Why do some apples have more than one colour?

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Q. Have you ever heard of a bi-coloured apple? I spotted one in a grocery store bin of ordinary red apples. This odd apple had an almost straight line dividing it into a speckled red section and a greenish yellow section. How could this happen?

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A. A clearly defined colour separation is not unusual in some apples. Gala is an example. Its natural colouring is red, in vertical streaks against a yellow-green background. Because absorption of sunlight favours optimal colouration, the parts of these apples most fully exposed to sunlight will be more red. The apple you saw was most likely partly shaded by foliage, causing the shaded part of the fruit to remain mainly yellow-green.

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Q. Some of my tomatoes developed tan coloured blotches at the far end. Beneath the blotched patches, the flesh began to rot. Is this a disease?

A. You have described blossom end rot of tomatoes, a common problem in home gardens this summer. It’s not a disease, but a physiological disorder caused by insufficient calcium in the fruit tissues.

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This does not necessarily mean the soil lacks adequate calcium. Blossom end rot is often the result of soil moisture levels insufficient to carry the needed calcium through to the far (blossom) end of a tomato, causing cells to collapse in that part of the tomato, with rotting to follow.

Hot sun and high temperatures from mid-May through August, together with almost no rain, made for a challenging growing season. Plants shrivelled in the heat. Seed germination was spotty. It was difficult to keep up with the watering.

It’s been a season filled with common reports of both sunscald and blossom end rot of tomatoes, and split carrots. Hot, direct sun combined with inadequate or/and uneven soil moisture levels play a part in all three. I’m even preparing to place shading materials over my tomatoes next year — a measure that would have been unthinkably unnecessary until this growing season.