Brazil's key Center-South sugarcane region registered a decline in ethanol output in the second half of September amid heavy rains that shut down harvest operations for as long as a week at some sugar mills, Unica said Thursday, Platts Commodity News reports. Sugar mills produced 1.567 billion liters of the biofuel in the September 16-30 period, down 2.2% from the 1.602 billion liters produced in the same period of last year, the cane-growers association said.