Nitrogen

Deficient apple leaves are pale green to yellow.

Color develops uniformly on the leaf with no patterning or mottling, and leaf size is small.

Potassium Deficiencies result initially in a yellowing of tissue along leaf margins.

That tissue later turns a bronze color and may eventually die, producing a scorched zone along the edges of      leaves as the deficiency progresses.

Magnesium

Inadequate Mg causes a yellowing of tissue along leaf margins and between the main veins.

Symptoms may initially develop along leaf margins, similar to K deficiency symptoms

Boron

Inadequate B results in a reduction in leaf size.

New shoot growth is severely reduced, and shoot tips may die back in severe cases.

Manganese

Symptoms are similar to those of Mg deficiency, but they appear first on young leaves.

Youngest leaves yellow between the veins.

Zinc

Leaves are much smaller than normal and narrow.

The tissue between the main veins turns yellow and chlorotic.

Calcium

Bitter pit associated with localized deficiency of calcium in apple fruit.

Lesions typically concentrated towards the calix end of fruit.

Iron

Iron deficient leaves showing bleached appearance on youngest leaves, and necrotic margins