Symptoms of Manganese toxicity are nothing but the deficiency symptoms of the following elements

When Manganese is present in toxic concentration, Mn competes with Iron and Magnesium during absorption of minerals. It also competes with the Mg for binding with the enzymes. Mn inhibits the translocation of Calcium in shoot apex. Hence Mn toxicity symptoms are nothing but deficiency symptoms for Fe, Mg and Calcium as deficiency of these three elements cause chlorosis and necrosis, the leaves develop brown spots (necrosis) surrounded by chlorotic veins.