The pathogen FOM was isolated from infected muskmelon plants from a greenhouse nursery. Conidia were recovered as described by Blaya et al. (2013). The trays were moistened periodically by manual watering, following the normal nursery routine. Finally, the seedlings were harvested 40 days after being transplanted, for measurement of the fresh weight of their aerial parts. Also, the seedlings inoculated with FOM were weighed and the suppressive effect of the composts was evaluated. The effect of F. oxysporum was estimated as the percentage fresh weight loss of the melon plants grown on a medium (treatment) infected with F. oxysporum with respect to the same medium without inoculation of the phytopathogen ( López-Mondéjar et al., 2012).