Diseases
Bitter pit: dark spots on fruit
A calcium-related fruit disorder that shows up late or in storage, and how to reduce it.
Relevant stages: Fruit Development I, Fruit Development II, Fruit Development III, Pre-Harvest.
Bitter pit shows as small, dark, sunken spots on the skin with dry, brown flesh underneath. It often appears late in the season or in storage.
What causes it
- Low calcium in the fruit. Usually the soil has enough. The tree struggles to move calcium into the fruit.
- Uneven water supply, especially dry spells followed by heavy watering or rain.
- Too much nitrogen, potassium or magnesium, and very vigorous trees with light crops.
How to reduce it
- Follow the calcium chloride sprays (3 to 4 g per litre) at fruit development I, II and III and at pre-harvest, as in the SKUAST guide.
- Keep soil moisture steady with mulch and regular irrigation.
- Do not over-feed nitrogen.
- Balance the crop load with thinning.
Calcium sprays reduce bitter pit but do not remove it completely, so good watering and balanced nutrition matter as much.
General guidance. Always read product labels and consult an agronomist for problems specific to your orchard.
