This year's unprecedented crop will cause world cotton prices to fall to 47 cents per pound, down from 68.3 cents in 2003/04, the group said in its monthly outlook report.
"Declining cotton prices in 2004/05 are expected to curtail plantings in 2005/06," the group said.
World plantings was forecast to decline to about 33 million hectares (81.5 million acres) next year, down 2 million hectares (4.9 million acres).
Although plantings will decline, ICAC forecast world cotton production in 2005/06 to be the second largest on record at 22.9 million tonnes.