A 13-year-old Greenville boy is killed when a tractor pulling an end loader from the mud flipped and killed him instantly.

Farm safety experts say the death of Duane Ashauer and others could have been prevented if old tractors were retrofitted with roll bars.

Tractors made since 1985 have rollover protector bars but older tractors don’t and are still being used.

The center's research engineer Mark Purschwitz says it's going to take some financial incentives to get the necessary retrofitting.

The National Farm Medicine Center at Marshfield estimates that there are about 150 tractor rollover fatalities a year.