Current Mark Ronson collaborator Wale is the latest special guest scheduled to perform with The Roots at the Green Apple Festival’s festivities at Washington, DC’s National Mall. As previously reported, a number of special guests will join The Roots onstage throughout their headlining performance, including Doug E. Fresh, Ne-Yo, Talib Kweli, will.i.am and Chrisette Michele. The Roots have a long history with Green Apple founder Peter Shapiro, who hosted the hip-hop crew’s Black Lily series at his esteemed club, Wetlands. Other acts scheduled to appear at the National Mall this Sunday as part of Green Apple include: Gov't Mule, Umphrey's McGee, Thievery Corporation, Toots & The Maytal, Warren Haynes, Mambo Sauce and CityDance Ensemble, among others. In addition, American Idol champ Jordin Sparks will kick off the day’s festivities with her take on the National Anthem, while O.A.R. will offer a special acoustic set. For more on Green Apple please click here.