Rain and cold delayed potato harvest throughout Wisconsin in the US in 2018. Many farms were still digging potatoes in late October and into November. Temperatures below freezing took a toll on numerous fields when potatoes suffered frost damage.
No one wants to see another harvest like 2018, but perhaps there is value in reviewing the causes and consequences of frost damage and discussing strategies for managing frost-damaged potatoes.
Frost damage occurs when tuber temperature drops below approximately 30 degrees Fahrenheit and tuber tissues freeze. Potatoes that are closer to the surface are more likely to experience freezing temperatures than those deeper in the soil. Green potatoes, which are at the soil surface, will undoubtedly be the first to suffer from frost damage.
Frozen potato tissue is no longer viable and cannot be healed. Rapid water loss begins as soon as the affected tubers thaw. Frost-damaged tissues develop wet patches on the skin as moisture leaks from lenticels.
Strategies for managing frost-damaged potatoes are based on conventional best practices for storing potatoes.
Once a decision has been made to store frost-damaged potatoes, the storage manager needs to establish priorities for stabilizing the stored material and delivering a saleable product. The highest priority should be maintaining the quality of potatoes that have not been frozen.