News of Bush's death was shared on his Facebook fan page on Friday.
He was born John Bush Shinn III in Houston's Kashmere Gardens neighborhood on Feb. 17, 1935. He had an uncle who hosted a radio program on Houston's KTHT-AM who encouraged Bush and his brother to perform on the air, according to a biography on lonestarmusic.com.
He moved to San Antonio as a teen, where he began singing before becoming a drummer for bands including the Mission City Playboys, the Texas Top Hands and the Texas Plainsmen.
He took on the stage name of Johnny Bush when an announcer introduced him by that name.
Bush went on to join country music star Ray Price and the Cherokee Cowboys thanks to his friend, Willie Nelson, in 1963. It was Nelson who helped finance Bush's first album in 1967, "The Sound of a Heartache."
He wrote "Whiskey River" in 1972 and it became a hit for both Nelson and Bush. Willie Nelson and Family continue to open live concerts with the tune.
Bush's characteristic vocal range led writers to refer to him as the "Country Caruso," but his gift was threatened when he lost half his vocal range in the early 1970s.
"The high notes, which in the past had come as easily and naturally as breathing, became raspy and strangled," Bush said later. "It was as if my throat was being choked off. What I felt was fear."
He was later diagnosed with spasmodic dysphonia, a rare condition that causes uncontrollable spasms in the vocal chords.
Therapy and Botox injections helped the star regain much of his range and he enjoyed a career comeback beginning in the mid-'80s.
Over the years, Bush recorded honky tonk staples like "Green Snakes on the Ceiling," "You Gave Me a Mountain," and "Undo the Right."
In his later years, Bush was asked whether he'd retire after a storied career that spanned decades.
"Retire from what? Breathing?" he asked rhetorically. "People only retire from jobs they hate. Performing is not a job-it's what I do and what I love."
Bush was inducted into the Texas Country Music Hall of Fame in 2003.
Johnny Bush was 85.
Listen: Johnny Bush -- Whiskey River
Listen: Johnny Bush -- Green Snakes On the Ceiling
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