Symptoms start on younger leaves, which fail to expand properly. Ca deficiency creates "spike leaf" appearance with the lamina of young leaves being deformed or absent. Thickening of secondary veins, accompanied by marginal chlorosis.
Extreme deficiency may cause leaf drop and die-off.
Roots can be shortened, thickened, and necrotic.
Calcium deficiency.
Danger of confusion: Boron and calcium deficiency both lead to necrosis on the upper leaves. The colour of the necrosis is a lighter brown with Ca undersupply, and the necrosis then starts from the leaf tip, not from the leaf margin. Both nutrient deficiencies cause thickening of secondary veins, but it is more pronounced when Ca is lacking.
Symptoms of B and Ca deficiency can easily be confused with virus diseases or herbicide damage as well.
Leaf analysis is therefore recommended.