Tuber External Growth Defects: LITTLE TUBER DISORDER

When many tubers form off the seed piece before sprout emergence, the disorder is called little tuber disorder. Small tubers develop at the same time as the seed piece sprouts. This disorder will affect plant growth and reduce yields.

Development and Appearance

Little tuber disorderLittle tuber disorder develops in storage due to aging of seed tubers. Upon planting little tubers are initiated directly at the eyes of the seed piece or on very short stolons while the seed piece is sprouting. This can also occur in storage prior to planting. Physiologically, it is induced by a break down of apical dominance of the eyes on the tuber and of sprouts on the stolons. The mechanism is similar to that for tuber chaining.


This disorder is due to physiological aging of seed tubers as a response to high late-season storage temperature. It occurs when seed piece temperature is greater than 68oF and is planted in soil that is less than 50oF. Little tuber disorder can also occur when sprouted seed tubers or pieces are placed in cold storage and then planted. Elevated concentrations of the gases carbon dioxide (CO2) and ethylene (C2H4), a gaseous hormone, may induce little tuber disorder as well as be involved in tuber chaining and heat sprouting. All of these disorders are due to changes in hormone levels.


No difference in varietal sensitivity to this has been reported although there are varietal differences in reaching the stages of physiological aging.

Cultural Practices

Since the disorder is caused by seed tuber aging in warm storages, the key practice is storing seed potatoes at less than 40oF, but above temperatures causing chilling or freezing damage (NPE 11-4, 1999). Avoid long storage of seed tubers. Avoid physiologically aging seed such as rough handling (bruising), poor ventilation or elevated temperatures. Do not plant in cold (<50oF), dry (<60% FC) soil.