Characterization of biocontrol activity of two yeast strains from Uruguay against blue mold of apple

Abstract

In the present study, two yeast antagonists, Cryptococcus laurentii (strain 317) and Candida ciferrii (strain 283) isolated from the surface of healthy apples, controlled blue mold of apple caused by Penicillium expansum. Both antagonists reduced the incidence of blue mold by 80% at 25 °C. At 5 °C C. ciferrii (strain 283) maintained the efficacy of disease control, but C. laurentii (strain 317) only reduced disease incidence by 50%. Moreover C. ciferrii (strain 283) exhibited significant protection at lower concentrations than C. laurentii (strain 317). The population of both strains increased in wounds of apples at 25 and 5 °C, and both strains maintained viable over a period of 35 days at 5 °C. Nutrient competition into wounds appeared to be the principal mode of action of these antagonists. Nitrogen rather than carbon appeared to be the limiting factor to both the antagonists and the pathogen. Further research will explore commercial potential of these antagonists and the possibility of enhancing biocontrol efficacy by using mixtures of antagonists or addtives such as calcium chloride or deoxyglucose.