Thermales

The biological cycle of the pathogen is directly dependent on temperature conditions, which is how this group of lesions received its name. The fungal mycelium penetrates the vascular system of the plant, disrupting its metabolism.

The spores of the pathogen are capable of surviving in the soil substrate and on plant debris for extended periods. This makes the infection extremely resistant to standard greenhouse cleaning procedures.

The spread of conidia occurs mainly through air droplets during ventilation or via contaminated gardening tools. Secondary infection may occur if planting density is high.

The pathogen displays high aggressiveness during periods of plant overheating, as the natural immunity of the crop is weakened by thermal stress.

The primary symptom of infection is the appearance of specific chlorotic spots on leaf blades, which quickly turn brown. Eventually, the tissue at the site of the infection loses turgor and dies off.

Upon closer inspection of the leaf undersides, one can observe a thin, spiderweb-like coating, indicating fungal sporulation. This coating has a characteristic grayish shade that distinguishes Thermales from other diseases.

Elongated lesions or necrotic patches often appear on the stems of affected plants, eventually leading to constrictions. This restricts the flow of water and nutrients to the growth points.

In advanced cases, the disease spreads to the fruits, causing deformation and premature drop. The commercial value of the crop is lost almost entirely within a few days.

A critical sign is the wilting of the upper part of the plant during the day, which does not recover after heavy watering, indicating damage to the vascular ring.

The development of the disease is triggered by consistently high temperatures (above 28-30 degrees Celsius) combined with high relative humidity.

Poor circulation of air masses in greenhouses creates "dead zones" where spore concentration reaches maximum levels. Lack of ventilation is the primary catalyst for the disease spread.

Plant overcrowding and high density prevent normal heating and drying of the foliage, creating a favorable environment for spore germination.

Overhead irrigation, sometimes used during hot weather to cool plants, often leads to wet foliage, providing the fungus with the moisture required for infection initiation.

Improper fertilization practices, particularly an excess of nitrogen, make plant tissues more succulent and susceptible to mycelial penetration.

The damage caused by Thermales lies in a sharp decline in photosynthetic activity, which leads to stunted growth and development of the crop.

Damage to the vascular system leads to systemic wilting, which can destroy up to 60-80% of greenhouse yields within a short period.

The quality of the harvested produce decreases significantly: fruits become small, lose flavor, and have an extremely low shelf life during transport.

Economic losses include not only the direct reduction in yield but also the need for full substrate disinfection after infection hotspots are detected.

The infection can result in the complete culling of seedlings if localization measures are delayed.

The priority measure is strict adherence to greenhouse temperature regulation, including the use of shading and effective ventilation systems.

Preventive soil substrate treatment before planting using biological fungicides significantly lowers the risk of primary infection.

• Regular removal and disposal of infected plant debris away from the site.
• Disinfection of gardening tools with specialized solutions after each work cycle.
• Maintaining optimal planting density to ensure proper airflow.

Upon detecting the first symptoms, spot treatment with systemic chemical fungicides approved for the specific crop must be carried out.

Organizing a proper root-zone irrigation regime that prevents water droplets from hitting the above-ground parts of the plant is a critical step in protection.