Wood Destroying Fungi
Wood Destroying Fungi are a type of fungus that can cause significant damage to wood structures, leading to costly repairs and renovations. These fungi consume the natural cellulose found in wood, leaving behind dry rot and physical damage. The most common types of Wood Destroying Fungi are known as brown rot and white rot fungi. Brown rot fungi will naturally cause dry and brittle wood, while white rot fungi will leave the wood surface discolored or soft to the touch.
When left untreated, Wood Destroying Fungi can quickly spread from one area of a structure to another, causing massive amounts of structural damage and weakening the integrity of the building’s foundation. To avoid such issues, it is important for homeowners to be aware of this fungus and take steps towards preventing an infestation.
Fungi Are Not Plants
Because they lack chlorophyll, the essential chemical used by plants to produce their
own food. Fungi live as parasites and derive their nutrients from other sources.
In regards to Wood Destroying Fungi they survive on wood itself.
Two types of wood-decay fungi are found in structural wood:
Destructive
- Brown rot
- Water conducting rot
Nondestructive
- White pocket rot; Pecky Rot
- Surface and Sap-Stain Fungi
Origin Of Wood-Decay Fungi
Fungi reproduce Via spores. Spores are created by the fruiting body of the fungus and
can be considered microscopic seeds. Once they are released they travel by air and
attach to wood surfaces. The moisture content of the wood must reach 28% for the
spores to begin germination into a strand like structure which forms masses called
mycelia as they grow.The mycelia penetrates the the actual cell walls of the wood . Through the secretion of enzymes, the wood components are broken down into a usable food source. Left unchecked over time, the wood will loose its structural integrity.
Requirements For Fungal Survival
There are four essential elements needed for fungal survival in order to attack wood in
structures
- A food source (Wood)
- Moderate temperatures
- Oxygen
- Moisture
While moisture naturally occurs in wood, it is highest just after cutting and milling and
the levels gradually decrease over time as the wood dries.A normal moisture level is 6-
11% it is when the levels reach 28-32% that wood decay fungi can develop.
Moisture Sources
The three general sources of moisture include:
- Soil wood to ground contact
- Environment- such as ice dams in gutters, Plumbing leaks, poor or no vapor
barrier in crawl space areas or under slabs, Roof Leaks, Poor drainage of
ventilation in enclosed areas susceptible to environmental intrusion. - Water Vapor- Evaporation and condensation in poorly ventilated attics and crawl
spaces this can cause the exposed wood to become damp and collect enough
moisture to begin the growth of Fungi and support a conducive environment for
the Fungi to survive.
Destructive Wood-Decay Fungi
Two basic types of destructive wood-decaying fungi are found in structures. When they
are identified control measures are generally required. Bug Off Pest can Identify and
control these types of issues using chemical or mechanical control measures such as
vapor barriers and ventilation. Chemical treatments will stop the production and spread
of the spores.
- Cubical brown rot and White rot
- Water conducting rot (Poria)
Cubical Brown Rot. Brown rot occurs in wood that is exposed to an environment that
changes from dry to wet and back to dry in repetitive cycles. As the decay progresses
the wood shrinks, twists, cracks and breaks off into cubes.
White Rot. White rot infests wood that is exposed to continuous wet conditions. this
wood will take on a bleached appearance and the wood will become spongy and fibrous
breaking into stringy massed when probed. At times, a dark line representing the leading
edge of the fungus will appear around the edges of the bleached, decayed areas.
Water– conducting Rot. This is a specialized rot caused by conducting water from
remote sources sometimes feet away or even yards away and it infests sound, dry
wood.
This rot grows root like strands which extend from a moisture source in areas like
crawlspaces,water leaks or dirt filled porches up to the wood.
In some rare cases this rot has been traced from rotted wood in a home under the soil
to a water source up to 50 feet or further away.
The surface of the damaged wood takes on a wavy appearance and may still appear to
be structurally sound. If you probe the wood you will find rotted wood.
Water-conducting rot is sometimes called dry rot because it can attack dry wood
without an elevated moisture content. Damage can often be rapid and severe.
Non-Destructive Fungi
The non-destructive fungi include surface molds and mildew and sap-stain fungi. These
species use the sugars and starches in the wood cells as a food source but do not
damage the cellulose of the wood. These fungi just give the wood an unattractive
appearance.
The two types of non-destructive types of fungi attack wood in living trees. Once the
wood is milled, lumber the fungi dies but the evidence of the infestation may remain
visible on the surface of the wood. These rots are called White Pocket rot and Pecky
Rot.
Molds and Mildew
These fungi exist on the surface of wood but do not weaken the structural integrity on
the structure. They can be treated by simply brushing or sanding them. They grow in
dark and white patches on the surface within the top layers of the wood. These fungi are
usually early signs of moisture levels above 20% or higher.
White Pocket Rot
This is also known as pocket rot due to the appearance of dimples on the surface of the
infected wood. The decayed wood contains numerous spindle shaped pockets filled
with white, cottony fungus. This fungus only attacks live trees but the evidence will
remain after lumber is milled. No control is needed.
Pecky Rot
Pecky rot only attacks living trees, especially cedar and cypress. The infested areas are
recognizable from their channel-like cavities filled with soft, decayed wood. As with
white pocket rot, once the tree is milled the fungi dies but its evidence remains. In fact
consumers pay top dollar for this lumber that exhibits this fungus due to its rustic
appearance.
Bug Off Pest Moisture control services
Bug Off Pest offers services that can address some moisture issues in crawl spaces
such as foundation vent installations, Vapor Barrier installs and even encapsulation for
crawl spaces in some properties.
