Decay is the process of disintegration by which sound wood is decomposed. A pathogen is the actual agent of decomposition, usually a fungus or other micro-organism. Tree decay fungi reduce lumber recovery, lower lumber and chip quality and can cause dangerous conditions in recreation areas. Tree decay may lead to early tree mortality from a variety of factors, such as breakage, blowdown or predisposition to other forest health factors. Decay fungi also play an important role in creating gaps in forest canopies and play a lead role in nutrient cycling, species succession, biodiversity and the creation of wildlife habitat. The biology of decay fungi is such that harvesting, regeneration and stand management activities can affect the competitive behavior of decay pathogens in ecosystems.

An important principle of forest management is that the role of decay fungi in each ecosystem must be understood. Forest management objectives and prescriptions should then be set in light of the constraints of pathogen biology.

While there are a myriad of decay pathogens that may have implications for stand prescriptions, they can be separated into four broad categories:

• white rots in conifers
• brown rots in conifers
• white pocket rots in conifers
• broadleaf decays.

Do not consider the standards set forth in this guidebook as definitive or absolute; nor should they be used to form the basis for any punitive action. This guidebook offers very general recommendations for dealing with tree decays in the prescription. The intent is to provide the user with several concepts and estimates of the probable outcome of prescribed activities. Hopefully, these recommendations will give the user a reasonable understanding of the action and effect of decays, to help achieve the desired objectives of the prescription.

This guidebook provides:

• the necessary tools for managing decay pathogens (e.g., identification aids, hazard and risk assessment procedures, decay dynamics and impact information)
• a background to decay pathogen management
• guidance in creating treatment regimes to achieve the management objectives for the prescription
• recommended criteria of acceptable tree damage for lowering the risks due to decay fungi.

A third group is composed of fungi such as Fomitopsis pinicola that apparently have no special substrate requirements. These species may attack either uncolonized or previously colonized wound surfaces on living trees or act as true saprophytes on dead material. With few exceptions, all wound parasites complete their life cycle on dead material.

Major wood decay fungi in B.C.

While this list may appear formidable at first, general trends can be seen among most of these fungi. This guide will help you to effectively prescribe for and manage these decays in forest operations.

Signs and symptoms of some common wood decay fungi

Table 2. Summary of factors used to identify common decay fungi in B.C.

Fungus species	Conk color a) top, b) bottom	Fruiting body characteristics	Wood decay characteristics	Means of entry
Phaeolus schweinitzii	a) red-orange to brown b) brown	shelf or cluster on ground	red-brown cubical butt rot, irridescent sheen	roots, basal trunk wounds, fire scars
Fomitopsis pinicola	a) grey to dark brown,     red margin b) white	thick shelf-like, perennial	light brown stain, brown cubical rot with white mycelial felts	mechanical, insect and fire- caused wounds
Fomitopsis officinalis	a) white or dark b) white	hoof or cylindric with chalky surface	brown cubical with thick mycelial felts	wounds, fire scars
Phellinus weirii (cedar form)	a) brown-grey b) cream	shelf-like conk, perennial	laminated white heart rot	root contacts
Postia sericeomollis	creamy white	thin crust-like form on end of logs or on slash	yellow-brown stain, brown cubical butt rot in pockets	basal trunk wounds
Stereum sanguinolentum	a) brown-grey b) brown, blood-red     if bruised	small thin bracket shelf, common on slash and log ends	red-brown heartwood stain, brown stringy rot	trunk wounds, freshly exposed wood
Echinodontium tinctorium	a) dark grey b) light grey, spiny	thick hoof-shaped bracket, rough concentric rings	light brown water- soaked stain, brown stringy rot	small branch stubs (spores dormant until tree injured)
Pholiota spp.	scaly, sticky yellow-brown mushroom	gilled mushroom, occurs in clusters	dark brown streaks forming holes or pockets in heartwood	basal wounds, fire scars, frost cracks
Heterobasidion annosum	creamy porous lower surface	perennial crust-like found on upturned tree butt and roots	yellow- to red-brown stain, white spongy rot with black flecks	fresh basal trunk wounds, infected root contact
Armillaria sinapina	honey-brown mushroom	mushroom, black shoestring-like rhizomorphs and white mycelial fans under bark	light brown water soaked stain, light yellow-white spongy to stringy butt rot, black zone lines	root contacts with infected trees
Phellinus pini	a) dark grey b) brown, angled pores	shelf-like, perennial, velvety margin	red stain, often in rings, white pocket rot	branch stubs
Ganoderma applanatum	a) grey or tan b) white, brown when     touched	large, shelf- like perennial, concentric rings	bleached and ringed by dark brown stain, white spongy rot	mostly on old trees but can enter trunk wounds
Phellinus igniarius	a) black or grey, rough     deeply zoned b) brown	hoof-shaped, perennial, concentric rings on upper surface	yellow-white heartwood stain surrounded by green-brown zone, soft yellow-white rot with black zone lines	knots, branch stubs and wounds
Phellinus tremulae	a) black or grey,     rough, zoned b) brown	hoof-shaped, perennial, concentric rings on upper surface	(see P. igniarius)	knots, branch stubs and wounds
Fomes fomentarius	a) white or grey b) brown	hoof-shaped, perennial, concentric rings on upper surface	slight brown discoloration yellow- white spongy rot, brown-black zone lines	wounds