The saprophytic colonization and saprophytic suppression of the test organism of Fusarium oxysporum was studied in relation to soil moisture, pH and temperature. Survival of the pathogen increased when temperature was increased. The percentage survival of F. oxysporum in the pre-colonized paddy straw bits buried in soil was recorded. The fungal population was increased upto 75 per cent MHC. The competitive saprophytic colonization of the test organisms over paddy straw bits was favoured by 30% moisture. The acidic range of pH was favourable for the colonization of the substrate for the test organism.
