Malvastrum mosaic

The causative agent of the disease is the Begomovirus malvastrummusivi, a member of the Geminiviridae family. This virus contains a single-stranded DNA genome and is categorized as a systemic pathogen. The disease manifests as a mosaic pattern, severely impacting the host's photosynthetic capacity and overall developmental physiology.

The primary hosts of this virus are plants belonging to the Malvaceae family. Specifically, it affects species of Malvastrum, Hibiscus, and cotton (Gossypium). The virus is highly persistent in wild malvaceous weeds, which act as primary inoculum sources in agricultural and garden landscapes.

Symptoms of the infection include distinct chlorotic mosaic patterns on foliage, accompanied by leaf curling, crinkling, and a reduction in overall leaf size. Infected plants often exhibit severe stunting, shortened internodes, and reduced flower production. In advanced stages, the foliage may show significant tissue necrosis or complete deformation.

Transmission occurs primarily through the silverleaf whitefly (Bemisia tabaci), which acts as the viral vector. The whitefly acquires the virus during feeding and remains capable of transmitting it to healthy plants for an extended period. Environmental conditions such as warm temperatures and high humidity significantly favor whitefly activity, leading to rapid spread within a field.

Control strategies for managing the spread of this virus include:

• Rigorous weed control to eliminate alternate hosts of both the virus and its vector.
• Monitoring and management of whitefly populations using systemic insecticides.
• Removal and destruction of infected symptomatic plants to prevent secondary transmission.
• Utilization of physical barriers, such as insect-proof nets in greenhouses.
• Adherence to strict sanitation protocols to ensure the cleanliness of nursery stock.