Peronospora viciae

Peronospora viciae is a species of oomycete that causes downy mildew on plants in the Fabaceae family, particularly those in the Vicia genus. This pathogen is a significant problem in agricultural systems, where it can cause severe yield losses in crops such as field peas and faba beans.

Life Cycle

The life cycle of Peronospora viciae involves both asexual and sexual reproduction. The asexual phase begins when sporangia are produced on the surface of infected plants. These sporangia can be spread by wind or rain to new host plants, where they germinate and infect the plant. The sexual phase involves the production of oospores, which can survive in the soil for several years and initiate new infections when conditions are favourable.

Symptoms and Diagnosis

Symptoms of Peronospora viciae infection include yellowing and wilting of leaves, and the appearance of a downy, purplish-grey growth on the underside of leaves. In severe infections, the pathogen can also infect stems and pods, causing them to become discoloured and distorted. Diagnosis is typically based on these symptoms, and can be confirmed by microscopic examination of the pathogen.

Management

Management of Peronospora viciae involves a combination of cultural practices and chemical control. Cultural practices include crop rotation and the use of resistant varieties. Chemical control typically involves the application of fungicides, although the effectiveness of these can be limited by the development of resistance in the pathogen.

Impact

Peronospora viciae can cause significant yield losses in susceptible crops. In addition to reducing the quantity of the harvest, the pathogen can also affect the quality of the crop, as infected seeds are often discoloured and shrivelled.

See Also

• Downy mildew
• Oomycete
• Vicia