ABSTRACT
Models have been used to describe the behavior of phenomena for centuries. Beginning in the 1950s, models in the form of computer programs began to proliferate in a number of sciences. As interactive programming on the Internet became popular in the early twenty-Žrst century, there was a growing interest among professionals in government, academia, and business to access models online in order to monitor the day-to-day behavior of some phenomenon, such as pest movement in agriculture. This chapter introduces the reader to the principles of an aerobiology process model, including the components of preconditioning in source area, take-off/ascent, horizontal transport, descent/landing, and impact at destination. These model principles are put into practice for one pest-the fungus Puccinia graminis f.sp. tritici (Pgt), which is known by its common name “wheat stem rust.” Instructions are provided in the chapter on how a reader as a user can go to a Web site and conŽgure one of the components of the online aerobiology process model. After conŽguring the online model, the reader can execute the model and create a simulation for a geographic area and year. By comparing simulations between locations and years, a user can appreciate the different geographic and seasonal behaviors of the wheat stem rust disease. With the chapter as a guide and the online experience, a reader will also gain an appreciation of the role model simulations play in describing the spread of a disease in the conterminous United States.
