Soybean rust fungus symptoms begin on leaves in the lower plant canopy. Tan or reddish-brown lesions (spots) develop first on the underside of leaves. Small pustules (blisters) develop in the lesions, which break open and release masses of tan spores. The lesions and pustules, which can be seen with a 20X hand lens, may also appear on pods and stems. Early symptoms of soybean rust (before pustules develop) are difficult to distinguish from other common leaf diseases on soybean.