DISCOLORATION is a process. DECAY is a process. DISCOLORED and DECAYED wood represent the DISORDERED PRODUCT of an ORDERED material.
DISCOLORED WOOD results from an alteration of cell contents. There is only slight or no loss of strength. The tree AND the microorganisms are involved in the processes that result in discolored wood.
DECAYED wood is a result of a breakdown of cell walls. There is a great loss of strength.

Many microorganisms are involved in the processes that result in decayed wood. The wood cells have been killed and the decay-causing microorganisms compete among themselves for the dead matter. Many factors affect the rate of decay. The TREE has the greatest influence in the LIMITS of the decay column. Most of the events in the decay process are ORDERED. The classical concept of decay deals mostly with disordered events. It is impossible to regulate disorder.

The expanded concept of decay deals primarily with ORDERED events. The ordered system of trees and microorganisms is constantly impacted by many types of ordered and disordered events: Temperature extremes for short periods, moisture extremes for short periods, changing soil elements, storms, fires, logging operations, soil compaction, flooding, earthquakes, soil grade changes, pollution, chemicals, gas leakage, human-caused epidemics, or diseases and insects.
These factors alone or in combinations greatly affect the MICROORGANISMS and the TREE. The factors may alter the rate of the decay processes but not the patterns of successions and compartmentalization, which are ordered events.

For example,

1. SUCCESSIONS, an ORDERED process, often determine RATE. Upset the normal successions and the process will be stalled (not stopped). This can be done by purposely infecting wounds with microorganisms that normally occur late in the succession, such as with species of Trichoderma. The decay process will be stalled.
2. COMPARTMENTALIZATION represents order. Some trees have a stronger wound response than others; they can compartmentalize invaded tissues more effectively than other trees of the same species. The differences are shown in the next three illustrations.

Figure 84

When drill holes are inflicted in strong compartmentalizers, a pattern like this results-very short vertical columns and little to no lateral extension. (fig. 84)

When drill holes are inflicted into moderate compartmentalizers, a pattern like this results-long vertical columns and some lateral extension of discolored wood.(fig. 85)

When drill holes are inflicted in weak compartmentalizers, columns that look like this are seen-long vertical columns and complete lateral extension of discolored wood. (fig. 86)
The tree's response in the compartmentalization of discolored wood appears to be under strong genetic control.

Figure 85

Figure 86