GLENDALE, Colo. — Nearly a year after the nation's deadliest foodborne illness outbreak in more than two decades, Colorado cantaloupes are back in supermarkets.

Farmers near the town of Rocky Ford are going on the offensive to restore the fruit's reputation a year after melons from one of the area's farms caused a nationwide listeria outbreak.

They have banded together to trademark Rocky Ford melons and fund $800,000 worth of safety upgrades to prevent future outbreaks, but they must convince buyers that the melons are safe.

Last fall's listeria outbreak traced to Jensen Farms in eastern Colorado was blamed for the deaths of 30 people. It infected 146 people in 28 states with one of four strains of the disease, according to the Centers for Disease Control and Prevention.

Some farmers who had raised melons for decades decided to stop growing Rocky Fords this year. Only about a third of the land devoted to growing the cantaloupes last year is now growing this year's crop, according to the USDA's Farm Service Agency.

The Food and Drug Administration said last year that melons at Jensen Farms likely were contaminated in the operation's packing house.

The FDA concluded that dirty water on a floor, and old, hard-to-clean equipment probably were to blame.