Unfortunately, not all tubers look nice coming out of the ground.
A new article by Andy Robinson, Associate Professor and Extension Potato Agronomist, North Dakota State University/University of Minnesota and Eugenia Banks, Potato Specialist, Ontario Potato Board discusses the causes of some of these problems.
Potato tubers are the result of the plant genetics and the environmental conditions in which they are grown. Potato varieties are selected carefully for tubers that have desirable appearance to maximize sales and reduce waste. However, some years can cause more environmental stress than others, resulting in tuber secondary growth. Secondary growth often manifests as heat sprouts, tuber chaining and tuber malformations. This physiological disorder decreases yield and quality of the tubers in the field.
