EVALUATION OF ANTAGONISTIC STRAINS OF FUSARIUM SPP IN THE BIOLOGICAL AND INTEGRATED CONTROL OF FUSARIUM-WILT OF CYCLAMEN

The ability of antagonistic strains of Fusarium spp, to control Fusarium wilt of cyclamen caused by Fusarium oxysporum f. sp. cyclaminis was tested under glasshouse conditions over three years. Several antagonistic strains of F. oxysporum and one strain of F. moniliforme, applied alone or in mixtures, were able to decrease significantly (p = 0.05) the incidence of Fusarium wilt. Biological control was consistent especially when the antagonists were applied both by mixing a chlamydospore talc preparation in the potting substrate (3 x 10(4) - 5 x 10(5) CFU/ml of soil) two weeks before transplant and by dipping plant roots at transplant in a conidial suspension (1 x 10(7) - 5 x 10(8) CFU/ml). The combination of the benzimidazole fungicide carbendazim and antagonistic Fusarium spp. generally increased the efficacy of control. Carbendazim (0.5 mg a.i./ml pf substrate) proved most effective in reducing or delaying the appearance of Fusarium wilt symptoms when the dosage was split into two applications, one at transplant and one 2 months later. Sodium alginate and kaolin formulations of F. oxysporum antagonistic strain 251/2 were not effective in reducing Fusarium wilt on cyclamen, while the same strain applied as chlamydospores dispersed in talc or as conidial suspension controlled the pathogen. The findings are discussed with respect to the most effective application and formulation methods of biocontrol agents under commercial conditions.