(Keizer, OR)  --  An employee with a tree-service company is in custody, after being accused of trying to throw his co-worker into a wood-chipper.  Authorities say 26-year-old Scott Edward Iverson of Stayton tried at least twice to push the 22-year-old victim into the machine Thursday.  Another employee then intervened and pulled Iverson off the other man.  Police say they arrested Iverson Friday on assault charges.