Rhynchosia golden mosaic virus

Pathogen and disease type. The Rhynchosia golden mosaic virus, classified as Begomovirus rhynchosiaurei, is a viral agent belonging to the Geminiviridae family. As a typical member of the Begomovirus genus, it possesses a circular single-stranded DNA genome. The virus causes a systemic infection, primarily impacting the plant's vascular tissue, which leads to substantial disruption of the host's physiological processes.

Host range. The virus was originally identified in various species of the Rhynchosia genus, which act as primary wild reservoirs. However, its host range includes various leguminous crops, posing a significant risk to agricultural production in regions where these crops are cultivated. The presence of overlapping host ranges between wild weeds and agricultural crops facilitates the maintenance of the virus in the environment.

Symptoms and signs. Infected plants exhibit classic symptoms including bright yellow or golden mosaic patterns, leaf mottling, and yellowing. Further progression of the disease often results in leaf curling, crinkling, and significant stunting of the plant. These symptoms directly correlate with reduced photosynthetic efficiency, which ultimately compromises the development of flowers and fruit.

Development and transmission. The virus is transmitted exclusively by the whitefly Bemisia tabaci in a persistent circulative manner. Once the insect acquires the virus by feeding on an infected plant, it remains a vector for the duration of its lifespan. Environmental conditions that support high whitefly populations, such as warm temperatures and low humidity, are the primary drivers for the rapid spread of the disease.

Harmfulness and protection measures. The impact of Begomovirus rhynchosiaurei on crop yield can be devastating, leading to poor plant vigor and reduced grain quality. Since there is no curative treatment for viral plant infections, management strategies must focus on prevention and vector control:

• Eradication of weed hosts that serve as virus reservoirs.
• Implementation of integrated pest management (IPM) to control whitefly populations.
• Utilization of certified virus-free seeds and planting materials.
• Deployment of physical barriers or reflective mulches to deter insect vectors.