‘I fully understand all the implications of everything I’ve suggested,’ said Professor Protter. ‘But I must repeat that so far it’s only guesswork – and by my usual standards, pretty wild guesswork. We may still find that this gelatinous material is completely unconnected with the virus.’

‘What about the samples from Iowa? The corn, and the soybeans? And all that stuff they were supposed to be sending you from California?’

Professor Protter paused for a moment, while he consulted his notes. ‘We haven’t run tests on everything yet. We just haven’t had the time. But we’ve examined some grapes from Bakersfield, California, and there isn’t any question at all that they’ve been attacked by a similar species of virus.’

Peter was silent. It seemed as if Dr Benson’s first guess at the cause of the blight had been correct. It was a virus – and even more frighteningly, it had been spread deliberately.

Professor Protter said, ‘It wouldn’t have needed much spraying to start the virus off, you know. Just a couple of acres out of each farm. Once the virus gets going, it’s almost unstoppable. We reckon it can ruin an acre of prime wheat in two to three hours.’

‘All right,’ said Peter, distractedly. ‘Thanks for everything you’ve done. You’ll complete those tests on the rest of that California crop, won’t you? And you’ll remember that you’re bound to complete secrecy by federal law?’

‘I won’t forget,’ said Professor Protter, sourly. ‘Although how you’re going to keep the lid on a nationwide blight for very much longer, I don’t have any idea. I’ve already had die newspapers and the television stations calling me here.’

‘We don’t want panic,’ Peter told him. ‘If people start to panic, they’re going to rush around to their local supermarkets and empty the shelves in an hour. Once the president knows what’s going on, he’ll probably want to issue rationing instructions.’

There was a silence, and then Professor Protter said, ‘The president doesn’t know?’

‘Of course the president knows. He’s aware of the blight, and he’s aware that it’s spreading, but he gets all his information from the Depar’I’ment of Agriculture, and so far we’ve tried to keep the blight in perspective.’

‘In perspective?’ asked Professor Protter. ‘Don’t you know what’s going on out there? We may have lost fifteen per cent of our annual crops already!’

‘Professor Protter,’ said Peter, tersely, ‘you’re paid to find out what causes crop diseases, and to suggest antidotes – not to indulge yourself in wild political speculation.’

‘Sometimes a job goes beyond what you’re paid to do,’ retorted Professor Protter.