A 25 year old Cowiche man was killed in a tractor accident this morning in an orchard near the 8100 block of Bittner Road, about six miles east of Yakima. The Yakima County Sheriffs Office says the man was found on the ground near a running tractor with attached mower.  It appeared he was mowing in the orchard when he fell off the tractor. He was then run over by the tractor and the resulting injuries caused his accidental death.  He was treated by emergency personnel, but they were unable to revive him.  The Washington State Department of Labor and Industries is now investigating the accident.