EFFECT OF POPULATION-DYNAMICS OF PSEUDOMONAS-CEPACIA AND PAECILOMYCES-LILACINUS ON COLONIZATION OF POLYFOAM ROOTING CUBES BY RHIZOCTONIA-SOLANI

Suspensions of Pseudomonas cepacia (strain 5.5B) and Paecilomyces lila cinus (isolate 6.2F) were applied to polyfoam rooting cubes for contro l of stem rot of poinsettia caused by Rhizoctonia solani. The populati ons of antagonists and colonization of rooting cubes by R. solani were monitored during a 3-week period. Colonization of cubes by R. solani was reduced in cubes treated with P. cepacia, but the population of P. cepacia decreased by as much as 97% during the test period. Increased colonization by R. solani was correlated with a decline in population of P. cepacia. P. lilacinus was more persistent than P. cepacia in cu bes, with only a 21% reduction observed during the 3-week period. Colo nization of the P. lilacinus-treated cubes by R. solani was significan tly less than colonization of infested controls. No correlation existe d between population of P. lilacinus and colonization of cubes by R. s olani.