Calcium is an element required by all higher plants in relatively large quantities. It appears to be closely related to the formation of buds and flowers.
Calcium is usually available in sufficient quantities in Kentucky soils to produce a normal crop of tobacco. However, when certain varieties of burley tobacco commence to bloom and produce suckers, the tips of the calyx lobes of the flowers may turn brown and die and the edges of the small leaves of the suckers may be necrotic, resulting in irregularly shaped sucker leaves. In severe cases the apical bud may be killed. These calcium deficiency symptoms are most often observed during periods of stress such as protracted dry periods. This condition has been found to be heritable and is apparently caused by the improper utilization by the plant rather than the lack of calcium in the soil.
Smiley, Jones H.; Massie, Ira E.; and Everette, George, "Calcium Deficiency Symptoms in Burley Tobacco" (1963). Agronomy Notes. 152.