NEW ORLEANS (AP) - Researchers from Mississippi and Florida say a single female fungus-farming beetle could have been the source of a disease that has killed an estimated 300 million redbay trees and threatens Florida's avocado groves.

The beetle and her fungus arrived in Georgia in 2002, and their clones have spread west into Texas and north to North Carolina.

Mississippi State University researcher John Riggins says they could spread nearly to Canada on sassafras, the source of the powder used to thicken filé (FEE-lay) gumbo.

Researchers at the University of Florida say bay leaves used for cooking could also face problems if this species gets into the Mediterranean areas where bay laurels are cultivated and grow wild.

The U.S. infections all apparently come from one itty bitty beetle, or one beetle and her immediate offspring.