SECTION III 

 BIOLOGICAL CONTROL OF FUSARIUM CROWN 

 ROT OF TOMATO UNDER FIELD CONDITIONS 



Introduction 



Fusarium crown rot of tomato was first reported in south Florida 

 during the 197^—1975 growing season (33)- Attempts to control the 

 disease with chemicals and host resistance have been unsuccessful (2?). 

 At present, the only effective control measure is the application of a 

 captafol drench to greenhouse "beds immediately after steaming (2?). The 

 captafol drench selectively inhibits recolonization of the soil by the 

 pathogen, Fusarium oxysporum Schlecht f . sp. radicis-lyconersici Jarvis 

 and Shoemaker (15). When captafol was applied as a preplant or post- 

 plant drench to the transplant hole under south Florida field conditions, 

 the estimated yield was slightly higher, but there was a 1 wk delay in 

 plant maturation (3*0 • Furthermore, a complete soil drench of the entire 

 bed is not practical to tomato production in south Florida because a 

 plastic mulch is maintained during the entire growing season. 



The possibility of obtaining disease control with biological agents 

 was investigated. It was hypothesized that if selected soil antagonists 

 could decrease the rapid saprophytic development of the pathogen during 

 the early stages of soil recolonization, less infection would occur and 

 the severity of the epidemic would be reduced. In growth- chamber and 

 greenhouse experiments, infection incidence and mean lesion length on 

 tomato plants were reduced when antagonists were added to fumigated soil 



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