Mulberry badnavirus

Mulberry badnavirus (Badnavirus mori) is a significant viral disease affecting mulberry trees (Morus spp.). The pathogen belongs to the Badnavirus genus, characterized by a double-stranded DNA genome. The virus spreads systemically within the host, disrupting vital physiological processes including nutrient transport and chlorophyll synthesis.

The host range is primarily limited to mulberry species used both in commercial sericulture and landscaping. The disease impacts trees at various stages of development, though younger trees are often more susceptible to severe damage. Infection leads to a progressive decline in the overall vigor and lifespan of the host plant.

Symptoms of the disease typically manifest as chlorotic spots, intricate mosaic patterns on leaves, and distinct leaf curling or distortion. Infected trees often show stunted growth, shortened internodes, and premature defoliation. In some instances, the severity of the symptoms can fluctuate based on the specific mulberry cultivar and local climatic conditions.

Transmission of the virus occurs primarily through vegetative propagation using infected plant materials, contaminated pruning tools, or insect vectors like mealybugs. Increased temperatures and humidity facilitate the activity of these vectors, which significantly enhances the spread of the pathogen throughout the orchard or nursery setting.

The economic impact of the virus is centered on the loss of leaf yield and quality, which is crucial for the silk industry. Currently, there is no chemical cure for viral infections in plants, making management dependent entirely on preventive strategies:

• planting only certified virus-free rootstock and grafts;
• systematic monitoring and rogueing of infected trees;
• disinfection of pruning tools between trees;
• integrated pest management (IPM) to control mealybug populations.