Postharvest Biology and Technology 45 (2007) 326–332 Control of blue mold of apple by combining controlled atmosphere, an antagonist mixture, and sodium bicarbonate William S. Conway a,∗ , Wojciech J. Janisiewicz b , Britta Leverentz a , Robert A. Saftner a , Mary J. Camp c a Produce Quality and Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, United States b Appalachian Fruit Research Station, Agricultural Research Service, U.S. Department of Agriculture, 45 Wiltshire Road, Kearneysville, WV 25430, United States c Biometrical Consulting Service, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, United States Received 20 October 2006; accepted 11 March 2007 Abstract ‘Golden Delicious’ apples were wound-inoculated with Penicillium expansum and treated with various combinations of sodium bicarbonate and two antagonists (Metschnikowia pulcherrima, Cryptococcus laurentii), and then stored in air or controlled atmosphere (CA = 1.4 kPa O 2 and 3 kPa CO 2 ) for 2 or 4 months at 1 ◦ C. The antagonists survived and their populations increased during both air and CA storage. The antagonists alone reduced blue mold but were more effective when combined. Sodium bicarbonate tended to reduce lesion size when used with these antagonist, either when they were used alone or combined. Storage under CA conditions also increased the effectiveness of both antagonist, when used alone or in combination. The only treatment that completely eliminated P. expansum-incited decay was the combination of the two antagonists and sodium bicarbonate on fruit stored under CA conditions. The proper combination of alternative control measures can provide commercially acceptable long-term control of fruit decay and could help reduce our dependency on fungicides. © 2007 Elsevier B.V. All rights reserved. Keywords: Metschnikowia pulcherrima; Cryptococcus laurentii; Postharvest biocontrol; Integrated control 1. Introduction In a 2003 survey (http://www.foodnews.org/walletguide.php) on pesticide contamination of fresh produce, fruit topped the list of the consistently most contaminated foods and apples were the fourth most contaminated produce item. There is an increas- ing concern in the scientific community about the subtle ways that small doses of pesticides may have chronic adverse effects on people (Ragsdale and Sisler, 1994). Fungicides have been the most effective means of controlling postharvest diseases on fruit for many years. However, restrictions on the use of fungi- cides (Ragsdale and Sisler, 1994) due to the aforementioned concerns about their effects on human health and the continu- ing development of resistance in postharvest pathogens to the ∗ Corresponding author at: USDA, ARS, B-002, Rm 117, 10300 Baltimore Avenue, Beltsville, MD 20705-2350, United States. Tel.: +1 301 504 6980; fax: +1 301 504 5107. E-mail address: Conwayw@ba.ars.usda.gov (W.S. Conway). commonly used fungicides such as benzimidazole and dicar- boximide (Lennox and Spotts, 2003), makes it of paramount importance to find alternatives to the use of fungicides to reduce losses from postharvest decays. Alternative control methods alone do not have as wide a spectrum of activity under vari- ous conditions as fungicides and most of them cannot achieve the effectiveness of fungicides even under optimal conditions. Therefore, a combination of promising alternatives must be used to develop a control strategy suitable for commercial application. Biological control is an alternative to chemical control that shows effectiveness in controlling postharvest diseases (Janisiewicz et al., 2001; Janisiewicz and Jeffers, 1997; Korsten et al., 1994; Usall et al., 2001; Wilson and Wisniewski, 1989; Zhou et al., 2001). Gray mold and blue mold decay of apples and pears, caused by Botrytis cinerea and Penicillium expan- sum, respectively, have been controlled by bacterial and yeast antagonists (Chand-Goyal and Spotts, 1996; Janisiewicz, 1994; Janisiewicz and Marchi, 1992; Roberts, 1990). Postharvest dis- eases of stone, citrus, and subtropical fruit have also been 0925-5214/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.postharvbio.2007.03.005