Common physiological disorders of potato foliage include frost, hail lightning, windburn, and air pollution damage. Damage from these disorders can be distributed uniformly across a field but may also occur in a pattern associated with a specific topographic feature such as a low spot or ridge. Foliar disorders are often mistaken for insect, disease, or herbicide damage. Tuber physiological disorders are usually not detected until after harvest, which makes it difficult to identify patterns of occurrence in the field. Physiological disorders are usually not detected until after harvest which makes it difficult to identify patterns of occurrence in the field. Physiological disorders reduce the marketability of tubers by damaging their appearance or reducing processing quality. In some cases, these defects also make the tubers more susceptible to decay.
Common disorders that produce symptoms on the outside of the tuber: include growth cracks, secondary growth (also called knobs, dumbbells, and malformed), heat sprouts, enlarged lenticels, and greening. Growth cracks and secondary.
Causes :
Growth is associated with non-uniform growing conditions. Heat sprouts are caused by high soil temperatures that cause the stolons to elongate and emerge from the soils. Lenticels may be enlarged when the tubers are exposed to very wet soil for prolonged periods. The tubers turn green in response to light exposure in the filed or after harvest.
Disorders that produce symptoms on the inside of tubers include :
Hollow heart, internal necrosis (also called heat necrosis and internal brown spot), sugar end (also called translucent end, dark end jelly end rot) and black-heart
Hollow heart (irregular cavity caused by rapid or irregular growth) is caused by non-uniform plant growth early in the development of tubers, especially when accompanied by cool, wet soil conditions and excessive nitrogen fertilisation. Internal necrosis or browning is associated with hot, dry weather and high soil temperatures during tuber bulking.
It is common on acid or phosphate deficient soils. Sugar end is associated with high soil temperatures and water stress during early tuber development. It most commonly occurs on the stolon end of the tuber and is not apparent until after processing. Blackheart (the black center of tuber) is caused when tubers are exposed to low oxygen conditions. Improper storage ventilation, high temperatures after harvest, or extended low temperatures in storage all favor black heart disorder.