Manganese deficiency

• Role in the plant: manganese is important chiefly for the process of photosynthesis and as a metabolic activator.

• Symptoms of deficiency: the young upper potato leaves have a dull green colour and show interveinal chlorosis with many small necrotic dots, localised mainly along the veins (photos 1 and 2). The plants are smaller, with necrotic areas on leaf margins (photo 2).

       Toxicity: excess of manganese, particularly in acidic soils, may cause the formation of pale green leaves and numerous necrotic spots on stems, petioles and can cover the entire leaf surface.