Managing purpling of maize leaves
Even though some maize varieties have a natural purple pigmentation and low temperatures can disturb the plant's metabolism, leading to similar symptoms, purpling of maize leaver can be caused by nutrient deficiency.
Leaf tissues should be tested to ensure a correct diagnosis.
Phosphorus
A dark green colour on the leaves and steam, with purplish edges, probably due to anthocyanin accumulation, indicates a phosphorus deficiency. Symptoms are worst when soils are wet and cold.
Magnesium
Deficiencies occur first on older leaves which develop a yellow or white interveinal chlorosis. At later stages, leaves may become reddish-purple and in severe cases leaf tips and edges may die.
Magnesium deficiency can result of an imbalance with potassium. Leaf tissue analysis is recommended as Mg and K deficiency symptoms are similar.
