Order Info Disease Symptoms Source and Spread Factors Favoring Epidemics Rust Management Rust is an important disease that affects dry beans in eastern Colorado, western Nebraska and adjacent regions. The disease is caused by the fungus Uromyces appendiculatus which has caused periodic epidemics in this region since the 1950s. Recent yield losses from the disease have exceeded 50 percent in some areas. Pustules may be surrounded by a yellow border. Rust can be distinguished from other leaf spots because the rust-colored spores will rub off, while with blights and bronzing, nothing rubs off.
Severe infection causes leaves to curl upward, dry up, turn brown and drop prematurely.
Pod set, pod fill and seed size can be reduced if infection is severe. Green pods, and occasionally stems and branches, also may become infected and develop typical rust pustules. However, bean rust is not seedborne. Bean debris containing this overwintering phase provides for early season infection the following year. This has contributed to rust epidemics in eastern Colorado and western Nebraska and is a factor in northern states such as North Dakota and Minnesota.