These categories estimate the risk of soybean rust infecting the Iowa soybean crop. These categories do NOT represent potential yield loss due to soybean rust and should not be used to decide when to apply fungicides to manage soybean rust.

None: Soybean crop in Iowa is before growth stage R1 (beginning flowering) or after growth stage R6 (full seed).

Management: none

Low: Soybean crop in Iowa is between growth stages R1 (beginning flowering) and R6 (full seed). Soybean rust development is restricted to southern states and/or weather forecast is average or below average for precipitation.

Management: none

Medium: Soybean crop in Iowa is between growth stages R1 (beginning flowering) and R6 (full seed). Soybean rust has been confirmed in a neighboring state and/or predictive models suggest that spores may have landed in Iowa.

Management: may be warranted in near future based on weather forecast

High: Soybean crop in Iowa is between growth stages R1 (beginning flowering) and R6 (full seed). Soybean rust has been confirmed in Iowa and/or predictive models suggest infection of soybeans in Iowa is likely.

Management: may be warranted if yield losses are expected

For more information, contact the Iowa Soybean Rust Team