George Kuo, one of the top elder statesmen of Hawaiian slack key masters, flouted the tradition of placing the headliner at the end of a show for many years at Milton Lau’s annual Slack Key Guitar Festivals. Kuo had two good reasons for taking the opening slot: It opened the show with a taste of traditional old-style slack key, and it gave him plenty of time to get to the Waikiki Beach Marriott Resort & Spa for his weekly kanikapila with Martin Pahinui and Aaron Mahi.

Kuo will open the Fifth Annual “Westside” Hawaiian Slack Key Guitar Festival on Sunday afternoon as usual, but for the first time in 18 years, he only has one reason for going first. Just over two weeks ago, his appearances at the Marriott came to an end, after 18 years.

Kuo revealed the split Saturday, just after a Hawaiian Music Hall of Fame awards luncheon at the Hyatt Regency Waikiki; Kuo is on the organization’s board of directors. It leaves a gap in the Hawaiian music schedule, with fans and visitors no longer able to see the slack-key master; Pahinui, one of the musician sons of Gabby Pahinui; and Mahi, former bandmaster of the Royal Hawaiian Band.

Fortunate for all that Sunday’s event puts Kuo in front of a crowd.

Kuo began playing slack key more than 40 years ago when he was in his teens, and continued his musical education at the University of Hawaii. As he was learning the craft, he met practitioners Keala Kwan, aka Leonard Kwan Jr., and Antone Gabriel, nephew of Albert Kewalo, who famously shared his knowledge of slack key with Raymond Kane in exchange for fish Kane caught.

“They got me hooked on the real Hawaiian slack key,” Kuo says.

In the years that followed, Kuo won a slack-key guitar contest at the Waikiki Shell and recorded his first album, “Nahenahe,” for Hula Records. He co-founded the Kipapa Rush Band and recorded with it, then joined the Sons of Hawaii at the invitation of Eddie Kamae.

George Winston selected him as one of the slack-key guitarists for the Hawaiian Slack Key Guitar Masters series. One of Kuo’s projects for Winston was a Hoku Award-winning duet album with steel guitarist Barney Isaacs; another was a solo album that earned him a second Hoku Award in 1997. He also recorded for Winston as a member of Hui Aloha with Martin Pahinui and Dennis and David Kamakahi, and as a trio with Martin Pahinui and Aaron Mahi.

“When we were growing up, there was no question about it: When you said ‘slack-key guitar,’ it had the really deep Hawaiian feeling,” Kuo said. “Today the artists have put a lot of pop, folk, jazz. So now it’s maybe 10 percent of a Hawaiian feeling and 90 percent of a fingerpicking style, of other styles of music.

“I still have a deep feeling for the old traditional style,” Kuo said. “That’s my favorite. The other pop music — it’s nice, it’s beautiful music, but that deep Hawaiian feeling is hard to come by.”

The tradition of Hawaiian slack key — known in Hawaiian as ki hoalu — began in the 1830s with Mexican “vaqueros” (cowboys) who came to Hawaii to teach Hawaiians how to herd cattle. For more than a century, slack key was almost entirely a grass-roots style of Hawaiian music that garnered little attention from the mainstream.

That began to change with the first modern recording of slack key, Gabby Pahinui’s 1946 recording of “Hi‘ilawe,” but even after that many slack key players kept their knowledge and their slack key tunings within their immediate families.

With the release of the first slack-key albums, by Pahinui, Leland “Atta” Isaacs and Leonard Kwan, followed by the cultural movement known as the Hawaiian Renaissance in the early 1970s, slack-key masters began sharing their knowledge with students from beyond their immediate ohana, and George Winston began making the recordings that would become the Hawaiian Slack Key Guitar Masters series.

Gabby Pahihui died in 1980. Lau presented the first slack key festival in 1981.

“Can you imagine that — 35 years ago?” Lau said last week. “We wanted to perpetuate and make people more aware of this art form, and what better way to do it than to do a free festival showcasing it? Any time we can collaborate with people in the community and other stakeholders that are into promoting Hawaii’s music, we want to do it.”

From a single annual festival in Waikiki, the series has grown to include Maui, Kauai and the Big Island — and spread on Oahu to include festivals in Kailua, the North Shore and Ewa. Lau has also presented slack key in Europe and Japan, and brought Japanese slack-key guitarists to play in Hawaii.

The guitarists playing this weekend represent three generations of musicians that range from Kuo down to 20-somethings Danny Carvalho and Aja Gample, and “special guest” Jonah Domingo, who is 14.

“Encouraging young people to take up the art form and do this is what we’re all about,” Lau said. “Without them we won’t be able to perpetuate the art form. It’s almost like if you don’t do it, you forget about it. The good part about it is that a lot of young people are getting involved. My son, Chris, who was 1 year old when we started this, has said he feels it’s his kuleana to continue the festivals when I retire.”

Kuo says he is happy to be first onstage playing slack key.

“Milton has been putting me in the very beginning, and I think that’s really wonderful because it sets the whole tone of what ka hoalu really is,” Kuo said. “When the people hear that in the beginning, they’re hearing the real slack key guitar as it started, and then later on they hear how it’s evolved.”