The Roots Picnic — the once Philly-centric Black music festival, which over 16 years has become a perennial soft launch for the summer concert season here in the Northeast — can now safely be thought of as a national event. Atlanta’s Gunna graces the same stage as North Carolina’s Fantasia Barrino. St. Louis natives Smino and current sex-rap queen Sexyy Red follow each other as gospel is performed on a stage within earshot. Redman and Method Man, Ghostface and Nas, all New Yorkers and occasional collaborators, hit the stage for separate sets. The headliner of the weekend was a kind of New Orleans review: Lil Wayne on stage with his Nola compatriot, the horn player Trombone Shorty.