DISEASES SOYBEAN – SOYBEAN RUST

Soybean rust is a disease that has never been found in Wisconsin, but has significant impact on soybean production in South America. Soybean rust first occurred in the continental United States in 2004, when spores of rust fungus (Phakopsora pachyrhizi) are thought to have been brought into country from South America by hurricane Ivan. Soybean rust has become established in the southern US where it overwinters primarily on kudzu (another plant that the pathogen can infect).

Initial symptoms of soybean rust tend to occur in the mid canopy where air-borne spores can settle and wetter environmental conditions are more favorable for the rust pathogen to germinate and infect. From a distance, infected leaves will appear yellow and eventually necrotic (i.e., dead).