Tomato leaf curl Solanum-Arusha virus

The virus consists of a single-stranded circular DNA genome, which is encapsulated in twinned, incomplete icosahedral particles characteristic of the geminivirus family.

It is primarily transmitted in a persistent, circulative, and non-propagative manner by the whitefly species Bemisia tabaci.

The virus enters the host plant through the phloem during the feeding process of the whitefly vector and eventually colonizes the entire vascular system.

Due to the global movement of plant materials and the wide distribution of its vectors, this virus poses a constant threat to sustainable tomato production.

Infected tomato plants display characteristic symptoms of severe leaf curling, where the edges of the leaflets curl upward and inward.

A noticeable yellowing or chlorosis of the leaves is common, often appearing as distinct mosaic patterns or a general fading of the green color.

Stunted growth is a hallmark of the infection, with plants appearing bushy and compact due to the shortening of internodes along the main stem.

The development of flowers is severely affected, frequently resulting in flower drop and a subsequent lack of fruit formation.

If fruits do manage to develop on diseased plants, they are typically undersized, distorted, and lack the nutritional quality required for market standards.

The prevalence of the virus is highly dependent on the population dynamics of its whitefly vector, which thrives in warm and dry climate conditions.

High temperatures accelerate the life cycle of the whitefly, leading to exponential population growth and increased probability of virus transmission.

The presence of alternative weed hosts, such as various species within the Solanaceae family, allows the virus to survive throughout the year.

Greenhouse environments often provide an optimal microclimate for both the vector and the virus to propagate, especially if ventilation is not properly screened.

Poor agricultural practices, including dense planting and the failure to remove infected plant debris, contribute to the rapid spread of the pathogen.

This virus is considered highly destructive, as infection at the seedling stage often results in a complete loss of crop yield for the affected field.

Beyond direct yield loss, the virus weakens the host plant's immunity, making it susceptible to secondary infections by various fungal and bacterial pathogens.

The aesthetic and physical quality of the fruit is severely degraded, rendering the harvest unmarketable for fresh consumption or industrial processing.

Increased input costs for intensive pest management programs to control whitefly populations add significantly to the overall economic burden on growers.

The persistent nature of the disease often necessitates drastic measures such as the eradication of entire crop cycles to prevent further local spread.

Management strategies focus primarily on excluding the whitefly vector and developing host plant resistance to the viral pathogen.

Producers are advised to implement strict sanitation practices, including the removal of infected plants and surrounding weed reservoirs immediately upon detection.

In protected cultivation, the use of fine-mesh insect-proof netting is an effective physical barrier that prevents whitefly entry into the greenhouses.

Integrated Pest Management (IPM) is crucial, combining biological control agents, targeted insecticide applications, and cultural practices like crop rotation.

• Utilizing disease-resistant or tolerant tomato cultivars.
• Establishing long-term monitoring for whitefly populations.
• Applying systemic insecticides to minimize vector numbers.
• Ensuring geographical isolation between different crop successions.