The 2008/09 Californian navel orange crop will be down 34 per cent from last season, according to the US Department of Agriculture (USDA).

Production is projected at only 32m field boxes (1.09m tonnes), compared to 48.5m boxes last year (1.65m tonnes).

A USDA survey carried out in California’s Central Valley between 21 July and 27 August found average fruit set per tree was a record low, 48 per cent lower than last season and 23 per cent lower than the previous record.

Industry sources say last year's navel crop was the largest in Californian history, and the trees will naturally 'rest' after such a big season, but bad weather also pushed the crop down.

A heat wave and high winds in May caused a large fruit drop. The average fruit size is lower than normal, but the quality of the fruit is expected to be good nonetheless.