Abstract: Hairy roots disease is an important problem in cultivation of greenhouse vegetables (tomato, aubergine and cucumber). Infection is caused by rhizogenic bacteria from Agrobacterium/Rhizobium group. It has been shown that infection process is regulated by environmental factors and quorum sensing mechanism. Rhizogenic bacteria produce acyl homoserine lactones (AHL) as signal molecules, which enable cell-to-cell communication. Disruption of this communication process will most likely lead to lower infection and symptoms. There are several possible routes of quorum quenching. One of them is degradation of pathogenic bacteria’s signal molecules by other microorganisms present in the root environment. Bacteria capable of AHL degradation were previously isolated from natural environment such as soil and water. In this research AHL degrading bacteria were successfully isolated from greenhouse growing substrate rockwool. Application of these micro-organisms in greenhouse practice is also discussed.