What Are the Causes of Stone Burn in Apricots?

Heat

• Pit burn defect, or PD, occurs when the temperature reaches more than 100 degrees F before harvesting the fruit. PD develops during the period between the fruit starting to lose its green color and being ripe enough to pluck. The softening of the flesh around the stone gets ripe faster than the rest of the fruit, but the outside of the fruit shows no sign of damage. If pit burn reaches an advanced stage, the apricot may become rotten.

Drought

• Keeping the apricots moist during a dry season will help cool the plant. Apricots grow best in mild climates similar to the Mediterranean, with little frost during spring and few very hot days. They flourish in fertile, well-drained soil and need protection and cooling during hot, dry weather.

Resistance

• Potassium-based fertilizers make the plants less susceptible to pit burn defect. Some varieties are more likely to develop PD than others, such as Blenheim, Wenatchee, Moorpark and Autumn Royal. Modesto, Patterson, Helena, Tri Gem and Tilton, however, are some of the varieties that are better able to resist the condition.

Prevention

• Prevent pit burn defect by planting apricots in regions where the temperature rarely reaches in the triple-digits. Keep the soil moist and well-drained, and spray the trees with water to cool them on hot days. Use fertilizers high in nitrogen as sparingly as possible, as high nitrogen content can make PD more likely to occur.