The suppressiveness of Finnish light coloured Sphagnum peat

Half of the Sphagnum peat lots used as the substrate significantly reduced or inhibited damping-off caused by Alternaria brassicicola Wiltshire, Plenodomus lingam (Tode ex Fr.) Höhnel and Rhizoctonia solani Kühn on cauliflowers. New peat slowed down the spread of Fusarium oxysporum Schl. f. sp. lycopersici (Sacc.) Snyder & Hansen from infected tomato plants to healthy ones and development of the disease on infected seedlings in comparison to disinfected peat. When new peat was added to disinfected peat the suppressing effect was regained. The most common microbes in the peat were bacteria, Streptomyces spp., followed by fungi, Penicillium spp., Mortierella spp. and Trichoderma viride Pers. ex Fr. Strepromyces spp. and T. viride effectively inhibited the growth of a number of soil and seedborne fungi on a nutrient medium. Treating the peat or seeds with T. viride and Streptomyces spp, isolates inhibited or reduced damping-off caused by A. brassicicola, P. lingam and R. solani on cauliflower growing on the peat substrate