ABSTRACT
Injury has been characterized as the effect of pest activities on host physiology that is usually deleterious.1 The actual characterization and quantification of specific forms of injury, however, are very complex and dynamic, affected by both the pest and the host. Injury can be a discrete event such as a larva cutting a young seedling where the resultant damage is immediate, acute, and easily measured. In contrast, injury may also be a slow and continuous process, such as soil insects affecting root tissue, which reduces transpiration over a season-long host growth cycle, but resultant damage is highly dependent upon environmental circumstances. This latter case, where injury is a continuous process to reduce host vigor, frequently is difficult to assess and represents one of many components to the “black box” relationship with regard to host yield (see Chapter 1). To establish a cause-and-effect relationship, some rational segregation and quantification of component injury must be achieved.
