| Abstract: | Establishment and survival of two biocontrol agents, the yeast Pichia guilermondii isolate Y2, and one of two isolates of the bacterium Bacillus mycoides (B16 and B17), were studied in commercial-like greenhouse experiments. The establishment of the biocontrol agents and their survival on strawberry leaflets and fruitlets were recorded in two experiments. Bacterial populations and their rate of decline over time did not differ significantly when applied alone or in a mixture with the yeast. In most cases, the results were similar for the yeast, but in two out of 27 comparisons the yeast populations, when applied in a mixture with the bacterium, were significantly larger than when applied separately. The biocontrol activity of the yeast and the bacterium against Botrytis cinerea on strawberry plants was examined in two experiments. In one experiment, the biocontrol agents reduced the number of diseased fruits by 50% when applied alone, whereas their mixture resulted in a 75% disease reduction. In this case, the effect of the biocontrol agnets in the mixture was additive. In a second experiment, the same yeast isolate and the other bacterial isolate (B17) were combined. The biocontrol agents did not significantly reduce the disease when applied separately. However, their mixture resulted in a synergistic effect and disease suppression was significantly improved compared to the biocontrol agents applied alone. |
