay primarily in the roots or at the base of
a tree heart rot - decay in the stem that develops primarily in the
heartwood or inner wood of living trees
4

5. Types and Forms (Cont’d)
5

6. White Rot Fungi
 This group of organisms is known as white rot because of their ability
to degrade lignin. Can delete up to 100% of Timber weight.
 The decaying wood looks white.
 Cellulose and hemicelluloses are also degraded.
 Generally decay occur from lumen outwards.
 White rot fungi typically decay hardwoods
 They will decay softwoods but hardwoods are their food of choice.
6

7. White Rot Fungi (Cont’d)
 Largest number of species belong to Basidiomycotina
 Xyariaceous and Diatrypacsous also numerous.
7

8. Brown Rot Fungi
 With brown rot fungi, cellulose and hemicelluloses are degraded with
only limited lignin degradation. Can delete up to 65% of timber weight.
 Decayed wood is brown and crumbly.
 Brown rot fungi typically decay softwoods.
 Attack starts at the cell lumen and works outwards.
 Cellulose is rapidly degraded.
8

9. Brown Rot Fungi (Cont’d)
 Most species belong to Basidiomycotina.
9

10. Features of white and brown rot
10

11. Defense Against Decay
 Wall thickening
 Phenolic chemistry
 Wound periderm
 Programmed cell death
 Outer physical/chemical barrier
 Bark/cuticle
 H2O, O2, N limits
 Heartwood chemistry
 Extractives
11

12. Benefits
12
Woody says,
Fungi are great!
I wouldn’t have
a home without
them!

13. THANK YOU
For Your Attention!