An Ontario-wide construction strike by 25,000 members of the Laborers International Union of North America that began June 4 has prompted provincial Labour Minister Steve Peters on June 11 to appoint construction mediator Robert Herman to head a commission to seek a resolution.  The dispute is between the union and the Employer Bargaining Agency for the Labourers. The management group represents five construction employer associations. The strike is affecting construction at hundreds of industrial, commercial and institutional sites across the province, including a Toyota Corp. manufacturing plant in Woodstock, near Toronto, says Ministry of Labour spokeswoman Belinda Sutton. It began after two months of failed negotiations over a new three- year contract. Officials of the laborers’ union and Toyota could not be reached for comment. In a statement, the union blames the lack of a monetary offer  on employer squabbling.