Nutrients

P Phosphorus
K Potassium
Mg Magnesium
Ca Calcium
S Sulfur
B Boron
Fe Iron
Mn Manganese
Zn Zinc

Apples - Chlorosis

Symptoms
Old leaves bluish-green with scorched margins (brown or grey). Margins may first appear light green and later turn necrotic. Necrosis progresses from the margins inward to the midrib.

Reasons
Potassium deficiency Frost and drought can cause similar symptoms

Apples - Necrosis

Symptoms
Old leaves bluish-green with scorched margins (brown or grey). Margins may first appear light green and later turn necrotic. Necrosis progresses from the margins inward to the midrib.

Reasons
Potassium deficiency Frost and drought can cause similar symptoms

Potassium deficiency made worse by

  • Acidic soils (low pH)
  • Sandy or light soils (leaching)
  • Drought conditions
  • High rainfall (leaching)
  • or heavy irrigation
  • Heavy clay (illite) soils
  • Soils with low K reserves
  • Magnesium rich soils

Potassium is important for

  • New growth is healthy
  • Cold hardiness is improved
  • Flower number increases
  • Fruit are longer and are generally more intensely coloured
  • Fruit may mature earlier and have improved flavour
  • Yields are increased