Flexibacteriosis

The primary external manifestation of the disease is the rapid softening of the plant's affected tissues. In the early stages, watery spots appear on leaves or stems, which quickly darken and expand in size.

As the infection progresses, the affected areas begin to emit a specific unpleasant odor characteristic of decay. The tissues turn into a mushy mass, making any further vegetative growth of the damaged area impossible.

When the root system or root crops are affected, their total destruction is observed. On cross-sections, degradation of the vascular system is clearly visible, often acquiring a brown or dark color due to clogging by bacterial mass.

Often, in high-humidity conditions, a bacterial exudate appears on the surface of damaged tissues in the form of droplets or a slimy film. This secretion contains billions of active bacterial cells ready for further spread.

Visually, the disease is often confused with other types of soft rots, but flexibacteriosis is distinguished by a higher rate of cellulose destruction. The plant can die within a few days after the appearance of the first visible infection centers.

The causative agent of the disease is gram-negative rod-shaped bacteria belonging to the order Flexibacteriales. These microorganisms possess pronounced motility due to gliding movement, which distinguishes them from many other plant pathogens.

They are obligate or facultative saprophytes capable of surviving for a long time in plant debris and soil substrate. The bacteria produce a powerful complex of enzymes that break down pectin substances in cell walls.

Microorganisms of this order are often found in aquatic ecosystems and moist soils, which determines their ability to attack plants with high water content. The high activity of their enzymatic apparatus allows them to penetrate deep into the plant through the smallest mechanical injuries.

The biology of Flexibacteriales includes the formation of complex colonies that create a protective mucous barrier. This factor significantly complicates the effect of antibacterial drugs on the pathogen under natural conditions.

Intracellular development and reproduction occur primarily in intercellular spaces, where bacteria actively feed on cell sap and tissue decay products. Thanks to rapid division, the pathogen population reaches critical levels in a very short time.

A critical factor for the onset of an epiphytotic is a high level of relative humidity, exceeding 85-90 percent. Prolonged rainfall or excessive overhead irrigation promotes the rapid spread of the infection.

A temperature range of +20 to +28 degrees Celsius is considered most favorable for the active metabolism of Flexibacteriales. At lower temperatures, bacterial activity decreases, but they do not die, entering a state of dormancy.

The presence of free moisture on the plant surface is a mandatory condition for the movement of bacteria from an infected plant to a healthy one. Moisture serves as a transport medium for the mobile cells of the pathogen.

Mechanical injuries received during plant care, harvesting, or due to pest activity open direct gates for infection entry. Any wound on a plant becomes a primary infection site.

Dense planting and the lack of proper ventilation in greenhouses create a microclimate that maximally promotes the establishment and spread of the pathogen. Under these conditions, spores and bacterial cells concentrate, creating a high infection load.

The main damage caused by flexibacteriosis consists of the total loss of marketability of produce and the rapid death of plant vegetative organs. Yields in affected areas can decrease by 50-100 percent in a short period of time.

Bacterial infection leads to the disruption of metabolism and photosynthetic activity. The plant loses the ability to transport water and nutrients, which causes systemic wilting and subsequent necrosis.

The infection poses a serious threat during storage, as contaminated produce can spread the disease to the entire batch in the storage facility, leading to mass rotting processes in warehouses.

Contamination of the soil with the pathogen excludes the possibility of growing susceptible crops in that area for several years. This forces agronomists to change crop rotation and implement expensive soil disinfection methods.

Economic damage consists not only of direct yield loss but also of expenses for additional protective measures and the forced culling of products before sale.

The basis of control is strict adherence to phytosanitary rules: the removal and destruction of all plant debris affected by the pathogen. Burning or deep burial of residues significantly lowers the infectious background.

An important technique is the implementation of rational crop rotation using plants that are not hosts for these bacteria. This breaks the pathogen's development cycle and reduces the likelihood of re-infection.

Using drip irrigation instead of overhead watering minimizes the humidity of leaves and stems, limiting the paths of infection spread. Microclimate control in greenhouses is a key success factor.

Preventive spraying with copper-based preparations allows for creating a protective barrier on the plant surface. However, such methods are effective only in the early stages or as a preventive measure before symptoms appear.

The use of resistant varieties and hybrids is the most promising method, although breeding for this trait is currently limited. It is also recommended to disinfect agricultural tools after every operation to prevent the mechanical transfer of bacteria.