Growing Media Amended with Beneficial Microorganisms to Improve Growth Stimulation and Plant Protection

Plant diseases are a major cause of yield losses and ecosystem instability worldwide. Use of chemical pesticides to protect crop against plant pathogens has been increasing along with the intensification of production over the last decades. Nevertheless agrochemicals are often considered as one of the major pollution source of ground and surface water inducing depletion of freshwater. Beneficial microorganisms can offer a sustainable and efficient alternative to chemical pesticides used in agriculture. Extensive experiments have been done by Premier Tech Horticulture over the last years to select and combine different biocontrol agents use to protect plants against the major greenhouse diseases caused by Pythium spp., Rhizoctonia spp., Fusarium spp., Phythophtora spp. and Sclerotinia spp. Consequently, Bacillus subtillis, Bacillus pumilis and Mycorrhizae were amended in PRO-MIX® peat based growing medium. The aim of this communication is to present the most recent results supporting plant growth promotion and plant disease suppression effect of these different beneficial microorganisms. Several experiments were conducted on vegetables (tomato, lettuce, cucumber and pepper) and ornamental plants (celosia, geranium, pansy, petunia, begonia and vinca). Data obtained in these studies demonstrated that in absence of biocontrol agents, the shoot and root weight of plants were negatively affected by pathogens infestation. In case of disease presence, the health of the root and shoot systems was the most important parameter. The presence of beneficial microorganisms in the substrates results in the best fresh or dry root and shoots systems.