Mulberry mosaic

Mulberry mosaic is a viral disease affecting trees of the genus Morus. The causative agent is the Mulberry mosaic virus, a systemic plant pathogen that disrupts the metabolic processes within the host plant's tissues. As a viral infection, it cannot be cured with chemical fungicides, making early detection and preventive measures critical for plant health management.

The primary hosts of this disease are various species of mulberry (white and black mulberry). While mature trees may show varying degrees of tolerance, the impact is most severe in young nursery stock and trees maintained for intensive leaf production. The virus colonizes the vascular system, allowing it to move throughout the entire tree structure.

Symptoms of the disease are characterized by irregular patches of light green, yellow, or white on the leaf surface, creating a distinct mosaic pattern. Infected leaves may exhibit crinkling, malformation, and a reduction in size. In severe cases, the infected trees demonstrate stunted growth, reduced vigor, and a general decline in canopy health during the peak growing season.

The virus spreads primarily through vegetative propagation using infected scions or rootstocks. Additionally, insect vectors, such as aphids and certain mite species, play a significant role in transmitting the virus from diseased to healthy trees. Environmental factors that promote the population growth of these vectors indirectly increase the rate of viral transmission within the orchard.

Management of Mulberry mosaic relies heavily on exclusionary practices and cultural control. Once a tree is infected, the virus remains present for its entire lifespan. Therefore, producers must ensure the use of certified virus-free planting material. Control of sap-sucking insect populations and strict sanitation of pruning equipment are essential steps in limiting the spread of the pathogen within the orchard or nursery environment.