Postharvest Calcium Treatment of Apple Fruit to Provide Broad-Spectrum Protection Against Postharvest Pathogens. William S. Conway, Research Plant Pathologist, USDA-ARS, Horticultural Crops Quality Laboratory, BARC-West, Beltsville, MD 20705. Carl E. Sams, Judith A. Abbott, and Benny D. Bruton. Associate Professor, Department of Plant and Soil Science, University of Tennessee, Knoxville 37901; Research Horticulturalist, USDA-ARS, Instrumentation and Sensing Laboratory, BARC-East, Beltsville, MD 20705; and Research Plant Pathologist, USDA-ARS, Genetics and Production Research Laboratory, Lane, OK 74555. Plant Dis. 75:620-622. Accepted for publication 10 December 1990. 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, 1991. DOI: 10.1094/PD-75-0620.

Apple fruit (Malus domestica) were pressure infiltrated with calcium chloride solutions at harvest during three separate growing seasons. In 1984, the calcium concentration of Golden Delicious and Delicious apples ranged from 170 to 1,600 and 200 to 2,000 µg/g, respectively. In 1988, the calcium concentration of Delicious fruit ranged from 200 to 1,050 µg/g; similarly, that of Golden Delicious apples was 193–1,046 µg/g in 1989. Calcium concentration was negatively correlated with decay caused by the three different fungal pathogens tested during these three years. However, calcium reduced decay to a greater extent (70%) in fruit inoculated with Glomerella cingulata than in fruit inoculated with Penicillium expansum (37%) or Botrytis cinerea (50%). Thus, calcium-induced resistance to postharvest fungal pathogens is broad in spectrum.