Low Calcium status affects rapidly expanding tissue such as new leaves, roots and developing fruit. Meristems fail to expand and growing points become necrotic. Leaf scorch, tip burn and blossom end rot are classic symptoms of low calcium status, all of which are worse during conditions that promote rapid growth.
As mobility within the plant is very low, calcium demand can readily exceed supply, creating stress can restrict leaf, root and fruit development. As calcium is only taken up by a very small fraction of new roots, anything that restricts root development will affect calcium uptake.
Check soil calcium status and correct if necessary. Maintain plant phosphorous and zinc level to optimise root development and calcium uptake. Foliar feed with calcium during periods of heat or moisture stress.