The critical period for fruit size was from petal fall for the next 28 days. Spur quality is higher in the top third of the canopy and decreases as one moves into the interior of the canopy. A study conducted in New Zealand on 'Granny Smith' indicated that fruits located above the limb were the largest whereas fruits bellow the limbs were the smallest. Since these patterns of changes in fruit size are closely followed by light levels found at the various canopy positions, it must follow that any pruning and or training techniques and or practices which increase light penetration will have an impact on fruit size. The supply of nutrients also controls positive fruit size.
Proper nutrition helps to maintain spur quality as well as fruit, vegetative and root growth.
Generally, high nitrogen fertilization results in larger fruit. However, this can in turn result in decreased fruit firmness. Therefore, nitrogen fertilization should be used cautiously.