Safety groups say about 300 people are killed on Wisconsin farms each year, accounting for more than 40 percent of farm deaths nationwide.

That has safety officials calling for measures to improve working conditions on farms, especially for children and teens who may not be aware of the dangers. The National Farm Medicine Center says more than 60 percent of farm deaths are caused by tractors and farm machinery.

Many of the deaths could be prevented by installing a safety rollover bar on tractors. Two-thirds of tractors in the state still don't have one. One reason is that some farmers may not be able to afford the newer tractors that have them.