Biocontrol of Postharvest Diseases of Jujube Fruit by Cryptococcus laurentii Combined with a Low Dosage of Fungicides Under Different Storage Conditions.

An antagonistic yeast, Cryptococcus laurentii, alone or in combination with a low dose of imazalil (25 μg a.i./ml) or kresoxim-methyl (50 μg a.i./ml), was investigated for its ability to control Alternaria alternata and Monilinia fructicola on jujube fruit under different storage conditions. Biocontrol activity of C. laurentii against A. alternata and M. fructicola at 20°C was enhanced significantly by combination with either fungicide. An integrated strategy for control of A. alternata and M. fructicola was developed that included a combination of C. laurentii, a low dose of fungicide, and controlled-atmosphere (CA) storage. Fruit treated with C. laurentii plus imazalil at 25 μg a.i./ml or kresoxim-methyl at 50 μg a.i./ml and stored in CA storage with 10% O₂ + 0% CO₂ at 0°C showed a lower disease incidence caused by both pathogens than fruit stored in air at 0°C. Application of imazalil (25 μg a.i./ml) or kresoxim-methyl (50 μg a.i./ml) did not inhibit the growth of C. laurentii in wounds of jujube fruit stored in air at 20 and 0°C or in CA at 0°C. The yeast grew rapidly in the wounds of jujube fruit under all storage conditions. The ability of C. laurentii to effectively control postharvest diseases of jujube fruit, the resistance of C. laurentii to low rates of fungicides, and the adaptability of this yeast to CA storage indicate that C. laurentii has great commercial potential as a biological control product.