Scouting for soybean rust can be difficult. Symptoms on the top of the leaf can be confused with bacterial pustule as well as Septoria brown spot and even spider mite feeding on the soybean leaf. The pustules, formed by the fungus that produce sporulation and result in additional infection, are formed on the underside of the leaf. The pustules appear like small blisters, are light tan in color, and typically can be observed quite well with a 20× hand lens. To confirm soybean rust, use the hand lens to observe the pustules on the bottom of the leaf.