Analyses of Virus Disease Management Programs

Complex management programs to reduce losses from plant virus diseases are necessary for those diseases, such as lettuce infectious yellows, that have no obvious single approach to mitigating losses. It may be possible by a carefully designed program to reduce or delay infection but such programs must be carefully designed, and managed. Such programs might require efforts to be directed toward several different aspects of the epidemiology of the disease such as weed control, timing of the crop, vector control, spatial arrangement of crops and crop plant spacing. These actions to be effective may require action at times of the year when the crop in question is not present and their effectiveness shows up only when at least several actions are taken in an integrated, coordinated way. Historically only a few such programs have worked because they are difficult to conduct and demonstrate effectiveness. By using geographical information systems (GIS), geostatistics, and associated software, we can develop a method of analyzing such management programs to demonstrate not only their effectiveness but also make improvements.