“…. commissioner Landis is touring the Florida orange and grapefruit league.” John B. Foster, Harrisburg Telegraph, March 15. 1923, p25 (Also appeared in other papers)
Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1ST USE. 1924. “[Donie Bush retained] the leadership that he enjoys at the head of the grapefruit league” (N.W. Baxter, The Washington Post, March 26).