Fruit Surface Colonization and Biological Control of Postharvest Diseases of Pear by Preharvest Yeast Applications

The yeasts Cryptococcus infirmo-miniatus, Cryptococcus laurentii, and Rhodotorula glutinis, applied to Bosc and d'Anjou pear fruit in the field 3 weeks prior to harvest, maintained high population levels through harvest, while populations of Candida oleophila declined after 1 and 2 weeks, and by harvest were not significantly different from total yeast populations on untreated fruit. Yeasts were sprayed individually on fruit at concentrations of 1 to 3 × 10⁸ CFU/ml, with approximately 2 ml applied per fruit. Initial population sizes for all four species averaged 5 × 10⁶ CFU per fruit. C. infirmo-miniatus provided the most consistent decay control in fruit treated 3 weeks before harvest. C. infirmo-miniatus and R. glutinis also provided significant postharvest decay control in Bosc fruit treated 1 day before harvest.