40 Colorado Experiment Station 
common source of the trouble is from planting the potato in fields that 
have previously shown the disease within two or three years. Such 
soils are said to be ‘sick.’ 
“A second period of destruction due to this disease comes during 
storage. Tubers infected in the field when stored under conditions of 
Plate XIII. “Little potatoes’’ and “aerial tubers,’’ the former in a cluster beneath the 
soil surface, the latter on the stems above ground. 
