Mulberry nepovirus

Mulberry nepovirus (Nepovirus mori) is a significant viral disease affecting trees of the genus Morus. Belonging to the Nepovirus genus, this pathogen typically infects the host's vascular tissues, disrupting vital physiological processes, including nutrient transport and gas exchange, which eventually leads to the systemic decline of the plant.

The primary host for this virus is the mulberry tree, which is economically significant in silk production and orchard management. The virus can affect both young nursery stock and mature trees. The impact of the pathogen is severe, often resulting in long-term damage that compromises the structural and physiological integrity of the infected specimen.

Symptoms of the infection include leaf mosaic patterns, yellowing (chlorosis) along the veins, stunted shoot growth, and abnormal leaf deformation. Severely infected trees show reduced canopy density, delayed bud break, and a noticeable decrease in fruit yield. In some instances, the bark may show signs of necrosis, indicating deep physiological stress within the tree.

Transmission occurs primarily through soil-borne nematodes, which act as vectors by feeding on the root systems of infected trees. Furthermore, the virus is easily spread by human intervention; contaminated pruning shears, grafting knives, and other horticultural tools serve as major vectors when they are not sanitized between uses. Infected scion wood used for grafting is also a major source of spreading the virus to new areas.

Management of this disease relies heavily on prevention and strict hygiene protocols. It is essential to source healthy, virus-indexed nursery stock and to implement rigorous nematode control strategies in the soil.

• Regular sterilization of pruning equipment with approved disinfectants.
• Immediate removal and destruction of symptomatic trees.
• Monitoring nurseries for any signs of viral infection.