Selected microbial strains suppress Phytophthora cryptogena in gerbera crops produced in open and closed soilless systems

Abstract

Several micro-organisms (Fusarium spp., Trichoderma spp., Oomycetes and bacteria) were isolated from the rhizosphere of gerbera plants grown in an open soilless system. Their capacity to suppress root rot caused by Phytophthora cryptogea was evaluated in 2000–2001 in three independent trials in open soilless systems. Different strains reduced disease incidence and/or increased flower production. The most effective strains (three of Fusarium and three of Trichoderma) were also tested in a closed soilless system in combination with slow sand filtration, in order to determine whether these two techniques together would be more effective in reducing P. cryptogea root rot. The results showed that slow sand filtration with antagonistic micro-organisms operated synergistically to significantly reduce disease incidence.