Calcium deficiency (Blossom end rot) — Tomato

Symptoms

Symptoms commonly appear on the first fruit clusters, although the disorder can occur at different growth stages. Light-brown patches develop at the blossom end of young fruits that are at least one-third developed. The patches gradually darken and develop into sunken, black, leathery areas. The affected tissue is dry and firm. The damaged area may extend over as much as half of the fruit. Internal blackening may be visible when the fruit is cut open. Secondary organisms may invade the dead tissue, resulting in soft fruit rot.