Global grain prices have risen since the start of the flooding in Queensland.
The BBC reports US high-protein wheat futures in Kansas City and Minneapolis hit two-year closing highs on Tuesday.
Australia is the fourth-largest exporter of wheat in the world. However, Queensland accounts for only 5% of Australia's wheat exports.
Analysts have also warned that the flooding in Queensland will put up the price of sugar cane, its other main crop, plus fruit, vegetables and dairy products.
The inundated area is equivalent in size to France and Germany.