IN VITRO CONTROL OF FUSARIUM WILT USING AGROINDUSTRIAL SUBPRODUCTBASED COMPOSTS
F. Suárez-Estrella, M.A. Bustamante, R. Moral, M.C. Vargas-García, M.J. López, J. Moreno
Some kinds of compost suppress soil-borne plant pathogens and although their exact mode of action is not yet clear, several mechanisms seem to be involved in the supressive effect. The abiotic component of compost is an important factor for its suppressive effect in soils, however it must be kept in mind that compost is considered a source of biocontrol agents against several serious plant pathogens. The main aim of this work was to discriminate the biotic and abiotic components in agroindustrial subproduct-based composts that could be potentially used as suppressive soil amendments. Results have shown that the compost’s suppressive effect on mycelial development of Fusarium oxysporum f. sp. melonis (FOM), the causal agent of Fusarium wilt of melon, was due to a combination of biotic and abiotic factors. Similar results were observed when compost extracts were used against the pathogenic fungus. In this case, compost extracts with a concentration between 0.1 and 50% inhibited FOM growth. However, sterilized compost extracts inhibited fungal development when applied at a dose lower than 10%, while higher concentrations (>10%) were not effective, probably due to the toxic substances and nutrient content ratio in the culture media. This can be indicative of a masking of the inhibitory effect at high nutritional levels. Based on these results, we conclude that the suppressive effect of compost is due to a combination of biotic and abiotic factors, though the former are mainly responsible for the biocontrol activity against FOM.