Compartmentalization of decay in trees
Compartmentalization of decay in trees (CODIT) is a concept created by plant pathologist Alex Shigo after studying wood-decay fungus patterns. Theoretical background. In keeping with the theory of spontaneous generation, in which living things can develop from non-living things, scientists traditionally believed that tree decay led to fungal growth. With the advent of germ theory, however, German forester Robert Hartig in the early 20th century theorized the opposite was the case, and developed a new model for tree decay: when trees are wounded, fungi infect the wounds, and the result is decayed wood . Shigo expanded this theory to claim that when trees are wounded, they respond to the infected wood with both chemical and physical changes to limit the decay, which he called "compartmentalization". Process. According to CODIT, when a tree is wounded cells undergo changes to form "walls" around the wound, slowing or preventing the spread of disease and decay to the rest of the tree. Practical impact. By increasing understanding of how trees respond to decay, CODIT has had many applications. For example, arborists are frequently called upon to analyze the danger posed to people or property by a damaged or  decaying tree. By knowing how decay is likely to spread, such hazard tree analyses may be more accurate, thereby preventing unnecessary tree removal, property damage, or injury. Work done by Gilman et al. at the University of Florida shows that a wound's proximity to leaf mass greatly influences compartmentalization as well as wound closure.