Legendary country singer Merle Haggard wasn’t shy about his thoughts on modern country music: He hated it.

The majority of contemporary artists “sound like a bunch of [crap],” he said in an interview last fall. “They’re talking about screwing on a pickup tailgate and things of that nature,” Haggard added. “I don’t find no substance. I don’t find anything you can whistle and nobody even attempts to write a melody. It’s more of that kids stuff.”

It’s no surprise that Haggard, who died at 79 on Wednesday, wasn’t a fan of “bro country” that does often involve male singers entertaining pretty girls in tight jeans on truck tailgates. Imagine his reaction when he was name-checked in Florida Georgia Line’s 2014 single “Sun Daze,” which talks about rocking “a little bit of hip-hop and Haggard and Jagger” in between playing flip-cup and getting laid.

But Florida Georgia Line aren’t the only modern singers who boast about their love of Haggard’s music. “Love” might be an understatement: It’s more like awed reverence. Sometimes, Haggard enjoyed the admiration. He sang a verse on Eric Church’s 2006 fan-favorite “Pledge Allegiance to the Hag,” which describes a rowdy Southern bar that comes to a respectful halt when a Merle song plays: “You can hear a pin drop as ol’ Jack drops in a quarter and plays Merle on that jukebox/And we stop and tip our hats, and raise our glasses…. I pledge allegiance to the Hag.”

Respect for the Hag as an icon, both for his musical status and his personal views, is a common theme: Haggard lent his vocals to Blaine Larsen’s 2005 “If Merle Would Sing My Song,” about how a struggling Nashville singer’s ultimate career goal would be for the country legend to cut one of his songs. The same year, Haggard was featured on Gretchen Wilson’s “Politically Uncorrect,” a defense of working-class views. (“I’m for the Bible and I’m for the flag/And I’m for the working man, me and ol’ Hag.”) “I guess my opinion is all out of style,” Haggard vents on the track.

His blunt, outspoken nature clearly had an effect on many country singers, though he felt honesty was increasingly rare in country music: “Radio doesn’t want substance,” Haggard told The Post in 2007. “If a song actually had an opinion, that’s the first thing they’d throw in the trash.”

Indeed, George Strait and Alan Jackson say as much in their 2000 hit “Murder on Music Row,” angry that rock and pop had seeped into Nashville: “The steel guitars no longer cry and you can’t hear fiddles play, with drums and rock ‘n’ roll guitars mixed right up in your face/Why the Hag wouldn’t have a chance on today’s radio since they committed murder down on music row.”

Lyrics that name-dropped Haggard became a euphemism for authenticity. Up-and-coming singer Mo Pitney hoped to earn respect with “I Met Merle Haggard Today.” Jamey Johnson’s 2006 “Ray Ray’s Juke Joint” bemoans a city slicker who bought a honky tonk and fired the band that used to play Haggard’s “Okie from Muskogee” and replaced it with a karaoke singer. So Johnson invites real country fans to a real Southern watering hole: “Three plays for a quarter on the jukebox in the corner, and it’s full of Hank, Haggard and Cash,” he sings. The Dixie Chicks feel the same way in their 2002 cover “Long Time Gone,” which vents about new singers: “Now they sound tired but they don’t sound Haggard,” they sigh.

Photos: The life and career of country music legend Merle Haggard

Merle Haggard performs at the Aladdin Theater for the Performing Arts in Las Vegas while touring with Willie Nelson and Ray Price. Haggard began playing guitar at age 12. (Ap Photo/LAURA RAUCH)

Name-checking Haggard’s songs is also a popular move, from David Nail’s 2011 “Sound of a Million Dreams” (“When I hear ‘Mama Tried’ I still break down and cry”) to LeAnn Rimes’s 2013 “I Do Now” (“Thank God for Merle Haggard, he’s right, the bottle let me down.”)

Through the years, whether you were a Haggard fan became a barometer of your music credibility. For instance, some ’90s country singers used Haggard to judge if a woman measured up to their standards: “Acts like Madonna but she listens to Merle,” brags Brooks & Dunn in 1993’s “Little Country Girl.” Collin Raye feels even stronger on “My Kind of Girl” in 1994: “I said, ‘How bout some music? And you said, ‘You got any Merle?'” he reminisces to his lover. “That’s when I knew you were my kind of girl.”