Cork spot is a serious physiological disorder in pear (Pyruscommunis L. cv. d'Anjou) in the United States, but a reliable technique for diagnosing it has not been developed. A review of the scientific literature indicated the disorder was generally linked with low calcium concentration in the fruit. In the present study, mineral analyses were conducted in 1987 and 1988 on soil, leaves, and fruit peel from normal trees and trees prone to cork spot. Soil tests and leaf analysis did not provide measureable differences between the two groups of trees. Fruit analysis provided variable differences between normal and cork spotted fruit, but no single nutrient or ration of nutrients could be consistently associated with the disorder. An assay for pyruvate kinase was evaluated as a diagnostic tool for cork spot. The assay did not provide measureable differences between normal and cork spotted fruit. An important finding of this study was to learn cork spotted fruit had higher soluble protein concentration than normal fruit.
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