The effect of rust on yield of faba bean cultivars and slow-rusting populations.
Field studies were conducted in 1983 and 1984 to assess the effect of rust (Uromyces viciae-fabae) on pods per plant, seed per plant, seed per pod, total dry matter and harvest index in two faba bean (Vicia faba) cultivars and one susceptible line. The effect of rust was also assessed on the yield of 14 slow-rusting populations. Rust epidemics were created by artificial inoculation and healthy control plots were protected from rust by fungicide applications. Rust severity remained low in the cultivars Diana and Herz Freya and seed yield of each cultivar was reduced by 3.8-6.6% and 6.3-9.7% in 1983 and 1984, respectively. Rust became severe in the susceptible line 2N40 and significantly reduced some yield components and thereby yields by 67.9% and 49.5% in 1983 and 1984, respectively. Rust caused yield losses of only 1-2% in the slow-rusting population 2N43, of 1-11% in slow-rusting populations from Erfordia and Diana, and of 6-43% in other slow-rusting populations, indicating that some slow-rusting populations are more tolerant to rust than others.