Arabbers, or singing fruit vendors, Tyrone Diggs-Bey and LaMont Williams sing "Watermelon" at the Smithsonian Folklife Festival in D.C. (Linda Davidson/The Washington Post)

Even amid the cacophony of Smithsonian Folklife Festival sounds — Mongolian throat singing, Kenyan storytelling workshops, a lesson in flower drum lantern dancing — Tyrone Diggs-Bey’s baritone stands out.

“Watermelon, watermelon. I got grapes, I got pineapples too, I got something just for you. Watermelon, watermelon time. I’m not talking about melons light. I’m talking about watermelons — they’re ripe.”

The dozen people lined up in front of a smoothie booth next door all applaud, and one onlooker walks over to buy grapes from Diggs-Bey’s father, Melvin Diggs. An expert showman, Diggs-Bey tips his hat to the audience and grins.

Although this year’s festival celebrates the folk cultures of Kenya and China, Diggs-Bey and his family occupy two small corners set aside for preserving a tradition that originates much closer to home. They are, as they proudly call themselves, “arabbers” peddlers who hawk their produce from horse-drawn carts with lyrical and sometimes comical auction calls, or “hollers.”

Arabber Preservation Society President Daniel Van Allen knows that for anyone not from Baltimore, the term may prompt some raised eyebrows. Though the word’s orgins are murky — it has been connected to the Dickensian term “street Arab,” among other things — it’s most likely that “arabber” comes from the Greek word for a fine horse.

“There’s a lot of Greeks here in Baltimore, so it might have been Greek,” he says. “But in all the speculation, there’s no documentation anybody’s found that it’s offensive.”

In Baltimore, the word was once ubiquitous — like the arabbers themselves. Mostly African American, the vendors operated brightly painted wagons led by teams of horses decked out in bells.

“It was part of the music of the city,” Van Allen says. “The rattling wagon, the jingle bells, guys hollering.”

But the musical salesman population declined dramatically in the decades after World War II, when large grocery stores replaced street markets and city governments stopped including stables in their urban planning. Now the traditional horse-cart vendors can be found only in Baltimore, where three small stables help to maintain a community of about six full-time merchants.

The Diggses are a bedrock of the Baltimore community and a Folklife Festival institution: They’ve been peddling fruit here since 1972. And although their wares aren’t anything that can’t be bought at the supermarket — pineapple, grapes and watermelon in cardboard boxes labeled “Dole” — the family has an idiosyncratic charm you won’t find in the fruit aisle.

At the opposite end of the festival from Tyrone’s ode to watermelon, Sonny Diggs, his uncle, oversees his daughters as they set up their booths. (They no longer bring their horses and wagons because the festival gets so crowded.)

The first thing Sonny wants visitors to understand about his profession is how to pronounce it:

“It’s ey-rabber,” he says, elongating the A and stressing the double B. “Not ah-rapper, like I’m one of those singer people.”

Sonny has been selling things from wagons for almost 70 years: As an enterprising 6-year old, he peddled penny candy from a cart he’d built out of a cigar box, with two coat hangers as axles and spools of thread for the wheels. When he was 12, an established salesman took Sonny under his wing — the two would peddle fruit together in the mornings, and then the younger boy would drive the wagon on his own, collecting debts owed to his boss.

“He trusted me,” Sonny explains. “Just like the Smithsonian trusts me. I’ve been coming here 42 years. You think that would happen if I was a bad guy?”

According to Sonny, trustworthiness and courtesy are the most important qualities of a good merchant — even more essential than singing.

“People would buy stuff way back then from people that they liked,” he says. “You had people who enjoyed an arabber like they were friends. . . . So you had to have good manners.”

To those requirements, Tyrone would add showmanship. A good salesman must decorate his wagon and take good care of his horses. And when he sets out to sell his wares he doesn’t walk — “he struts.”

Tyrone channels that sentiment when he sings his auction calls, which are entirely improvised.

“I just feel like, ‘okay, it’s showtime,’ ” he says. “And then it’s really being in the zone, and you feel it, and its just like [the words] come out.”

Melvin and Sonny are among the last of a generation for whom it was possible to make a living from peddling produce. Even so, Sonny — who is now retired — had to hold down jobs ranging from scrap collector to Social Security Administration aide to supplement his income. For Tyrone, singing while he sells is a twice-a-month hobby, while Sonny’s daughters sell fruit only when they come to the festival each year.

African American food historian Jessica Harris fears that the practice is “moving toward museumhood.”

“It’s wonderful that’s it’s maintained itself as vitally as it has,” she says of the Baltimore community. “But it’s sort of preserved in amber.”

For his part, Sonny doesn’t worry too much about the future. It’s enough to see “the heart” of the tradition in his children, even though they don’t work at it full time.

“They’ve got the manners,” he says, nodding toward his eldest daughter, Pauletta Diggs, as she speaks with a customer.

He smiles, satisfied at the interaction.

“You see, it’s so good,” he says. “It’s in their blood.”