Control of Storage Decay of Apples with Sporobolomyces roseus . W. J. JANISIEWICZ, Agricultural Research Service, U.S. Department of Agriculture, Appalachian Fruit Research Station, 45 Wiltshire Road, Kearneysville, WV 25430. D. L. PETERSON, and R. BORS, Agricultural Research Service, U.S. Department of Agriculture, Appalachian Fruit Research Station, 45 Wiltshire Road, Kearneysville, WV 25430. Plant Dis. 78:466-470. Accepted for publication 2 February 1994. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1994. DOI: 10.1094/PD-78-0466.

The biocontrol potential of an antagonist occurring naturally on pome fruit surfaces against postharvesl diseases of apple (Malus ? domestica) was investigated. Pink yeast, Sporobolomyces roseus (isolate FS-43-238), isolated from pear fruit reduced blue mold (Penicillium expansum) from 100 to 0% and gray mold (Bolrytis cinerea) from 78 to 0% on wounded fruit drop-inoculated with suspensions containing 7.9 ? 106 and 6.3 ? 105 cfu/ml yeast cells, respectively, and then challenged with the pathogen at 104 conidia per milliliter. The reduction in the percentage of infected wounds and in average lesion diameter followed a similar pattern and was effected by the antagonist and pathogen concentrations. On wounded apples dipped in the pathogen or antagonist-pathogen suspensions and stored for 3 mo at 1°C, the incidence of rots was reduced from 33 to 0% for P. expansum and from 92 to 4% for B. cinerea at yeast concentrations of 7.9 and 5.3 x 106 cfu/ml, respectively. In spray application, where S. roseus was mixed with both pathogens (each at 104 conidia per milliliter), less than 1% of fruit developed lesions in the antagonist-pathogen treatment, compared to 15% in the control and 9% in the thiabendazole treatment, after 6 mo in storage at 1°C. Wounds were readily colonized by S. roseus, and the populations increased from 4.3 to 6.1 log cfu/ml in drop-application experiments after 48 hr at 18°C and from 4.1 to 6.4 log cfu/ml in spray-application experiments after 3 mo at 1°C. In addition to its effectiveness at relatively low concentrations, S. roseus shows promise for commercial development because it is ubiquitous in nature, occurs commonly on fruits, and does not grow at 36°C.

Keyword(s): postharvest biocontrol