Hazelnut latent virus

The virus particles are spherical and contain a positive-sense single-stranded RNA genome, which is typical for the Ilarvirus group.

Transmission occurs primarily through vegetative propagation using infected scions or rootstocks. This is the main way the virus spreads across different orchard locations.

Additionally, pollen and seed transmission have been reported, making the containment of this pathogen difficult in commercial hazelnut production.

Because the infection is often latent, the virus can spread silently through nurseries and orchards for years before causing visible issues.

The most common symptom is mild, systemic chlorosis or yellowing of the leaves, which often appears in a mottled or speckled pattern.

Symptoms are frequently transient and may fluctuate depending on seasonal environmental conditions, making detection difficult during summer.

In some cases, infected hazelnut trees may show reduced leaf size and stunted growth of young shoots compared to healthy trees.

Unlike other serious hazelnut diseases, HLV does not typically cause bark necrosis or severe wilting, which leads many growers to overlook the infection.

Symptoms can often be confused with nutritional deficiencies or drought stress, necessitating laboratory confirmation for an accurate diagnosis.

The economic impact of HLV is mainly associated with reduced yield and lower quality of nuts, including kernel shrinkage.

The virus compromises the overall vigor of the trees, making them more susceptible to other biotic and abiotic stress factors.

Over several seasons, the vigor of the infected trees declines, leading to poor nut set and irregular production cycles.

The presence of the virus in an orchard decreases the tree's lifespan, eventually leading to a drop in the productivity of the entire stand.

The systemic nature of the virus ensures that once a tree is infected, it remains a reservoir for the pathogen for the rest of its life.

The most effective strategy is to plant only certified virus-free nursery stock that has been tested by accredited laboratories.

Rigorous sanitation measures should be implemented, including the disinfection of pruning tools with appropriate chemical agents between trees.

If an infection is identified, the affected trees should be rogueed and removed from the orchard to prevent further spread.

Monitoring the orchard for vectors that could potentially spread the virus is a critical part of a comprehensive disease management program.

• Implement strict quarantine protocols for imported plant material.
• Conduct regular ELISA or PCR testing for early detection of latent infections.