LONDONDERRY, N.H., Oct. 24, 2011 /PRNewswire/ -- Stonyfield, the world's leading organic yogurt maker, has entered into a two-year sponsorship agreement with plans to support USTA League players through online health and fitness content; sampling for members at USTA League National Championships; as well as ongoing promotions and programs exclusive to USTA members. Stonyfield will be the Official Yogurt of USTA League, the country's largest recreational tennis league with more than 335,000 players nationwide.