symptoms:
when foliar symptoms occur they are most common at young leaf or shoot tips, which may be curled inward or ragged, scorched and killed.
apple: fruit, the most common symptom is bitter pit, dark spots or pits on the surface with brownish spots beneath and also scattered throughout the flesh-bramley's seedling is highly prone (but you know that!). other symptoms on apples include glassiness, lenticel spotting and death of fruit tissues when stored under low temperatures.
physiology:calcium is relatively immobile in tissues, not moving readily from old to new leaves, which therefore display the 'starved' symptoms. it's a vital component of cell walls, essential for functioning of growing points and root growth.
excess potassium, magnesium and ammonium-nitrogen in the soil decrease the availability of calcium to plants. other limiting factors of availability are water stress and high humidity.
nearly there.........