Broad bean wilt virus

Broad bean wilt virus (BBWV) is a significant plant pathogen classified within the genus Fabavirus of the Secoviridae family. The virus consists of icosahedral particles containing a bipartite positive-sense single-stranded RNA genome. It is recognized as a major cause of disease in various legume and vegetable crops, leading to significant economic losses in temperate and subtropical climates.

The host range of BBWV is remarkably diverse. While it primarily infects members of the Fabaceae family, such as broad beans (Vicia faba), it also affects a wide variety of other crops, including tomatoes, spinach, lettuce, parsley, and various ornamental species like petunias. Symptoms are typically characterized by systemic mosaic patterns, leaf deformation, stunting of the plant, and significant wilting, which may result in plant collapse.

The biology and lifecycle of BBWV are dependent on insect vectors, specifically aphids. The virus is transmitted in a non-persistent, non-circulative manner. Aphids such as Myzus persicae and Aphis fabae acquire the virus by probing infected plant tissues and can immediately transmit it to healthy plants during subsequent feeding. The virus does not replicate within the vector, and the aphid loses its infectivity rapidly as it continues to feed.

Disease progression is heavily influenced by environmental conditions that favor aphid migration and reproduction. BBWV overwinters in perennial weed reservoirs or on infected volunteer crops. When weather conditions permit, mass movement of aphids leads to rapid secondary spread throughout the fields. High levels of viral incidence are often correlated with peak aphid population densities during the active growing season of the host plants.

The economic impact of this pathogen is reflected in reduced crop quality and quantity, often rendering the harvest unmarketable. Management and control strategies focus on integrated pest management (IPM) practices, such as:

• Utilizing virus-free planting stocks or certified seeds.
• Implementing weed management to eliminate alternative viral hosts.
• Applying insecticides to suppress aphid vector populations during critical growth stages.
• Utilizing physical barriers like row covers to protect sensitive seedlings.