David Randall: If you want booming growth, you can't afford to be thin-skinned

It falls to the journalist to investigate many things: the inner whirrings of the world economy, the ebb and flow of political fortunes, and even the whys and wherefores of the Government's health policy. By the time you get to this end of the paper, however, these matters have been dealt with, and so it falls to me to tackle the issue that other writers have so adroitly avoided: The Great Exploding Watermelon Mystery.

It was a story that made headlines all round the world, although they were, admittedly, very small ones. The bare bones are as follows. China's economy is booming, and the price of almost everything is going through those curiously shaped roofs. The result? A sudden burst of enthusiasm for growing these large, succulent and profitable fruits, and so, entering the fields in the fertile east of the country, was a group of first-time growers, of whom a man called Liu Mingsuo was typical.

He sowed, tended and, despite a long, dry period, was preparing to reap. Time, he thought, for one final bit of assistance for his swelling fruit: the application of a growth hormone called forchlorfenuron. On 6 May, he applied the dose (it doesn't take much – eight to ten grams for a whole acre of grapes, apparently) and sat back to await the results. On 7 May, he went out to inspect his crop and found, to his surprise, that 80 of the watermelons had exploded. By the afternoon, 20 more had blown themselves up, and, by 9 May, two-thirds of his three hectares of melons had spontaneously erupted.

And he was not alone. About 20 other growers had the same experience (all told, 120 acres of melons had been affected), but only a few had sprayed forchlorfenuron. Yet the combination of the presence of this growth hormone and the dramatic explosions across eastern China's melon fields (one farmer likened the effect to that of landmines going off) was enough, in several excitable minds, to indict the chemical, especially in a country where there has been no shortage of unpleasant extra ingredients being added to foodstuffs: melamine to milk, steroids to pigs, borax to pork (and then selling it as beef), arsenic to soy sauce, bleach to popcorn, sugared water to wine, and water to stale buns before recycling them as fresh ones.

But unlike these substances, forchlorfenuron is a plant hormone, and harmless to humans, according to experts such as Professor Wang Liangju, of the Nanjing Agricultural University's College of Horticulture. He is the man who investigated the great watermelon mystery, and he said there were three causes: forchlorfenuron being applied to ripe, rather than young, fruit; the heavy rains of 7 May, and the fact that the melons being grown were a variety whose skin was notoriously thin. The growth hormone is also approved for use in the US and Australia, and widely sprayed on commercially grown grapes and kiwi fruit.

Where it doesn't seem to be applied – and I throw this idea out to any ambitious horticulturalist – is to the crops that every autumn set new records for size and weight at fruit and vegetable shows. Last year, for instance, a Shropshire man grew a 70lb cabbage, big enough for 300 servings of cabbage soup should you want such a thing (but still 54lbs short of the record); and a potato shown at a West Country show set a new best at 8lb 4oz. Britain also holds the world record for the longest beetroot (21ft), longest carrot (19ft 2in), and the heaviest parsnip (13lbs), marrow (113lbs), and gooseberry (2.19oz). And if that does not bring a patriotic tear to your eye, we even used to hold the world record for the heaviest lemon, and last year a Cambridge mother grew a 5ft 6in courgette. Just think what we could achieve with a bit of forchlorfenuron.