Potato growers are familiar with the expression ‘a potato storage is not a hospital’, which reflects the simple truth that diseased potatoes going into storage are not going to get better. It is essential that growers carefully monitor potatoes going into storage and keep a close eye on storage conditions to keep infections from spreading to maintain the value of their crop. It’s also important to understand that managing potato diseases in storage is both an art and a science. The top five storage diseases that require continuous vigilance during the storage period are: late blight, pink rot, Pythium leak, fusarium and dry rot.

Late Blight: External tuber symptoms appear as slightly sunken, brown to purplish areas of variable size. The flesh has a reddish or tan/brown, dry, granular rot that extends from the skin of the tuber inward an inch or more. Tissues with late blight are firm to the touch, not wet or mushy.

Pink Rot: Infected areas of the tuber surface are purplish-black. The flesh first appears cream colored, when sliced open, a salmon-pink coloration develops after 15 to 20 minutes at room temperature. The affected flesh has a rubbery, “boiled potato” consistency. A distinct line separates healthy and infected tissue. Pink rot in storage is usually accompanied by a distinctive ammonia odor.

Pythium Leak: External tuber lesions are grey with a water-soaked appearance. The flesh is brown/grey to black; with time it turns inky black. When affected tubers are squeezed, a clear liquid is readily released by the rotted tissue.

Fusarium Dry Rot: Dark depressions develop on the surface of the tuber. The skin becomes wrinkled in concentric rings as the underlying dead tissue desiccates. Internal symptoms are characterized by dry, necrotic tissue shaded from light to dark brown or black.  Rotted cavities are often lined with mycelia and spores of various colors from yellow to white to pink. Infected tubers eventually shrivel and mummify.

Correct Identification of each of these diseases is critical to apply post-harvest treatments and to implement specific storage management practices. Harvesting, handling and storing problem potatoes require continuous attention.

Content Source: https://spudsmart.com/top-5-storage-diseases/

Image source: https://www.extension.uidaho.edu/publishing/pdf/CIS/CIS1131.pdf