Decay – The decomposition of wood by fungi
Advanced Decay – The older stage of decay in which the destruction is readily recognized because the wood has become punky, soft and spongy, stringy, pitted, and crumbly.
Brown Rot – In wood, any decay in which the attack concentrates on the cellulose and associated carbohydrates rather than on the lignin, producing a light to dark brown residue.
Dry Rot – A term loosely applied to any dry, crumbly rot but especially to that which, when in an advanced stage, permits the wood to be crushed easily to a dry powder.
Incipient Decay – The early stage of decay that has not proceeded far enough to soften or otherwise perceptibly impair the hardness of the wood.
Heart Rot – Any rot characteristically confined to the heartwood. It generally originates in the living tree.
Pocket Rot – Advanced decay that appears in the form of a hole or pocket, usually surrounded by apparently sound wood.
Soft Rot – A special type of decay developing under very wet conditions in the outer wood layers, caused by cellulose-destroying micro-fungi that attack the secondary cell walls and not the intercellular layer.
White Rot – Any decay or rot attacking both the cellulose and the lignin, producing a generally whitish reside that may be spongy or stringy rot, or occur as pocket rot.
Decaying Knot – A knot is disintegration of wood due to the action of wood-destroying fungi.