Garlic allexivirus

The main symptoms of the infection include leaf mosaic patterns, characterized by alternating shades of light and dark green or yellow stripes.

Infected garlic plants frequently show signs of stunted growth, reaching a significantly smaller height compared to healthy specimens in the same field.

Leaf deformation is a common sign, where leaves may appear twisted, curled, or exhibit wavy margins, hindering normal growth processes.

The bulbs of infected plants are typically smaller, have poorer quality outer scales, and show reduced storage stability after the harvest.

• Chlorotic striping and mosaic patterns on leaves.
• Stunted plant development.
• Deformed and curled leaf blades.
• Reduced bulb diameter and weight.

The causative agent of the disease is Allexivirus betallii, a member of the genus Allexivirus within the family Alphaflexiviridae. This virus is characterized by flexuous filamentous particles containing single-stranded RNA.

It is a viral disease that typically manifests in a latent or systemic form, often remaining undetected during the early stages of plant development.

The primary reservoir for the virus is infected garlic cloves used for planting. The virus survives strictly within living plant tissues and is highly dependent on its host.

The pathogenesis involves viral replication within the plant cells, leading to a disruption of normal cell functions and a decrease in overall plant vigor.

Allexiviruses are known to often exist in mixed infections with other garlic viruses, which significantly complicates the clinical diagnosis of the condition.

The most critical factor in the spread of the virus is the planting of infested cloves, which carries the infection from one season to the next.

Vectors play a vital role in transmission; the garlic bulb mite (Aceria tulipae) is known to be a significant carrier of the virus in field conditions.

Mechanical transmission occurs through contaminated tools used for pruning garlic scapes or harvesting, which facilitates the spread of the virus between plants.

Environmental conditions that favor the population growth of mites, such as high temperatures and relative humidity, indirectly exacerbate the spread of the virus.

Close spacing of plants and monoculture practices facilitate easy movement of vectors and increase the risk of rapid systemic infection across the field.

The harm caused by garlic allexivirus is primarily manifested in substantial yield reduction, which can severely impact the economic viability of the garlic crop.

The virus impairs photosynthesis, which leads to lower accumulation of dry matter and nutrients in the bulb, resulting in inferior produce quality.

Viral infection weakens the plant's immune system, making it significantly more susceptible to secondary fungal and bacterial rot infections during storage.

Continuous propagation using infected material leads to the gradual degeneration of high-quality garlic varieties, resulting in a loss of vigor and yield potential.

Because there are no chemical treatments available to cure viral infections once a plant is infected, the economic losses represent a permanent reduction in profitability for the season.

The primary prevention strategy is the exclusive use of high-quality, virus-free planting material, ideally sourced from specialized tissue culture programs.

Implementing strict phytosanitary measures, including the immediate removal and destruction of symptomatic plants, helps to reduce the inoculum pressure in the field.

Control of vectors, specifically the garlic bulb mite, is essential to minimize the secondary spread of the virus during the active growing season.

Regular sanitation of agricultural tools and equipment using approved disinfectants is necessary to prevent mechanical transmission during field maintenance.

Adopting proper crop rotation practices helps manage the population of soil-borne vectors and breaks the life cycle of the pathogen between growing seasons.