Oct. 30 (Bloomberg) -- Brazilian coffee farmers are facing the worst flowering season in more than two decades as above- average rainfall threatens bean quality, said the nation’s biggest coffee grower’s cooperative.

In Guaxupe, Minas Gerais state, 262.8 millimeters (10.3 inches) of rain fell in October, a 17-year high, according to Cooxupe, as the cooperative is known. In September, the region got 215.8 millimeters, the most since records began in 1960.

“Quality of the beans will be hurt because flowering is a mess,” Joaquim Goulart de Andrade, a manager at the cooperative, said in a telephone interview today from Guaxupe. “Non-stop rainfall is preventing the crop from maturing evenly.”

Coffee trees in Brazil, the world’s largest producer, flower in September and October. Beans won’t develop properly until the flowers fall from the trees during a period of drier weather, Andrade said. Flowering this year is the worst since 1983, he said.

Output and Exports

Cooxupe’s 11,500 growers, which account for 13 percent of Brazil’s arabica output, will harvest 4 percent less next year than in 2008, the last time coffee trees in Brazil were at the higher-yielding end of a two-year cycle, the cooperative said Sept. 23.

World coffee exports were 6.92 million bags in September, down from 8.09 million bags a year earlier, the International Coffee Organization said in a report on its Web site today. Total coffee exports from Brazil fell 12 percent in September from a year ago, the coffee exporters’ council, known as CeCafe, said Oct. 6.

Arabica-coffee futures for December delivery fell 1.25 cents, or 0.9 percent, to $1.354 a pound on ICE Futures U.S. in New York. Prices fell 1.2 percent this week, after dropping 4 percent last week.

Before today, coffee jumped 22 percent this year amid tight supplies from Central America and Colombia, the world’s largest producer after Brazil and Vietnam.

To contact the reporters responsible for this story: Lucia Kassai at lkassai@bloomberg.netHelder Marinho in Rio de Janeiro hmarinho@bloomberg.net.

Last Updated: October 30, 2009 15:42 EDT