Marijuana Plant Deficiencies as stated by Ed Rosenthal, author of Growers Handbook

[Cannibalistixx]

Nitrogen - pale green leaves and then the withering and yellowing of the lowest leaves.

Phosphorus - small dark green leaves with red stems and red veins. Tips of lower leaves sometimes die. Eventually entire lower yellow leaves die.

Potassium - On sun leaves, necrotic patches on leaf tips and in patches throughout leaf. Leaves also look pale green. Old growth doesnt absorb nutrient and wont be affected.

Sulfur - new growth yellows and the entire plant pales. Use 1 tbsp/gal of epsom salt.

Magnesium - start on lower leaves which turn yellow leaving the vains green only. Growing shoots are pale green and if conditions worsen turn almost white.
Use 1 tbsp/gal of epsom salt.

Manganese - yellowing and dying of tissue between veins. use a Fe-Zn-Mn supplement.

[DierWolf]

All nice and dandy. If you educating us, would help to also mention the causes and fixes for the deficiencies.