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The 17 essential elements
are:
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Calcium (Ca)
Form used by plants:
Ca2+
Important functions:
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Important in cell wall and membrane construction
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Regulates nutrient uptake by roots and movement in plant
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Necessary for development of firm fruit
Ideal foliage range for apple leaves:
1.2-1.6% (However, do not rely on leaf analysis to identify Ca deficiency). Vegetative growth out competes fruit for available Ca.
Ideal fruit concentration:
0.01-0.03% of dry weight (fruit flesh)
Ideal soil range:
600-4000 ppm
Calcium is strongly sorbed by soil components and thus not mobile.
Best indicators:
Fruit analysis- observe fruit for bitter pit (see photo below) or cork spot. May see premature shedding of blossoms and buds.
Mobility in plant:
Not remobilized within plant
Deficiency symptoms: 
Fruits have a low ability to attract Ca and instead it is utilized by growing shoots and leaves.
Fruit symptoms: bitter pit (see photo), cork spot, senescent breakdown, watercore. Maturity will be hastened (if not monitored, may lead to significant drop and poor storageability).
Increased risk of Ca deficiencies on:
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Overfertilized plots (excess Mg or K in soil makes it more difficult for roots to take up Ca; too much N stimulates vegetative growth which will take Ca away from fruit)
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Excessively pruned plots (due to stimulation of vegetation)
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Areas with B deficiencies because this may reduce calcium movement
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Excessively large fruit should be avoided
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Water-stressed areas or areas subject to wide fluctuations in moisture supply
Excess problems/Interactions with other elements:
*see increased risk section above
Updated
July 13, 2004
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