By Dan Shapley
Guster, the band that blends music with its earth-friendly message
, will headline the 14th Annual Earthfest, a free concert in Boston May 26. Also on the bill are KT Tunstall, Mat Kearney, John Butler Trio, Vega4 and Grace Potter and the Nocturnals. Organized by WBOS-FM, Whole Foods Market and the Massachusetts Department of Conservation and Recreation, EarthFest is billed as a carbon-neutral celebration for the Earth. Besides music, it showcases environmentally friendly products, groups, and activities.