Who recorded the first blue grass song?

Bill Monroe is known as the father of Bluegrass music, forming a band called the Blue Grass Boys in 1939, named after the state of Kentucky. Monroe's band developed a new sound said to be a combination of country, blues and gospel in the early 1940's. The first recordings and sales of the music was in 1946. The exact name of the first song has not been established. The new music genre has been called Bluegrass since the 1950's.