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