Postharvest biological control of grey mold and blue mold on apple by Cryptococcus albidus (Saito) Skinner

The yeast Cryprococcus albidus (Saito) Skinner, an antagonist isolated from peach fruit, was evaluated for biological control capability in 'Fuji' apple after challenge with 1x10(5) or 5 x 10(4) spores/ml of the postharvest pathogens Botrytis cinerea and Penicillium expansum. The yeast at 1 x 10(8) CFU/ml of washed cells suspension totally inhibited decay in apple fruits at 23 and 1 degreesC. The concentrations of antagonist and pathogen spores had significant effects on biocontrol effectiveness. Culture filtrate of the yeast failed to provide protection against the two pathogens. The antagonist was compatible with iprodione and calcium chloride. The yeast at 1x10(6) CFU/ml mixed with iprodione at 50 ppm a.i. provided better control of decay than the single application. Calcium chloride facilitated control of B. cinerea and P. expansum by C. albidus at a concentration as low as 10(5) CFU/ml. Rapid colonisation of apples from wounds was observed by the first 48 h at both 23 and 1 degreesC. This stabilised at the same density thereafter at 23 degreesC, but was lower at 1 degreesC. Efficacy of C. albidus against B. cinerea and P. expansum was maintained when it was applied before the pathogens, but was reduced when applied simultaneously with or after the spores. (C) 2001 Elsevier Science B.V. All rights reserved.