Sweet potato leaf curl Georgia virus

Biologically, the virus is transmitted in a semi-persistent manner through a specific vector, the whitefly Bemisia tabaci. Viral particles accumulate in the phloem tissues of the host plant, which hinders the circulation of nutrients and water.

The leaf curl virus is characterized by a high capacity for recombination with other members of the Begomovirus genus. This poses a threat of the emergence of new, more virulent strains in regions of intensive crop cultivation.

The viral genome is adapted to tropical and subtropical conditions, where its primary vector, the whitefly, remains active year-round. The virus is not seed-transmitted but spreads easily through infected planting material.

Diagnosis of the disease is complicated by the fact that the virus is often found in mixed infections along with other pathogens. For accurate identification, molecular genetic methods such as RT-PCR are used.

The main sign of the disease is characteristic upward curling of the leaf blades, accompanied by deformation. Leaves often become wrinkled and lose their natural glossy sheen.

Affected plants show pronounced yellowing (chlorosis) of leaf margins or interveinal spaces. In some cases, a mosaic pattern appears, which becomes more noticeable under strong sunlight.

Plants infected with the virus show stunted growth and shortened internodes. The formation of the plant canopy becomes asymmetrical, and the total vegetative mass is significantly reduced compared to healthy specimens.

Sweet potato tubers become smaller when affected by the virus and lose their marketability. There is often a decrease in their density, as well as a change in shape, making the harvest unsuitable for long-term storage and sale.

During visual inspection, colonies of whiteflies—the virus vector—can often be found on the underside of the leaves. Symptoms may vary depending on the sweet potato variety and the age of the plant at the time of infection.

The development of the virus depends directly on the population density of the whitefly. The most intense infection occurs in hot and dry weather, which facilitates the rapid reproduction of vector insects.

The spread of the virus is promoted by the lack of crop rotation and the presence of weed reservoirs belonging to the Convolvulaceae family. Weeds allow the virus to persist in the field even after the main harvest is completed.

The optimal temperature for vector reproduction and virus development is between 25 and 30 degrees Celsius. In temperate climates, viral activity decreases, but vectors may survive in greenhouses.

The use of infected vegetative material (cuttings) is a major factor in the spread of the virus to new areas. The virus can exist in a latent form, where external signs of infection are temporarily absent.

Migratory flows of insects over long distances due to wind or agricultural machinery facilitate the spread of the infection to new fields. High planting density only accelerates the pathogen's spread within a single plot.

The Sweet potato leaf curl Georgia virus causes significant economic losses for farmers. The primary consequence is a reduction in overall yield, which can drop by 30–50% under severe infection.

The loss of tuber quality makes them impossible to sell through retail networks. Small, deformed tubers have low culinary characteristics, which devalues the results of agricultural labor.

Infection with the virus weakens the plant's physiological immunity, making it vulnerable to secondary fungal and bacterial infections. This leads to premature wilting and death of the entire crop in the field.

The costs of implementing control measures against the virus vector significantly increase production costs. Regular insecticide applications become mandatory, which increases environmental pressure.

Infected material becomes a source for future seasons. In regions where sweet potatoes are grown as a perennial, the virus gradually leads to the complete degeneration of existing varieties.

The main prevention method is the use of virus-free planting material obtained through tissue culture (meristem culture) in laboratory conditions. It is important to purchase cuttings only from certified nurseries.

Combating the whitefly is a critical link in protection. Regular monitoring of insect populations and the use of approved systemic and contact insecticides are necessary.

Maintaining spatial isolation between new sweet potato plantings and old, infected plots is recommended. The destruction of weeds that can serve as a refuge for the vector and a virus reservoir is mandatory.

Implementing crop rotation helps break the cycle of virus development in the soil and on plant residues. In regions with a high threat of spread, the use of mesh coverings for young plantings is recommended.

Breeding and utilizing sweet potato varieties that possess genetic resistance to begomoviruses is the most effective and long-term way to solve the crop protection problem.