The use of biosurfactants is a promising alternative in biological control of zoospore-producing plant pathogens. In the present study, biosurfactant production by the indigenous population of fluorescent pseudomonads in a soilless plant cultivation system was studied during the growing season. A total of 600 strains was screened and of these 18.5% were observed to produce biosurfactants. Production of both antibiotics and biosurfactant was uncommon among the isolated strains. A selective effect of the cultivation system filter was observed on the biosurfactant-producing strains and these strains were only occasionally observed after the filter, despite having a significantly higher motility than the nonbiosurfactant-producing strains. The majority of biosurfactant-producing strains were isolated from the filter skin, which suggests that this is a suitable surface for inoculation with biocontrol strains.