The national movement of rust should be closely followed. If rust development in the southern U.S. is slow, local scouting efforts can be delayed. If needed, local scouting should be before the R6 growth stage (late August).

Finding early infection (low incidence and severity) while in the field is very difficult. Shaded areas in a field or areas with dense canopy should provide the best environment for rust development, so these areas should be scouted. If rust is suspected, a minimum of 100 leaves per field should be collected from the lower-to-mid canopy. Detecting low levels of soybean rust typically requires incubating samples for 24 to 48 hours and observing them under laboratory conditions by a trained diagnostician.

In the event that soybean rust has become severe enough to be identified in the field, it may be identified by examining the underside of leaves for pustules using a hand lens.