19 



Table 2. Treatments applied to 20-kg allotments of soil. 



Soil Pathogen Natural 



Treatment fumigated w added* Antagonists 7 recolonization 2 * 



1 + weekly - + 



2 + weekly + + 



3 



+ 



initially 



4 



+ 



initially 



5 



+ 



initially 



6 



- 



initially 



N/A 



+ = soil fumigated with methyl bromide-chloropicrin (67/33% V A) at 

 1 kg of fumigant to 50 kg of soil for 2 days and then allowed to air 

 in the greenhouse for 4 days. 



- = soil not fumigated 



x weekly = Fusarium oxysporum f . sp. radicis-lycopersici was added at 

 1000 chlamydo spores per gram of soil to a 1500 g soil sample obtained 

 every 7 days for the duration of the experiment. 



initially = Fusarium oxysporum f . sp. radicis-lycopersici was added 

 to the entire soil allotment 4 days after fumigation at 1000 chlamydo- 

 spores per gram of soil. 



y+ = conidia of each of five antagonists (three isolates of Trichoderma 

 harzianum , one isolate of Penicillium restrictum , and one isolate of 

 Aspergillus ochraceus) added to the entire soil allotment at 1000 conidia 

 of each isolate per gram of soil 4 days after fumigation. 



-= antagonists not added. 

 z + = soils left uncovered to allow recolonization from naturally occur- 

 ring airborne inocula. 



- = soil placed in plastic containers to inhibit naturally occurring 

 recolonization . 



