Tuber Internal Growth Defects: INTERNAL HEAT NECROSIS

Heat necrosis in potatoInternal heat necrosis is associated most with high temperatures at harvest, acid soils and low calcium. Most affected are certain chipping varieties most notably Atlantic. Low soil moisture may have a role.

External Appearance:

There is no outer appearance change. Reports have indicated that spindly sprouts may form from affected seed pieces.

Diagnostic Method:

Cut transverse, cross-sectionally, through center and at bud end.

Internal Appearance:

The necrosis appears as light tan, dark yellow to reddish brown flecks or specks; these may be dark brown or black in the most severe cases. They resemble the necrosis seen with chilling injury. Flecks usually cluster near the center toward the bud end and can appear similar to blackheart. The flecks are firm; there's no breakdown or rot. Vascular tissue is usually not affected but, in some cases, flecks may be confined to the vascular tissue at the bud end.

Cooking Appearance:

Flecks fry brown. Fries and chips will be speckled around their center.


This disorder is initiated as a result of harvesting during high temperatures and develops in storage over the first few months. Tubers near the ground surface are most affected. Heat necrosis is most common during hot and dry seasons and with potatoes planted in light soils. Low tuber calcium has been correlated with this disorder; whether a cause or result isn't clear.

Control Measures:

  1. Add lime to acid soils.
  2. Add of calcium to deficient soils.
  3. Establish good vine growth to shade ground (row closure).
  4. Don't store tubers in ground long after vine death.
  5. Schedule irrigation for seasonal growth.