Forty six years ago, a group of amateur conservationists and birdwatchers in Wisconsin took on the nation’s chemical industry and won. The fight to ban the pesticide dichlorodiphenyltrichloroethane, better known as DDT, — a fight many have cited as the genesis of the modern environmental movement — has its roots right here in Wisconsin. Bill Berry has made a career of documenting Wisconsin environmentalists, and he has a new book “Banning DDT: How Citizen Activists in Wisconsin Led the Way.”