blossom end rott

Plants affected
Tomatoes and related crops such as aubergines and peppers.

Symptoms
Light brown spots appear at the flower end of the fruit. Eventually these form a dark brown sunken ring, giving the fruit a flattened appearance.

Cause
This is not a disease, but a disorder caused by lack of calcium to the plant, due to an inadequate or intermittent water supply. If the growing medium is allowed to dry out, the roots are unable to absorb nutrients effectively. A similar problem can also arise if fertiliser is added to dry soil, because the nutrients are too concentrated for absorption by the plant.

Treatment
The potting medium should be kept consistently moist throughout the growing season. It is better to water twice a day than once with a double volume.

A liquid fertiliser may also help, but must only be applied to moist soil.

If this disorder is treated early, later fruit should provide a good crop.