Efficacy of preharvest and postharvest Candida sake biocontrol treatments to prevent blue mould on apples during cold storage

This study compared the biocontrol efficiency of preharvest and postharvest applied yeast cells of Candida sake to apples (cv. Golden Delicious) wound ed before and after harvest and inoculated with Penicillium expansum prior to cold storage conditions in two seasons, 1994/95 and 1995/96. The establi shment of populations of C. sake during this period also was determined. In both years, postharvest treatment with the antagonist resulted in signific ant (P < 0.05) and effective control of Penicillium rot whether pre- or pos tharvest wounds were made. Maximum disease control achieved, in terms of in cidence and severity, was greater than 80% reduction in lesion diameter and 50% reduction in the incidence of lesions. However, preharvest application of the antagonistic yeast at a concentration of 3 . 10(6) CFU/ml was less effective against Penicillium rot than postharvest treatment. No advantages in biocontrol were observed when apples were treated with the yeast antago nist both pre- and postharvest. Candida sake population levels during cold storage of apples receiving only preharvest application of the antagonist d ecreased prior and more rapidly than levels in apples receiving a postharve st application. High populations of C. sake were present in postharvest-tre ated apples, even after 90 days in cold storage. (C) 1999 Elsevier Science B.V. All rights reserved.