NESTL Rowntree said today it was confident that stringent precautions will prevent a disease called Witches Broom causing a world cocoa shortage and pushing up chocolate prices.

The disease, so called because it makes cocoa trees become swollen and branched, giving the appearance of a witches' broom, is said by scientists to be devastating crops on the Atlantic coast of Brazil.

Plants are also being hit by another disease called Frosty Pod, which involves cream- coloured spores which sit on the surface of the growing pod, leaving a frosty dusting.

Dr Gareth Griffith, of the University of Wales, Aberystwyth, writing in the latest issue of Biologist magazine, says the diseases have caused terrible destruction of crops in Brazil, putting an estimated 200,000 people out of work, and indirectly affecting another two million. The impact on world cocoa production is not massive, because South America produces only ten per cent of the total amount reaching world markets.

But if the disease were to reach the plantations of Africa, where more than half the world's cocoa is produced, a world cocoa shortage could be caused, pushing up chocolate prices.

York-based Nestl Rowntree is just one of many chocolate manufacturers who would be affected by such a shortage.

However, a spokeswoman said today it was happy that stringent precautions in place would ensure that the disease did not spread to Africa.

She said there was no reason why cocoa pods should be taken from one country to another, and there was a strict quarantine system in operation for plants.

Updated: 10:48 Monday, June 28, 2004