50 

 as a saprophyte during the early stages of recolonization. The applica- 

 tion of antagonists in these types of disease situations should be 

 successful in controlling the diseases, if the antagonists are properly 

 selected and administered. 



In this study, the success of the biological control agents was 

 dependent upon several factors. The severity of an epidemic of Fusarium 

 crown rot of tomato is dependent upon the rapid proliferation of the 

 pathogen in treated soils (28). When the antagonists were applied to 

 soils before recolonization by the pathogen could occur, they were able 

 to effectively occupy the niche space created by the fumigation proce- 

 dures (Section II) . The preoccupied niche space then was rendered 

 unavailable to the pathogen. The decrease in the saprophytic develop- 

 ment of the pathogen was due to its inability to compete in soils recol- 

 onized by antagonists. Severe disease expression requires infection of 

 the host early in the season (15), therefore, antagonists need to be 

 established mainly around the crown and roots of the transplant. 

 Successful control of Fusarium crown rot of tomato with biological 

 agents was dependent upon production practices , the biology of the path- 

 ogen, and the methods used for selection and application of the antago- 

 nists. 



