Seed infections appear as dark lesions and result from pod infections. B. Ascospores produced by perithecia on stubble are blown by wind and rain to infect seedlings. C. Pycnidia form in lesions on seedlings. As the crop grows, conidiospores from pycnida spread the disease in the canopy by rainsplash. E. Disease infested stubble remains after harvest.
Infected seed is harvested with healthy seed.
The tan centre in this lesion is an old chocolate spot lesion. Cercospora spots have irregular edges and may develop a ring pattern inside the spot. It is necessary to correctly identify leaf diseases before applying control strategies to produce a successful faba bean crop. The fungi Alternaria and Cercospora cause minor diseases that are not yield limiting. However, they can both be confused with ascochyta blight.