Biocontrol of Erwinia carotovora on calla (Zantedeschia sp).

Abstract

Two studies were carried out to evaluate the antagonistic capacity of a B. subtilis strain against E. carotovora on calla. In study one, one substrate was infested with two levels of Erwinia and another was without infestation. After 24 hours, tubers of Zantedeschia sp, var. Lady Lack were planted (scalpel incised) on the substrate. For the second study, one level of infectation was used. Zantedeschia sp were planted and inoculated with 5 concentrations of the antagonistic strains. The first study was carried out under controlled conditions and the second one under greenhouse conditions.
Results of the first study showed that concentrations of antagonistic BC10 strains of B. subtilis at levels of 10⁴, 10⁶ and 10⁸ CFU/mL in the medium pathogen level showed a positive but not significant inhibiting capacity against E. carotovora. Concentrations of BC10 strains of 10¹⁴ CFU/mL interacted positively with E carotovora and increased the severity of the disease. Tubers were observed to be asymptomatic transmitters of the disease. In the second study, where wounds were not induced in the tubers, no differences between treatments were observed, with all plants showing normal development and a high percentage of survival.