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Ministry of Agriculture, Food and Rural Affairs

Colour Disorders


Blotchy Ripening:  The tomato fruit appears mottled green, yellow, and red.  The flesh develops large patches of hard, grey to yellowish tissue that do not ripen.  When the fruit is cut open, brown strands of vascular tissue may be seen.  These symptoms may also be called grey wall.  Similar symptoms may be caused by virus infection.  Blotchy ripening is linked to boron or potassium deficiency, excessive nitrogen, high humidity, temperature fluctuations or extreme temperatures (cold, hot) in the later stages of ripening, high soil moisture levels, cloudy weather (low light levels) and soil compaction. It seems to be more common in high tunnel tomatoes than in the field. Varieties vary in susceptibility.

Internal White Tissue:  Although the exterior of the tomato may appear red, fruit with this disorder exhibit areas of hard, white tissue on the shoulders and/or in the core.  This is believed to be one variation of the yellow shoulder disorder.

Yellow Shoulder:  The tops of fruit do not ripen properly. It is thought to be triggered very shortly after fruit set.  The flesh on the fruit shoulders remains green (green shoulder) or turns yellow.  Yellow-eye is used to describe this disorder when only a ring of tissue around the stem scar is affected.  Varieties vary in susceptibility to these disorders; soil potassium and magnesium levels may be involved.  The disorder is initiated well before ripening and the areas will not ripen even if harvest is delayed. Exposure to intense sunlight can also cause yellow areas to develop on the fruit. This is because development of red colour is inhibited with fruit temperatures above 30°C. Although the air temperature may not reach this threshold, fruit surfaces exposed to direct sunlight can heat up above air temperature. See also Sunscald.

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