Soft rot, caused by pectolytic bacteria, especially from the genus Pectobacterium, is one of the most significant diseases of lettuce, causing significant crop losses. Due to limitations on the use of chemical pesticides and their limited efficacy, the development of biological control methods, including those based on Bacillus subtilis, has become an urgent issue.

The aim of this study was to evaluate the efficacy of various B. subtilis-based preparations in controlling wet rot in greenhouse lettuce production. The experiment was conducted during the spring and summer of 2025, and involved artificially infecting plants with predominant local Pectobacterium species and then treating them with liquid formulations of Bacillus subtilis. The efficacy of treatment was compared under different application frequencies and intervals. To assess the biological effects, a comprehensive evaluation of the plant condition was carried out based on the following parameters: the severity of rot symptoms, the rate of spread and radius of infection, the length and weight of roots and leaves, and the survival of plants 7, 14, and 21 days after infection.

Various strains of B. subtilis demonstrated high antagonistic activity against Pectobacterium-caused infection, particularly when integrated with specific agricultural techniques. The combined use of microbial preparations and agricultural techniques that promote the activity of these antagonists can be an effective and environmentally friendly alternative to traditional chemical methods of protection.