Calcium deficiency (plant disorder)

Calcium (Ca) deficiency is a common disorder of plants on acidic soils, but more usually caused by unavailability rather than a shortage. This may be due to water shortages, which slow the transportation of calcium to the plant, or can be caused by excessive usage of potassium or nitrogen fertilisers.

Symptoms include curling of young leaves or shoots and poor growth. Crop-specific symptoms include:


 * Apple : 'Bitter pit' – fruit skins develop pits, brown patches appear in flesh and taste becomes bitter. Can occur when fruit is in storage. Bramley apples are particularly susceptible.
 * Cabbage and Brussels sprouts : Internal browning.
 * Carrot : 'Cavity spot' – oval spots develop into craters which may be invaded by other disease causing organisms.
 * Celery : Stunted growth, central leaves stunted.
 * Tomatoes and peppers : 'Blossom end rot' – Symptoms start as sunken, dry decaying areas at the blossom end of the fruit, furthest away from the stem, not all fruit on a truss is necessarily affected. Sometimes rapid growth from high-nitrogen fertilizers may cause blossom end rot.

Calcium deficiency can be rectified by adding Agricultural lime to acid soils, aiming at a pH of 6.5, unless the plant in question specifically prefers acidic soil. Organic matter should be added to the soil in order to improve its moisture-retaining capacity.

Calcium deficiency symptoms appear initially as generally stunted plant growth, necrotic leaf margins on young leaves, and eventual death of terminal buds and root tips. Plant damage is difficult to reverse, so take corrective action immediately. Make supplemental applications of calcium nitrate at 200 ppm nitrogen. Test and correct the pH if needed because calcium deficiency is often associated with low pH.