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PI-009: Seed Potato Tuber Inspection
Appendix 12: Defects not Scorable

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Enlarged Lenticels

Excessive moisture before harvest is the main cause of this disorder. Normally, lenticels are inconspicuous on tubers but under high moisture conditions they rise about 1/16 inch (1.6 mm) and form numerous whitish protuberances over the tuber surface.  If tubers are held in moist atmospheres, these elevated areas remain whitish, but when the tuber dries, they become skin colored, open and somewhat depressed.  They make excellent openings for micro-organisms, particularly soft rot bacteria.

Enlarged lenticels are not scored as a defect in seed potatoes unless associated with disease caused by other pathogenic organisms.

86 | Enlarged lenticels
86 | Enlarged lenticels. Description follows.
Description for 86

This image of a potato demonstrates an example of enlarged lenticels. The potato has a light-yellow and light-brown skin. It is covered in a multitude of brown spots. These brown spots are the enlarged lenticels and they cover the entire potato.

87 | Healed Over Flesh
87 | Healed Over Flesh. Description follows.
Description for 87

This image of a potato demonstrates an example of healed over flesh. The potato has a flaky, peeling, white skin that covers the entire potato. The healed skin beneath the flakes that has become exposed from the peeling is a creamy brown colour.

Healed Over Flesh

Occasionally, potatoes are harvested without allowing sufficient time for the skins to set. As a result, the skin of affected potatoes may be damaged and through time will heal and a second skin will develop.  This is sometimes called "healed over flesh".

Affected potatoes will have areas that are either darker or lighter brown than the normal skin color.  This could materially or seriously affect the potato's appearance. This type of discolouration usually affects only the skin area and not the flesh portion of the potato or the viability of the eyes of seed potato tubers.

Healed over flesh is not scoreable for seed potatoes.


Scald usually results from a rapid loss of moisture through skinned areas and oxidation of immature potatoes.  Frequently, the tissue exposed by feathering that has not healed over is scalded and turns dark. Affected tubers turn green or yellow more readily and may be badly shriveled.  Frequently rot develops even where no further change in the surface is apparent. In many cases, the affected area becomes sunken and is usually followed by a wet rot.

Scald is not scored on its own, but may be classified either as soft rot, dry rot, or scored as tubers not firm when applicable.

88 | Scald
88 | Scald. Description follows.
Description for 88

This image of a potato demonstrates an example of scald.The potato has a yellow skin, with the scald appearing in different places on the potato. The scald on this potato takes the form of several dark-brown spots covers 50% of the visible part of the tuber.

89 | Scald
89 | Scald. Description follows.
Description for 89

This image of a potato demonstrates an example of scald. The potato has a yellow and light-brown skin, with the majority of the scald occurring on its right side. The scald on this potato takes the form of several moderately-sized dark-brown spots. There are three larger visible spots on the side of the potato that is viewed, each taking up 5% or less of surface area of the visible side.

Hollow Heart

Hollow heart is a condition brought about by too rapid or too irregular growth.  It often occurs during wet seasons in very fertile or heavily irrigated soils.  Hollow heart consists of more or less irregular cavities of varying size within the potato and is usually lined with light-brown to brown dead tissue.  This defect is usually, but not always found, in large, rough, misshapen potatoes.  The potato should be cut lengthwise, parallel to the flat side, to determine the defect.  If the potato is not cut lengthwise, the hollow heart may not be detected.

Hollow heart may be associated with other malformations of tubers and shall be culled appropriately.  Where tubers appear normal and sound and no breakdown occurs, hollow heart is not scored.  However, when hollow heart is associated with decay, it is scored under the appropriate category.

90 | Hollow heart
90 | Hollow heart. Description follows.
Description for 90

This image of a potato demonstrates an example of hollow heart. The image is of a red-skinned potato that has been cut in half, showing a hole that has formed inside the potato symmetrically on both halves. The hollow hole in this image is an irregular shape with slightly jagged edges, and is a light-brown colour. The hole takes up 10% of the cut surface area in each half of the potato.

91 | Hollow heart
91 | Hollow heart. Description follows.
Description for 91

This image of a potato demonstrates an example of hollow heart. The image is of a red-skinned potato that has been cut in half, showing a small hole that has formed in the potato symmetrically on both halves. The hole takes the form of a small slit that is slightly gaping open, and is of a light-brown colour. It takes up less than 5% of the cut surface area in each half of the potato.

Silver Scurf

Silver Scurf, caused by Helminthosporium solani, is characterized by a grey, smooth, leathery appearance of the skin and is more noticeable when tubers are wet because of a characteristic silvery sheen.  This silvery condition is caused by a fungus that penetrates the tubers through the lenticels and skin. After prolonged storage under warm and moist conditions, the tubers look sooty or smudgy. The disease may spread in storage, especially under high humidity and temperatures.

Silver Scurf is not scored on it own but it is scoreable under Damage when the surface is so badly wrinkled, shriveled, or pitted that it seriously affects the germination quality of the potato. When the underlying flesh is dry or corky and affects more than 10% of the surface area of the tuber, Silver Scurf is scored as dry rot.

92 | Silver scurf
92 | Silver scurf. Description follows.
Description for 92

This image of two potatoes demonstrates and example of silver scurf. Both potatoes have a light yellow skin with light-brown patches. They are characterized as having silver scurf because they have a grey, smooth, moist, leathery appearance.


The presence of any live larvae or insects should be recorded.  Make note if the insects are either live or dead when found.

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