Scald

Symptoms

• Irregular brown patches of dead skin which can become rough when severe, developing within 3 to 7 days upon warming of the fruit following cold storage.
• The warm temperatures do not cause the scald but allow symptoms to develop from previous injury which occurred during cold storage.
• Symptoms may be visible in cold storage when injury is severe. In this case, the symptoms intensify upon warming the fruit.
• Scald is usually not evident until after 3 months of storage. Storage scald can involve only the skin or extend 6 mm (¼-inch) into the flesh depending on the variety.
• Scald can be more severe on the greener side of the fruit.

Control

• Today, the most common method used to control scald is application of an antioxidant immediately after harvest.
• Diphenylamine (DPA) is commonly used. Ethoxyquin is also effective for some varieties, but can cause damage to some apple varieties (check labels for recommendations).
• Antioxidants should be applied within one week of harvest for maximum control. Wait 16 hours after DPA application before cooling of fruit (unless bitter pit is of great concern as cooling delays can increase bitter pit incidence).
• Low oxygen-controlled atmosphere storage can provide a non-chemical control method in some cases.
• Oxygen concentrations between 0.5 and 1.0% can significantly delay the development of scald, perhaps up to 10 months.
• Fruit tolerance to such low oxygen levels as well as their effectiveness for scald control must be tested prior to use.