The action of yeast strains as biocontrol agents against Penicillium digitatum in Lima sweet oranges
The green mold caused by Penicillium digitatum is the most important disease affecting citrus in the postharvest period. An alternative to control the disease lies on the use of yeasts. The purpose of the present study was to assess the ability of 101 yeasts strains to control P. digitatumin vitro and in vivo. The assay followed a randomized design with five repetitions and the evaluation took into consideration the mean pathogen colony diameter in Petri dish paired culture. In addition, the effect of the fungus on yeast strain growth was assessed. Orange fruits (Citrus sinensis cv. Lima) were injured in two equidistant points and inoculated with P. digitatum conidia suspension 24 hours before and after treatments, in the assays conducted in vivo. Treatments consisted in the application of eight yeast suspensions, fungicide and distilled water (control treatment); they followed a randomized design with three repetitions (20 fruits per repetition). The best antagonist results in vitro were recorded for five strains (Saccharomyces cerevisiae ACBL-76 and ACBL-82 strains; Candida stellimalicola ACBL-84 strain; and ACBL-87), which presented mycelial growth inhibition values higher than 80%. Two yeast strains (S. cerevisiae ACBL-82 strain and Meyerozyma caribbica ACBL-86 strain) have successfully controlled the progress and incidence of green mold in orange fruits when they were applied in a preventive manner.