Ringspot

The primary diagnostic sign of the disease is the appearance of characteristic chlorotic or necrotic spots on leaves that form concentric circles or ring-shaped patterns.

Often, a yellowish halo forms around these rings, and the tissue in the center of the spot may dry out and fall away, resulting in shot-hole symptoms on the leaf blade.

Besides leaves, ringspot can manifest on fruits, where sunken spots develop, reducing the marketability of the produce and causing premature decay.

In the early stages of development, symptoms may be subtle, resembling mosaic patterns or mild chlorosis, which makes visual identification difficult without laboratory analysis.

In advanced cases, affected plants show significant growth stunting, leaf curling, fruit deformation, and general depression of the crop's physiological processes.

The group of diseases known as "ringspot" is caused primarily by phytopathogenic viruses, the most prevalent being Tobacco Ringspot Virus (TRSV) and Tomato Ringspot Virus (ToRSV).

These pathogens belong to a group of viruses with a wide host range, possessing a high capacity for adaptation in various climatic conditions and biological systems.

Viral particles can exist in plant cells in a latent form, gradually accumulating and causing systemic infection, which makes control efforts extremely challenging.

Transmission occurs through infected propagation material, seeds, and mechanically during agricultural operations (pruning, suckering), as well as via nematodes.

In addition to viruses, the term may be used to describe certain fungal infections that also produce concentric zonality on affected plant tissues.

The active development and spread of viral infection are triggered by warm, humid weather, which promotes high activity of insect vectors.

A crucial factor in dissemination is the presence of weeds in the field, which serve as natural reservoirs for the virus during the absence of the main agricultural crop.

Temperature ranges between 20–25 degrees Celsius are considered most favorable for the replication of viral particles and the expression of visible symptoms.

Failure to follow crop rotation practices and cultivating susceptible crops on the same site for several years significantly increases the soil's infection background.

The use of untested seed material that has not undergone phytosanitary control is the primary route for introducing pathogens into new territories.

The damage caused by ringspot disease consists of a sharp decline in the photosynthetic activity of plants, which inevitably leads to reduced yields.

Affected fruits lose their flavor, become unsuitable for long-term storage and transportation, resulting in direct economic losses.

In perennial crops, the virus can persist in overwintering tissues, gradually exhausting the plant and leading to its total death after several seasons of production.

Systemic infection lowers the crop's resistance to environmental stress factors, such as drought, temperature fluctuations, and secondary infections.

Infected stands require radical removal measures, increasing operational costs and necessitating additional investments in soil health restoration.

The foundation of protection is the use of exclusively certified, healthy propagation material that has been laboratory tested for the absence of viral infection.

• Regular destruction of weeds that serve as virus reservoirs;
• Control of insect vectors (aphids, nematodes, thrips) using insecticides;
• Maintenance of spatial isolation between new plantings and old infected areas;
• Disinfection of horticultural tools after working with each plant to prevent mechanical transmission of sap;
• Implementation of proper crop rotation, returning crops to the same location no sooner than after 3-4 years.

An important preventive measure is the removal and immediate burning of severely affected plant specimens to limit the spread of the infection throughout the field.

Developing immunity in varieties through breeding is the most promising long-term strategy, as there are no direct chemical treatments available for curing plant viruses.