Figure 1.

Common bean rust symptoms, rust pustules, and spores. (a) Ten-day-old seedlings at the primary leaf stage were inoculated with rust race 53. The susceptible genotype Olathe and susceptible mutant crg developed visible rust like symptoms after approximately 10 days of inoculation, whereas the resistant genotype Sierra was asymptomatic as expected. The genotypes Olathe and crg were used as an inoculation experimental control only and are shown here. (b–e) Scanning electron microscope pictures from a leaf of a rust susceptible genotype crg after symptoms were developed. Picture (b) is an unopened rust pustule. ((c) and (d)) Pustules which burst open at 120 and 500 times' magnification. (e) Rust spore under 3000 times' magnification. White arrows point to the pustules and fungal spores.