Paenibacillus

The genus Paenibacillus consists of soil-borne Gram-positive rod-shaped microorganisms. While many members of this genus act as beneficial biocontrol agents, certain species, including specific strains of Paenibacillus polymyxa, can exhibit phytopathogenic traits, leading to bacteriosis, tissue rotting, and damage to the vascular system of cultivated plants.

This pathogen typically affects vegetables, cereals, and industrial crops. The bacteria pose the greatest threat to root vegetables, causing soft rot, and to seedlings in greenhouse environments, which often leads to significant crop loss due to damage in the root zone and stems.

Common symptoms of infection include the appearance of water-soaked spots on plant tissues, the development of wet rot, a foul odor at the site of infection, and stunted growth. In cases of systemic infection, nutrient transport is severely impaired, resulting in wilting leaves and the eventual death of vegetative plant organs.

Infection development is favored by high soil and air humidity, along with temperatures in the 20–28°C range. The pathogen spreads primarily through contaminated seeds or planting material, soil, plant debris, and farm machinery, where the bacteria can persist for long periods in the form of dormant spores.

The economic impact of Paenibacillus is significant due to the rapid destruction of plant tissues; without proper control, losses can reach 40-60% of the harvest. Management strategies include rigorous crop rotation, greenhouse disinfection, the use of certified healthy planting material, and the application of biological treatments based on antagonistic bacterial strains.