BILLBOARD: Vampire Weekend will headline the third annual Roots Picnic, which will also feature a performance by the Philadelphia-based Roots plus two associated side projects from drummer Ahmir “Questlove” Thompson and rapper Tariq “Black Thought” Trotter. The event will be held June 5 at Philadelphia’s Festival Pier; tickets go on sale Friday (March 5) via LiveNation.com. Also on the bill are Clipse, Mayer Hawthorne, Nneka, the Very Best, Tuneyards, Das Racist, Bajah and the Dry Eye Crew and Pattern Is Movement. In addition, Questlove will play a set with fellow Philadelphia native DJ Jazzy Jeff, while Black Thought will perform […]