Bean IPM

Legume ipmPIPE Diagnostic Series

Common Rust

Uromyces appendiculatus


Figure 1 Reddish brown, circular pustules or uredinia up to 6 mm in diameter (¼ inch) form on leaves or stems, rarely pods. uredinia may be surrounded by a yellow halo, and commonly occur on both surfaces of leaves.

Figure 2 Spores feel like fine powder, and leavedusty streaks when uredinia are rubbed.

Figure 3 Dark brown to black telia up to 6 mm in diameter (¼ inch) may form on leaves, stems or pods later in the season. This spore stage will overwinter and does not re-infect current season beans.

Factors favoring
  • Infested debris and volunteers from previous season
  • Rainstorms, dew, fog and irrigation
  • Regional weather systems and wind patterns
  • Moderate temperatures with daily highs less than 30°C [86°F], especially during V4 to R4 growth stages
  • Delayed maturity may expose legumes to lateseason disease pressure
Red bumps on leaf
Figure 1
Finger showing spores after rubbing leaf
Figure 2
Raised dark bumps on stem
Figure 3

H.F. Schwartz, Colorado State University and S.G. Markell, North Dakota State University

Photo credits

Courtesy of H. F. Schwartz & S. G. Markell [08/09]