Apple Bitter Pit: A Common Disorder and How to Manage It
What is Apple Bitter Pit?
Apple bitter pit is a disorder that affects apples, causing brown, corky spots to develop in the flesh of the fruit. It is not caused by a fungus, bacteria, or virus, but rather by a lack of calcium in the fruit. Calcium is essential for the proper development of apples, and when there is not enough calcium, the fruit can develop bitter pit.
Symptoms of Apple Bitter Pit
The symptoms of apple bitter pit are small, brown spots on the skin of the apple. These spots are usually about 1/4 inch (6 mm) across and may be slightly sunken. As the disorder progresses, the spots may become larger and more numerous. The flesh beneath the spots is also affected, becoming brown and corky.
Causes of Apple Bitter Pit
Apple bitter pit is caused by a lack of calcium in the fruit. Calcium is essential for the proper development of apples, and when there is not enough calcium, the fruit can develop bitter pit. There are several factors that can contribute to a lack of calcium in apples, including:
- Poor soil drainage
- Drought stress
- Excessive nitrogen fertilization
- Heavy pruning
- Certain apple varieties are more susceptible to bitter pit than others.
Management of Apple Bitter Pit
There are several things you can do to manage apple bitter pit in your orchard:
- Improve soil drainage. Poor soil drainage can lead to waterlogged soil, which can make it difficult for apple trees to absorb calcium. If your soil is poorly drained, you can improve drainage by installing drainage tiles or raised beds.
- Avoid drought stress. Drought stress can also lead to a lack of calcium in apples. Water your apple trees regularly, especially during hot, dry weather.
- Fertilize your trees appropriately. Excessive nitrogen fertilization can contribute to bitter pit. Fertilize your apple trees according to the soil test recommendations.
- Prune your trees judiciously. Heavy pruning can lead to excessive shoot growth, which can compete with fruit for calcium. Prune your apple trees only when necessary, and avoid pruning them too heavily.
- Choose resistant varieties. Some apple varieties are more resistant to bitter pit than others. If you are having problems with bitter pit, consider planting resistant varieties.
Conclusion
Apple bitter pit is a common disorder that can affect apples. By understanding the causes of bitter pit and implementing the management practices described above, you can reduce the incidence of this disorder in your orchard.