Uromyces viciae-fabae

Uromyces viciae-fabae var. viciae-fabae is a plant pathogen commonly known as Faba-bean rust. The rust is distinguished by the typical rust-like marks on the stem and leaves, causing defoliation and loss of photosynthetic surface along with reduction in yield. The disease is fungal and is autoecious meaning it has one plant host. The rust of faba beans is macrocyclic, or contains 5 spores during its life cycle. Faba bean rust has a complex lifecycle containing three different stages. Each stage of the cycle has different symptoms. Faba bean rust grows best in July and August as the weather in these months is most fit. The required environment for infection after spores land on a plant consists of rainfall or dew. Also, weather that is humid and warm promotes the spread. Spores can be spread by wind to other plants. An important factor in development of rust epidemics is the infection of volunteer faba bean plants. The disease cycle is as follows: the overwintering diploid teliospores germinate in the spring with metabasidium forming four haploid basidiospores of two mating types, types (+) and (-) are formed. Next haploid pycniospores are exchanged between pycnidia of different mating types on the upper leaf surface.