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WATERCORE: ITS RELATIONSHIP TO MEAN FRUIT SIZE AND CALCIUM CONCENTRATION AND RELEVANCE TO OTHER DISORDERS
Calcium concentrations are often, though not invariably, lower in individual fruits with watercore than in unaffected apples from the same source.
The disorder is more prevalent in samples of large average size, or high mean mass per apple which is usually inversely related to average calcium concentration.
In 1976 bulk samples of Cox’s Orange Pippin and Suntan apples were badly affected when their mean masses were higher than an unusually low (118 g) threshold and calcium concentrations were lower than 4 mg/100 g fresh matter.
In 1977 the same calcium threshold applied to Suntan fruit although the threshold for mean mass was much higher (180 g).
Thus watercore can indicate low calcium levels and if it is observed, fruit analyses should be made to check whether it is the type associated with low calcium concentration.
If so, other calcium-related disorders (i.e. lenticel blotch pit and breakdown with similar calcium thresholds, and bitter pit with a higher threshold) are likely to develop during storage before watercore symptoms have disappeared unless effective postharvest treatments are applied.