Premna begomovirus

The main signs of infection include a distinct chlorotic mosaic on leaf blades, often alternating with patches of healthy tissue.

Characteristic leaf curling and deformation are observed, which are associated with the disruption of hormonal balance in plant tissues caused by the virus.

The growth of affected plants is significantly stunted, internodes are shortened, resulting in a dwarfed appearance.

Flowering becomes extremely weak or ceases entirely, and any fruits that do set develop as small and underdeveloped.

In some cases, leaf margins turn yellow or become concave, significantly reducing the plant's ornamental appeal.

The causative agent of the disease is a virus from the genus Begomovirus (family Geminiviridae), which specifically affects plants of the genus Premna.

These viruses are characterized by a single-stranded DNA genome and have distinct geminiform particles—paired icosahedral capsids.

The virus is transmitted exclusively in a semi-persistent manner by specific insect vectors from the whitefly family (Aleyrodidae).

The infection process begins when virus particles are introduced into the host plant's phloem during insect feeding.

The viral genetic material rapidly replicates in the nuclei of plant cells, causing a systemic infection that spreads to all vegetative organs.

The spread of the virus is directly dependent on the population of whiteflies, which act as the primary vectors of the infection in the field.

Favorable conditions for the development of the disease are created during high air temperatures and moderate humidity, which promote active insect reproduction.

Failure to control weeds, which can act as viral reservoirs during off-seasons, significantly increases the risk of crop contamination.

Crowded plantings and poor ventilation in greenhouses or nurseries create a microclimate ideal for vector movement from infected plants to healthy ones.

The presence of other Verbenaceae family species in the vicinity increases the probability of virus persistence within the agroecosystem.

The damage caused by Premna begomovirus involves a critical loss of ornamental value and biological productivity in affected crops.

Systemic infection leads to the death of young shoots and a decline in overall plant vitality, often resulting in mortality over several seasons.

Economic losses are linked to the loss of commercial quality of ornamental plants and their unsuitability for landscaping purposes.

In nurseries, the presence of the virus can lead to the total culling of plant batches due to the high risk of epiphytotics.

Infected plants become extremely vulnerable to secondary infections by fungal or bacterial pathogens due to their compromised immune system.

The main control measure is the eradication of insect vectors through regular applications of systemic insecticides during peak flight periods.

It is crucial to timely identify, remove, and destroy any plants showing signs of viral infection to break the chain of transmission.

It is recommended to use only healthy, virus-tested planting material, especially when introducing new plants into a collection.

Preventive strategies include maintaining field sanitation and controlling weeds that can serve as hidden reservoirs for the virus.

• Use of insect-proof netting in greenhouses
• Disinfection of pruning tools after each contact with a plant
• Strict quarantine measures for new nursery additions