Rust Mapper is an interactive Google Earth based application created and hosted by the GIS Unit at CIMMYT. It displays current rust survey sites, near real-time wind trajectories from sites reporting stem rust (all races, not only Ug99), major wheat growing areas and country wheat statistics. Near-real time wind trajectories (24, 48 & 72 hours, starting at 500m above ground) from known stem rust sites are generated using the NOAA HYSPLIT model.The browser-based version “Rust Mapper Web” is replicated here – this requires download of the free Google Earth plug-in developed by Google. If Rust Mapper Web does not load, simply click on the “Get the Google Earth Plug in now” button. A full Google Earth version of Rust Mapper can be obtained from http://apps.cimmyt.org/gis/RustMapper/index.htm