July 25 (Bloomberg) -- Nigeria's cocoa crop, the fifth biggest in the world, may suffer more than normal from black-pod disease as heavy rain lashes the country's southern growing belt, industry officials said.

Most cases of the fungal disease are in the southeast region, where the tropical rains are heavier than in the southwest, Robo Adhuze, a spokesman for the Cocoa Association of Nigeria, which groups farmers, processors and traders, said by phone from the cocoa-trading town of Akure.

Wet weather creates mold that spawns the infection and turns cocoa beans into dust. In the southwest Ondo state, which accounts for as much as 40 percent of Nigeria's cocoa, some cases have also been reported, said Bamidele Olamigoke, a farmer and member of the Ondo Cocoa Farmers' Congress.

With the wet season at its peak and rain falling incessantly in most of the southern cocoa-growing region, industry officials are concerned the disease may spread.

``The rains are very heavy now so that we can't rule out black pod,'' said Henry Adesioye, of Nigeria-based Stanmark Cocoa Processing Co., a unit of Cadbury Nigeria Plc.

The cocoa association's Adhuze said reports so far of the disease ``are nothing more than usual.''

The west African country produced 160,000 metric tons of cocoa in the 2006-07 season, according to the International Cocoa Organization's Web site. The country may harvest 210,000 tons of beans in the current season, the organization forecast in April.

Nigeria is the world's fifth-biggest producer of cocoa after Ivory Coast, Ghana, Indonesia and Cameroon.

Cocoa for September delivery on ICE Futures U.S. rose as much as $79, or 2.9 percent, to $2,823 a ton, and traded at $2,805 a ton as of 1:07 p.m. New York time.

Cocoa traded on Liffe in London has climbed 44 percent this year, more than double the increase in the UBS Bloomberg CMCI Index.

To contact the reporter on this story: Dulue Mbachu in Lagos via Johannesburg at pmrichardson@bloomberg.net.

Last Updated: July 25, 2008 13:15 EDT