BUJUMBURA (Reuters) - Burundi's revenue from coffee exports rose 68 percent in October from a month earlier, boosted by a stronger world market, its industry regulator said on Friday. The small east Africa nation earned $8.6 million from the sale of 1,969,854 kg of coffee, up from $5.1 million collected in September from the export of 1,915,558 kg. "Buyers rushed to buy large quantities of coffee after the announcement in September that coffee prices will fall in the world's top producer, Brazil. Also because most buyers will soon leave on holiday season," regulator ARFIC said. Coffee, the land-locked country's top hard currency earner, generated $66.3 million in the April 2012-March 2013 crop year, versus $61.2 million in the 2011/12 season. ARFIC predicted earnings would decline sharply in 2013/14, with output seen falling by almost half to 13,000 tonnes from 24,000 tonnes in the 2012/13 season. Coffee bean growers in Burundi are increasingly switching to other cash crops such as bananas, complaining that coffee prices are volatile and that the fertiliser offered by government is of poor quality.