Suppression of the plant diseases, Pythium (damping-off), Rhizoctonia (root rot) and Verticillium (wilt) by vermicomposts

Vermicomposts are stabilized, non-thermophilic materials produced from organic wastes by interactions between earthworms and microorganisms. Suppression of Pythium by vermicomposts was tested by substituting 0, 10, 20 and 40% of vermicomposts (by volume) into 100, 90, 80 and 60% of a soil-less plant growth medium Metro Mix 360 (MM360), inoculated with Pythium at a rate of 1:4000 by volume. Disease severity was rated after 10 days, from I (symptomless) to 4 (heavy). The disease severity rating was 3.4 in 0% vermicompost substitution, compared with 1.1 in 10% substitution, 1.3 in 20% substitution, and 1.1 in 40% substitution. A similar range of substitutions of sterilized or non-sterilized MM360 and vermicompost was tested in three experiments with radish seeds inoculated with 1:2000 or 1:667 by volume of Rhizoctonia. Suppression of Rhizoctonia by vermicomposts was correlated progressively with increasing rates of substitution of vermicompost in three experiments. In field experiments planted with strawberries, the incidence of Verticillium wilt was suppressed significantly by the application of 5 t/ha and 10 t/ha of commercial paper and food waste vermicomposts.