Dark spots or pits on the skin of the fruits and small brown blotches spread through the flesh.
- Bitter pit is caused by calcium deficiency.
- In most cases, the soil has enough calcium, however it is not always available to be taken up by plants.
- Levels of other nutrients such as potassium and magnesium can affect calcium availability.
- Other factors which play a part include, soil acidity and moisture levels.
- On acid soils, steps can be used to raise the pH to an ideal level of around 6.5. pH testing kits are widely available and the level can be raised by adding lime to the soil. This can be a long process and the benefits of liming can be slow to appear.
- Avoid using high potash (potassium) feeds. Although these are known to encourage flowering and fruiting, they can also reduce the availability of calcium in the soil.
- Mulch with bulky materials which improve soil structure, such as home made compost or leaf mould.
- Sprays containing calcium chloride or calcium carbonate can be applied directly to the fruits. These are often marketed as treatments for blossom end rot.
- Original Article here