January 2/London/Mail on Sunday -- The price of orange juice is set to rise by up to a third after cold weather and disease hit citrus groves in Florida.

The American state is one of the world's main producers, and the problems it has experienced have already led to the price of concentrated juice doubling in a year.

Supermarket prices have been reasonably stable so far, but experts say this is only because stores fix prices with suppliers months in advance.

Clive Webster, executive secretary of the British Fruit Juice Association, said he expects prices to rise by between 10-30% when contracts are renegotiated, depending on foreign currency fluctuations.

He said, "There's bound to be an impact when the raw price goes up. Supermarkets will be very reluctant to put prices up but they will have little choice when their contracts end."

A survey of U.K. supermarkets over the past year has shown prices are yet to rise significantly. A one-litre carton of smooth Tropicana rose from £1.81 to £1.90 at Waitrose and from £1.57 to £1.66 at Sainsbury's.

However, the price of concentrated orange juice has already soared on world markets, from 43p per pound a year ago to more than 80p per pound last week.

The U.S. government expects this season's yield of Florida oranges to be down 17 % on last year, at 135 million boxes, because cold weather and "spotty" rainfall have meant smaller oranges and fewer fruit per tree.

The state's orange groves have also been ravaged by the deadly, incurable "greening disease, " which originated in Asia and forces farmers to uproot trees.

Millions of dollars have been spent on aerial pesticide spraying in an attempt to reduce the population of the insect that spreads the disease -- the citrus psyllid.

However, this is little comfort for people who prefer an alternative drink with their breakfast. Other breakfast staples such as tea, coffee, sugar and cocoa are also at their highest prices for decades, again because of the fluctuating weather.  

From the January 4, 2010, Prepared Foods E-dition