37 

 control is to establish a community which is inhibitory to the pathogen 



in the treated soil. Fusarium oxysporum f. sp. radicis-lycopersici is 

 an r-selected species, as indicated by the rapid increase and then 

 decrease of its population density in the absence of other organisms; 

 therefore , its ability to compete as a saprophyte is dependent upon the 

 total propagule density of all interacting microorganisms in the soil 

 (22). The saprophytic proliferation of the pathogen was controlled by 

 adding r-selected antagonists to freshly fumigated soil before the re- 

 invasion of the pathogen could occur. By the application of the basic 

 concepts of community ecology to the control of plant disease and the 

 utilization of composites of antagonists, the success of biological 

 control investigations may increase, and disease control in the field 

 may be realized more frequently. 



