Bitter pit

Bitter pit, often referred to as Apple dimple or apple scar, is a severe physiological disorder affecting fruit trees. It is primarily caused by a localized calcium deficiency in the fruit tissues, which triggers cell degradation and the formation of characteristic pitted areas.

The primary crop affected by this condition is the domestic apple (Malus domestica). While the disease does not spread between trees like a fungal infection, its impact on fruit quality, storage shelf life, and marketability makes it a significant concern for commercial orchardists.

Symptoms appear as small, circular, slightly depressed spots on the surface of the fruit skin. These pits are often darker or greener than the surrounding skin. Upon cutting the fruit, the underlying flesh appears brownish, dry, and spongy, possessing a distinctly bitter flavor, which explains the common name.

Conditions that promote the development of bitter pit include high vigor of the tree leading to competition for calcium, excessive nitrogen fertilization, and fluctuating irrigation levels. Fruit that grows too rapidly or is excessively large due to low crop loads is significantly more susceptible to this disorder.

Effective management and prevention strategies include:

• Regular foliar applications of calcium sprays during the fruit development stage.
• Maintaining soil moisture consistency to ensure steady nutrient uptake.
• Pruning practices that prevent excessive vegetative growth that competes with fruits for calcium.
• Careful monitoring of nitrogen and potassium levels in the soil to maintain nutrient balance.