Symptoms are ofton mistaken for those of potassium deficiency. Blades of recently matured leaves become chlorotic, then turn to a pronounced yellow with scorching of the interveinal tissues. Necrotic spots form within these areas and gradually expand to include most of the interveinal tissues except for a green triangular area near the base of the leaf. This characteristic shape of an arrowhead or letter "A" is unique to magnesium deficiency. The necrotic areas tend to be a lighter brown than for potassium deficiency, and at first they often appear as a netted, white veining. A green freckling, accompanied by leaf deformation, often occurs when the plants are young.