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Questions and answers should be concise. We reserve the right to edit items for clarity and style. Include a daytime telephone number and email address if you have one. Restrict questions to scientific enquiries about everyday phenomena. The writers of published answers will receive a cheque for £25 (or US$ equivalent). Reed Business Information Ltd reserves all rights to reuse question and answer material submitted by readers in any medium or format. New Scientist retains total editorial control over the content of The Last Word. Send questions and answers to The Last Word, New Scientist, Lacon House, 84 Theobald’s Road, London WC1X 8NS, UK, by email to [email protected] or visit www.last-word.com (please include a postal address in order to receive payment for answers). For a list of all unanswered questions send an SAE to LWQlist at the above address. THE LAST WORD Do the splits Sometimes I buy raw carrots that have split lengthways. They have a deep crack along one side, but still seem edible. What causes this? Does the same thing happen in similarly shaped vegetables such as parsnips? n Carrots contain a lot of moisture, and if they crack after they have been harvested then it is likely that they have been allowed to dry out. Prior to sale, they should be stored under cool, shady conditions, rather than being exposed to hot and dry conditions, such as those found on a market stall in summer. If the carrots cracked while still in the ground, then this could have been caused by excessive use of nitrogen fertiliser, particularly during the early growth period. More likely, however, is that the carrots were grown with a variable water supply. Carrots require a plentiful and evenly distributed supply of moisture throughout the growing season. When the soil is not damp enough, the main root develops many small feeder roots, so that it can soak up any available moisture more efficiently. However, prolonged drought conditions during the later stages of growth, followed by a sudden period of heavy rainfall, will cause the carrot to absorb too much water too quickly and splitting will result. Parsnips grow much more slowly than carrots, making them much more resistant to cracking, although the problem is not unknown after very adverse growing conditions. John Crofts Former horticultural consultant Nottingham, UK Paired pear I was harvesting pears and found this little beauty (pictured, right). I have a red pear tree, and 10 metres away a green pear tree. I’ve had some green/yellow stripes on the red pears for the past few years, but this takes the cake. What’s going on? n The right half of the pear on the photograph looks mouldy and is likely to be infested by a fungus. It is coloured bluish white, has a dull texture and is in contrast to the sound, glossy red surface on the left. But the sharp and straight delineation between the two halves is most remarkable. I think that this pear is a chimera, which is sometimes found in fruit varieties that are grafted onto a wild stock, as your questioner has already observed in the past, having seen “some green/yellow stripes on the red pears”. The graft in this case is obviously more resistant to the fungus than the original stock part. Pieter van Doesurg Retired biologist Rijnsburg, the Netherlands This week’s questions CRUNCH TIME Why does freshly fallen snow squeak and creak when you step on it? Pauline Lacey Lincoln, UK BAG BREAKDOWN I found this plastic shopping bag (see photo, left), which was full of other plastic bags, stored in the bottom of a wardrobe. Though the bag is labelled as “100% degradable”, I wonder why it should start to degrade in the absence of light or moisture, and especially why the red parts should degrade first. Warner Haldane Whakatane, New Zealand Last words past and present, plus questions, at last-word.com The new book out now: packed full of wit, knowledge and extraordinary discovery Available from booksellers and at newscientist.com/dolphins Will we ever speak dolphin?
