Lahmiales

Initial symptoms appear as small chlorotic spots on the leaf blade. Over time, these spots increase in size and take on a characteristic coloration.

A key sign is the presence of necrotic zones with a distinct border. In the center of the affected areas, one can often observe the fruit bodies of the fungus.

As the disease progresses, premature yellowing and shedding of the lower leaves are observed. The plant noticeably lags behind healthy specimens in growth.

In conditions of high humidity, a faint coating consisting of the pathogen's spores forms on the underside of the leaf. Stems may take on a brownish hue.

Upon visual inspection of the fields, affected patches stand out. Plants look stunted, deformed, and lose turgor during the hot hours of the day.

The causative agent of this disease is a fungus from the Lahmiales genus. It is a highly specialized pathogen that primarily infects plant tissues in specific climatic zones.

Biologically, the fungus belongs to the Ascomycota group. It is capable of maintaining its viability in plant debris for a long time by entering a dormant stage.

The pathogen's life cycle is closely linked to seasonal changes in temperature and humidity. The dispersal of spores occurs mainly through airborne transmission or rain splashes.

The fungal mycelium penetrates the plant epidermis, gradually destroying the cell wall structure. During its life cycle, the pathogen actively releases specific enzymes.

An important aspect of its pathogenicity is the fungus's ability to adapt to fungicidal agents if they are applied incorrectly or unsystematically in agricultural practices.

The favorable environment for the rapid spread of the disease is high air humidity exceeding 75–80%. The pathogen becomes active during prolonged rainy periods.

The optimal temperature for mycelial growth is between +18 and +24 degrees Celsius. Rapid temperature fluctuations can trigger the release of spores.

Violation of crop rotation and returning a susceptible crop to the same plot sooner than every 3-4 years drastically increases the probability of epiphytotic outbreaks.

Thickened crops, where ventilation is impeded, create a "greenhouse effect" in the lower canopy, which significantly facilitates spore penetration into plant tissues.

The presence of weeds in inter-row spaces contributes to maintaining the infectious background. Weeds often act as intermediate hosts for fungal pathogens.

Lahmiales poses a serious threat to yields as it causes massive damage to the assimilative surface of the leaves, reducing the intensity of photosynthesis.

In the case of early infection, the death of young shoots is possible. This leads to sparse stands and the need for reseeding on significant areas.

The quality of the harvested produce significantly deteriorates. Damaged plant parts lose their marketability, which is critical for fruit and vegetable crops.

Severe infection leads to a decrease in plant immunity, paving the way for secondary infections. This significantly complicates accurate diagnosis.

Economic losses consist of the costs of fungicide treatments and lost harvests. In years of severe outbreaks, losses can reach up to 40% of the total yield.

The basis of protection is the use of resistant varieties and hybrids, as well as adherence to scientifically sound crop rotation. It is the most effective prevention method.

It is important to timely carry out deep plowing with the incorporation of post-harvest residues. This deprives the pathogen of a substrate for overwintering.

Upon the appearance of the first signs of the disease, systemic fungicides must be applied according to regulations. Alternating active ingredients is recommended.

• Regular monitoring of fields for symptom presence.
• Optimization of plant stand density to improve ventilation.
• Timely control of reservoir weeds.

Balanced fertilization with potassium and phosphorus increases the natural resistance of plants to this fungal disease.