Plant lactobacteriosis

The first visual sign of the disease is the appearance of localized softening areas that quickly become watery in consistency. The surface of affected fruits may slightly collapse inward due to the degradation of the internal parenchyma.

In the early stages, the epidermis may change color to a paler or yellowish hue. As the infection progresses, these affected areas darken, eventually turning brown or grayish-brown due to tissue death.

A characteristic symptom is a distinct sour smell emanating from the affected parts of the plant. This odor is caused by the intense lactic acid fermentation process occurring within the plant tissues under the influence of the bacteria.

• Formation of soft, watery spots on fruits and stems.
• Distinct sour odor in the infected area.
• Darkening and deformation of tissues.
• Rapid spread of rot under high humidity conditions.
• Suppression of vegetative growth and plant vitality.

When cutting into an affected fruit or stem, one may observe slimy secretions containing bacterial colonies. The internal tissue structure loses its turgor and resembles a loose, mushy mass.

The causative agent of the disease is bacteria of the genus Lactobacillus, specifically strains capable of facultative parasitism on plant tissues. While these microorganisms are typically associated with fermentation, modern research confirms their ability to colonize weakened plant tissues under certain conditions.

The disease is classified as a bacterial infection primarily affecting succulent tissues like fruits and stems. The pathogen enters the plant through natural openings such as stomata or through mechanical wounds caused by pests or agricultural equipment.

The bacteria secrete specific enzymes that break down pectin substances in plant cell walls. This enzymatic activity leads to the rapid softening of tissues and the loss of their overall structural integrity.

Lactobacillus desidiosus often acts as an opportunistic pathogen. Its development becomes possible when the plant's metabolic processes are disturbed due to environmental stress factors, making the plant susceptible to colonization.

The biology of the pathogen is closely tied to the accumulation of acidic metabolic byproducts. These acids further inhibit the vital functions of healthy plant cells, facilitating the spread of necrotic processes throughout the affected area.

The primary factor promoting disease development is high humidity in the air and soil. Excessive irrigation or prolonged rainfall creates a favorable microenvironment for bacterial multiplication on plant surfaces.

Temperature plays a crucial role, with the pathogen being most aggressive in the moderate to high temperature range of +20 to +28 degrees Celsius. Temperature fluctuations often lead to condensation, which facilitates bacterial colonization.

Mechanical injuries act as the entry points for the infection. Wounds caused by insect pests or agricultural tools significantly increase the probability of a lactobacteriosis outbreak.

Weakened plant immunity due to nutrient deficiencies or improper fertilization schedules makes plants highly vulnerable. Excessive nitrogen application is particularly dangerous, as it promotes rapid growth of soft, succulent tissues.

Plant residues left in the field after harvest contribute to the accumulation of the inoculum. Bacteria can survive in these residues until the next season, lying in wait for favorable environmental conditions to emerge.

Plant lactobacteriosis causes significant economic losses by damaging produce both in the field and during storage and transport. The resulting loss of visual quality makes the harvest unfit for commercial sale.

Infection of the stem can lead to the death of the entire plant as it disrupts the vascular system. This blockage prevents the proper transport of water and nutrients, resulting in rapid wilting and collapse.

The infection is characterized by high transmission rates within a population. Without localized control measures, a large portion of the crop can be lost in a very short period, particularly in greenhouse environments.

Infected produce is unsuitable for long-term storage because rot processes continue even at lower temperatures, leading to secondary losses in storage facilities.

The difficulty of early diagnosis adds to the harm, as growers often identify the issue too late to apply effective control measures, ultimately leading to substantial losses in total harvest yield.

Prevention starts with strict crop rotation and the thorough removal of all plant residues. Disinfecting tools used for plant maintenance is essential to prevent the spread of bacteria from infected to healthy plants.

Pest management is critical, as controlling insects reduces the number of wounds on the plant surface through which the pathogen can enter. Using insecticides is a vital component of integrated disease protection.

Managing irrigation schedules and ensuring proper greenhouse ventilation help reduce air humidity, creating conditions that are unfavorable for the multiplication of bacterial pathogens.

The application of biological products containing antagonistic microorganisms or specialized bactericides can be effective in the early stages of the disease. Following application instructions precisely is mandatory for success.

Balanced plant nutrition, particularly the supply of potassium and calcium, strengthens cell walls. This enhances the plant's resistance to the enzymatic degradation caused by bacterial pathogens.