It was a routine burn of a sugar cane field before harvest.
Mr. Rewrite thought of those halcyon days, of reading on the beach, of drinking in gorgeous sunsets (along with Budweiser over ice -- the way the locals liked it), of waffle hot dogs (seriously -- hit that link), when an article referred mistakenly to a sugarcane farmer.
Even as an adjective, you're going to go with two words. You wouldn't refer to a greenbean farmer, would you? Mr. Rewrite uses Webster's New World College Dictionary and common sense for guidance here.
By the way, did you know the AP Stylebook, which doesn't address sugar cane, has a sugar entry listing different types and noting that it's OK to write sugar when recipes refer to granulated sugar? That's helpful. There's also an entry codifying AP's preference for superfine sugar, whatever that is.